Timeline of Photography

As you may have noticed, I’ve added a timeline page to ATG, which is turning out to be an exciting project.

I’ve wanted to add historical information for some time now, but writing an account of how photography came to be as we know it today proved a daunting task. I decided instead to put it in the form of a timeline, which works quite well on an endless scrolling web page. The only difference is, it goes from top to bottom instead of left to right.

Today, I decided to add blank lines to represent the years between events. It seems to provide a more accurate graphic portrayal of the passage of time.

It’s a good start, but by no means even near complete. I’ll be adding new facts as I come across them, so it will get more and more dense as time progresses. Perhaps at the end of it all, I’ll use it to write that historical account.

Until then…

The Sensor

The Sensor is the light-sensitive electronic component of a digital camera which captures the image to be stored in memory. The information gathered by the sensor is passed on to the imaging engine and subsequently stored in binary format on a flash memory card.

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The Film

Film is the light-sensitve media on which captured images are stored. Image information is stored as “latent” images which must be processed in order to be made visible.

Film comes in many different formats, that is sizes and aspect ratios. The most common format of film is 135 or simply 35mm, whose dimensions are 36mm x 24mm. It is said to have a 3:2 aspect ratio; that is its height is two-thirds of its width (or, its width is three-halfs of its height). The second most common type of film is 120 which can have several formats, the most common of which is 6cm x 6cm, a square format with an aspect ratio of 1:1. Square formats have the advantage of not requiring any rotation of the camera. Other 120 formats are 7cm x 6cm, and 6cm x 4.5cm and 9cm x 6 cm. There are many other film formats as well.

Film formats are divided into three classes based of film size; Small format (135), Medium (120, 220), and large (4x5, 5x7, 8x10). There can be many “formats” in terms of aspect ratio within a give film size.

Film is supplied in light-tight cartridges (110, APS and 135), rolls (120), or sheets (4x5, 5x7, 8x10).

Film comes in many different emulsions with different color, saturation, contrast and grain characteristics. The most common emulsion produces a negative image which becomes a master for producing prints. The next most common emulsion produces a positive image which can be viewed directly or projected, as well as being printed through a more complicated process. Most emulsions are balanced for daylight, although some are available for tungsten.

Film comes in many different sensitivities or “speeds” ranging from ISO 3200 (fast, coarse grain) to ISO 25 (slow, fine grain), the most common being ISO 200. The acronym ISO is used to denote film speed, but it is actually the logotype designation for the International Organization for Standardization. Prior to ISO, ASA/DIN was used, the acronym for American Standards Association and German Institute for Standardization (Deutsches Institut für Normung). Most cameras have an ISO setting to tell the metering system which speed of film you’re using. You can set it to match the speed of the film, or set it one to two stops higher to “push” the film, or one to two stops lower to “pull” the film. If you do this, you must process the film at the ISO the camera was set to in order to compensate. Some films respond to this technique better than others.

Which film speed you use depends on the lens speed, aperture range, shutter speed range, and lighting conditions. Fast speed film is used in conjunction with faster shutter speeds to capture action, or subjects in low light. Slow film is used in conjunction with slower shutter speed to increase resolution in still subjects, or in bright light.

Formats at a glance:
(Dimensions are width x height in the natural orientation of the camera)

110 
110, 17mm x 13mm, 4:3 aspect ratio, landscape orientation

APS

APS-C (Classic), 25.1mm x 16.7mm, 3:2 aspect ratio, landscape orientation

APS-H (High Definition), 30.2mm x 16.7mm, 16:9 aspect ratio, landscape orientation

APS-P (Panoramic) 30.2mm x 9.5mm, 3:1 aspect ratio, landscape orientation

135

full-frame, 36mm x 24mm, 3:2 aspect ratio, landscape orientation
half-frame, 18mm x 24mm, 3:4 aspect ratio, portrait orientation
square, 24mm x 24mm, 1:1 aspect ratio, universal orientation
sprocket hole, dimensions, aspect ratio and orientation governed by camera’s mask.

120, 220
6x6 (square, 2-1/4"), 6cm x 6cm, 1:1 aspect ratio, universal orientation
6x7, 7cm x 6 cm, 7:6 aspect ratio, landscape orientation
6x4.5, 4.5cm x 6cm, 6:4.5 aspect ratio, portrait orientation
6x9, 9cm x 6cm, 3:2 aspect ration, landscape orientation

Sheet Film
4x5, 12.7cm x 10.2cm, 5:4 aspect ratio, portrait or landscape orientation
5x7, 17.8cm x 12.7cm, 7:5 aspect ratio, portrait or landscape orientation
8x10, 25.4cm x 20.3cm, 5:4 aspect ratio, portrait or landscape orientation

The Shutter

The shutter of a camera is a device which controls the period of time light enters the camera. It blocks the light and prevents exposure until the picture is to be taken. On demand, it slides out of the way for a period of time, and then slides back to stop the exposure.

Shutter speeds are designated in fractions of a second, and can be set with a variety of different controls. On most film cameras, a dial is located on the top of the camera which sets the the shutter speed mechanically. On digital cameras the shutter may be controlled electronically through a thumbwheel or command dial, or through a menu.

Every camera has a range of shutters speeds from about 2 seconds up to 1/4000 of a second, depending on the performance characteristics of the shutter. Which of the available shutter speeds you can use depends on several other factors; the range of available apertures, the ISO setting of the camera, and the available light.

Which shutter speed you should use depends on the effect you are trying to achieve, which will vary depending on the movement of the camera, the subject or both.

Motion blur is an effective means of expressing movement in a photo. It occurs when the movement of the camera or subject is recorded over time by using a slow shutter speed. You can pan on a moving subject, keeping it relatively sharp while blurring the background for separation, or you can hold the camera stationary and let the subject’s movement tell the story. You can photograph a moving stream or a body of water and soften it with a longer than necessary exposure.

The ability to freeze motion can be a powerful way of capturing the moment. It also assures the sharpest possible image, which relies on the ability of the shutter to eliminate any movement of the camera.

• 30 seconds — The lower limit of typical Digital SLRs. Usable for digital pinhole or infrared work.

• 4-15 seconds — The lower limit of typical compact or bridge digital cameras. Usable for digital pinhole or infrared work.

• 1-2 seconds — The lower limit of most mechanical shutter 35mm SLRs. Useable for 35mm or digital pinhole photography under bright lighting conditions. Usable for digital infrared work.

• 1/15-1/2 second — These speeds allow existing light photography under dim lighting conditions. They also allow you to soften the flow of a moving stream or waterfall. Usable for digital infrared work under bright conditions.

• 1/30 second — About the slowest shutter speed for hand-held use with a wide-angle lens. Usable for digital infrared work under bright conditions.

• 1/60 second — This is a good general purpose shutter speed, usually the lower limit for handheld use with a normal lens, and a setting most often associated with indoor or flash photography.

• 1/125 second — This is a fairly worry-free speed when using standard zoom lenses.

• 1/250 second — This is usually the maximum speed at which you can sync to a flash.

• 1/500 second — Good for use in bright sunlight, or with most telephoto lenses.

• 1/1000-1/4000 second — These speeds allow the photographer to freeze motion, such as in sports.

Shutter speed plays a minimal role in flash photography. As long as the shutter remains open for the duration of the flash, it does not affect the exposure significantly. However, many cameras have a “slow sync” feature which allows some ambient light to influence the exposure. Also known as “fill flash” this can help to achieve a more natural exposure while reducing the dark shadows created with backlit scenes.

Automatic exposure cameras that have a Shutter Priority mode allow the user to select a shutter speed, while the camera selects the corresponding aperture speed for the proper or desired exposure. This allows for more predictable results when shooting in low light.

The Aperture

The aperture of a lens is a variable size opening which controls how much light enters the camera. It is one of two elements of exposure, the other being shutter speed. But the aperture doesn’t only affect the exposure; it also affects sharpness and depth of field, two important aspects of creative control within the scope of photography.

Apertures are designated by “f-stops”, and written as a ratio (1:2.8) or as an f-number (f/2.8) The smaller the number, the larger the opening and the more light enters the camera. The larger the number, the smaller the opening and the less light enters the camera. Starting from the widest aperture, each successive full stop lets in half the light of the previous stop. Some lenses have half-stop clicks, others only full stops. Digital cameras can typically select between half stops and one third stops through the camera’s software.

Apertures can be set with a variety of different controls. On most cameras, a ring or lever is located on the lens that rotates or moves to increase or decrease the aperture size mechanically. In the case of a digital SLR, a dial or thumbwheel is used to set the aperture electronically, while compact digital cameras may do this through a system of menus.

Every lens has a range of apertures, from one (for a simple, fixed-lens camera) to many (seven or more for a typical interchangeable SLR lens). Normal lenses typically have apertures ranging from f/1.4 to f/22. However, a compact digital camera may have a range of only f/2.8 to f/5.6. Simple or “toy” cameras might have two or three apertures, while “fixed-focus” cameras typically use smaller apertures for greater depth of field.

Depth of field is the width of the plane of sharp focus, from front to back. Narrow or shallow depth of field means that if you focus on the eyes, the nose and ears might be out of focus. Wide or deep depth of field means that not only will the nose and ears be in sharp focus, but elements both in front of and behind the face, within a reasonable proximity. Control over depth of field means that when taking a portrait, a distracting background can be thrown out of focus. It gives you the ability to isolate or separate your subject from its surroundings.

Sharpness is the maximum resolving power of the lens. With a truly sharp image, the greater you magnify the film negative or digital image, the more detail you will see, up to the limit of the pixels or film grain. Maximum sharpness is limited by the design and quality of the optics, and also by the effects of diffraction.

Diffraction is the tendency of parallel light rays to disperse when passing through an aperture. Normally the amount of dispersion is negligible. But beyond a certain point, the amount of diffraction exceeds the circle of light projected on the film or sensor, softening the image. The only way to overcome this is to increase the size of the film or sensor. Diffraction is the reason compact digital cameras with smaller sensors are limited to about f/5.6. Smaller than that, and image resolution would suffer greatly.

Different apertures produce different effects, based on degrees of depth of field and sharpness, and it’s important to know what these effects are. Which of the available apertures the photographer can use depends on several other factors; the shutter speed range of the camera, the ISO setting of the camera, and the available light.

• f/1.2, f/1.4, f/1.8 — These apertures allow you to take photos in existing light without the use of flash, while minimizing motion blur. However, while they may not yield the sharpest images, their narrow depth of field affords you the greatest ability to isolate your subject from the foreground and background.

• f/2.0, f/2.8, f/4.0 — These apertures provide a good combination of sharpness and speed, with the ability to isolate your subject within the narrow plane of sharp focus. They require precise focusing.

• f/5.6 — An aperture available on most cameras and lenses, offering a good combination of speed and depth of field. Often the aperture at which most lenses are their sharpest. Focusing is less critical.

• f/8.0, f/11 — When there is adequate light, these are ideal apertures to use, giving high degrees of both sharpness and depth of field. f/11 is about the smallest aperture you can use before the effects of diffraction begin to degrade sharpness. A single focus setting will cover a wide range of distances. Many fixed-focus cameras use f/11.

• f/16, f/22 — When extreme sharpness is not a priority, but the need to avoid critical focusing is, these are the apertures to use. Everything from about 4ft. to infinity will be in focus, although not at maximum sharpness.

The aperture plays a major role in flash photography. Apart from the flash’s intensity and duration, the aperture is the sole means of controlling flash exposure.

The shape of the aperture is a consideration, as it has a direct affect on the bokeh. Some apertures use an iris with rounded blades which create a more circular bokeh. Others use a higher number of blades to create a smoother circle. Lenses with apertures consisting of “waterhouse stops” (interchangeable disks with varying-sized openings) can use custom shapes which will determine the shape of the highlights.

Automatic exposure cameras that have an Aperture Priority mode allow the user to select an aperture, while the camera selects the corresponding shutter speed for the proper or desired exposure. Aperture priority is the most popular auto exposure mode due to its ability to allow the user to control depth of field.

Aperture Guide

A quick guide to apertures available on the Nikon D90, in 1/3 stop and 1/2 stop increments:

f/0.95 f/1.0 f/1.1 f/1.1 f/1.2 f/1.4 f/1.6 f/1.6 f/1.8 f/2.0 f/2.3 f/2.3 f/2.5 f/2.8 f/3.2 f3.3 f/3.5 f/4.0 f/4.5 f/4.8 f/5 f/5.6 f/6.3 f/6.7 f/7.1 f/8.0 f/9 f/9.5 f/10 f/11 f/13 f/13 f/14 f/16 f/18 f/19 f/20 f/22 f/25 f/28 f/29 f/32 f/36 f/39 f/42 f/44 f/52 f/58 f/61 f/64

These values, for the most part, have been taken directly from the camera. Some of the 1/2 stop values, when rounded by the camera, are the same as the 1/3 stop values. Using this chart, we can see for example, that an f/1.2 lens is a full stop faster than an f/1.8 lens, but an f/1.8 lens is only 1/3 stop faster than f/2.0. However an f/1.8 lens is a significant 1-1/3 stops faster than an f/2.8 lens, a common aperture value. The holy grail of speed, the f/0.95 lens, is just slightly over a full stop faster than an f/1.4. Using Nikon’s claim of a 4-stop advantage using VR, the 16-85mm f/3.5-5.6 would behave similarly to an f/0.95-2.0 lens in cases where it was not used to stop action. In reality however, it would be closer to f/1.2, a three-stop advantage. Not too shabby. On the other hand, the 70-300mm f/4.5-5.6 would be the equivalent of f/1.6-2.0. Still not shabby. So, unless you are shooting sports or other action, purchasing a fast f/2.8 telephoto may not be entirely necessary. It will however cut down significantly on flash recycle times, which may be a consideration.

Walker Evans once said, “People always ask me what camera I use. It’s not the camera, it’s … ” and he tapped his temple with his index finger.

Video on the Canon Powershot SD780 IS

I’ll level with you; I’m not a video person. It’s never held that much of an attraction for me. But even I have to admit that I’m fascinated by the fact that pretty much all still digital cameras come with some form of video. And the Canon SD780 is pretty amazing in this regard. In fact, it was a deciding factor in its purchase.

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Restoring Lost Images

Every once in a while, the situation arises when your images seem to be gone. Or, you accidentally delete images that you meant to keep. Or, You accidentally format a memory card without offloading all the images. Here’s how to restore them.

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The Pitfalls of Pixel Peeping

Pixel peeping is often used as a derogatory term to described those obsessed with zooming into digital images to scrutinize them on a pixel-by-pixel level. While pixel-peeping can be useful in evaluating lenses, no good can come of it when done as a matter of course.

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First Impressions: AF Nikkor 20mm f/2.8D

I finally received my Nikkor Ultrawide prime today. I’ve been debating this purchase for a while now, but if I’m going to have at least one AF-D lens in my collection, it might as well be the most compact of them all and be compatible with a wide variety of bodies and uses.

It seems that, for a lens of this price range, a pouch should have been included. It was conspicuously absent from the box, as was the bayonet lens hood. But then, this is a different class of lens altogether.

First off, this lens is made in Japan. Not that I feel that products manufactured in Thailand, Korea or China are of poor quality. But this lens is made in Japan.

Secondly, it’s fully mechanical, not electronic. Yes, it has a chip to tell the camera what type of lens it is, and to relay the focus distance information for 3D matrix metering, but that’s it. When you look inside the focus scale window, you see a metal focus scale with etched, paint-filled numbers, directly coupled to the rubber-covered focus ring. This direct coupling makes all the difference. It gives the focus a silky-smooth feel with hard stops at 0 and infinity. Silky smooth, but not damped. Damping the lens would interfere with its autofocus operation, so it’s the first thing to go. But this lens is, for all intents and purposes, a traditional lens.

I like the simplicity of the older autofocus system. A simple mechanical linkage, driven by the camera, simplifying the lens. I can see now why this lens is as compact as it is. But, I can also hear the case for the built-in Silent-Wave motor. This lens is L-O-U-D. Fast, but loud. When traveling from one extreme to another, you can really hear it go. But, that’s not particularly field-relevant, because in actual use, the travel is usually quite short, emitting just a brief chirp.

This lens give new purpose to the two-position AF-M switch at the base of the lens. Doesn’t do much with a G lens. But with a D lens, it decouples the focus linkage, allowing fully manual focusing, as well as electronically disabling the motor.

Sadly, this is the worst mounting of all my lenses. It goes on with all sorts of grinding sensations, although I  can find no physical evidence as to why. But, once it’s on, it fits nice and tight, with no play whatsoever. The body of the lens just barely provides enough surface area to grip it while mounting. I would definitely NOT recommend using the focus ring’s infinity stop to aid in this operation, although I would think the f/22 lock on the aperture ring would be OK. The additional surface area of the aperture ring definitely helps.

It’s a good idea to decouple the focus linkage using the AF-M switch before mounting any D lens. If you do accidentally slip and turn the focus ring, it won’t turn the motor and gearing in the camera.

On the D90, it looks and feels great. Proportionally it’s just right, although it would dwarf a D40 or D60, and on a D3 it would just about hold its own. Its outward taper gives it a solid, professional look, and its short focal length makes it compact and easy to focus. A lens you don’t mind keeping on your camera at all times. Tricky to keep your hand off the focus ring in autofocus mode, but the body is long enough to grip if you like to steady the camera that way.

The field of view is perfect on the D90. At a full-frame equivalent of 30mm, it falls between that golden 35mm, and the superwide 24mm, very usable indeed. Actually, the diagonal measurement of the APS-C sensor is 30.5mm making this a true “normal” lens, just as 43mm is on a full-frame camera. The DX crop factor uses the most accurate part of the lens’ field of view, so the edges are sharp and free of any noticeable aberrations.

To be honest, I don’t see myself owning a lot of D lenses, so If I only have one, this seems to be a good choice. If the impeccable Nikkor AF-S DX 35mm f/1.8G wasn’t 1-1/3 stops faster and so darn cheap, I’d probably forgo it for this lens.

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Tech Notes:

• The 20mm f/2.8D has a bayonet lens hood mount, which accepts the Nikon HB-4 Bayonet Lens Hood.
• On the D90, the Hoya 67mm adjustable lens hood can be used in its intermediate position with a 62-67mm step-up ring.
• On a full-frame camera such as the N80, neither the 67mm nor the larger 72mm Hoya adjustable hood can be used even at their widest settings without minor vignetting.

Review: Samyang 500mm f/8 Mirror Lens

Samyang/Phoenix 500mm f/8 Mirror (Catadioptric) Lens

Mirror telephoto lenses, often referred to as reflex lenses but more accurately called catadioptric lenses, are frequently misunderstood and mistaken for poor quality. In reality, the catadioptric system is an ingenious telephoto design which reduces size, weight and cost when compared to refractive designs of similar focal length. Optically, it virtually eliminates chromatic aberration. But, like all advantages, they come at a price.

At any give price point, any lens design design represents a compromise. Make a lens longer, and you sacrifice sharpness, speed and contrast. At higher price points, these sacrifices are reduced, but come at the price of increased size and weight. So, it naturally follows that any lens design that packs so much power into such a small package and at a reasonable price will be subject to the limitations of physics.

That said, the Pheonix/Samyang 500mm f/8 MC Mirror lens is somewhat of a feat in optical design.

Ignorance is Bliss
In 1976, when I purchased my first SLR, the Canon AE-1, I pined after the Canon Reflex 500mm f/8. I was intrigued by the donut-shaped bokeh that it produced, seeing it as a unique advantage that no other telephoto lens had. Since then, I’ve always had an affinity the aesthetic of reflex lenses.

Interestingly, while some complain about the quality of the reflex len’s bokeh, others seek to produce creatively shaped bokeh using custom aperture disks. Lensbaby even offers a creative aperture kit for their Optic Swap series of lenses.

I passed up several opportunities to purchase the reflex lens for my Canon AE-1, which of course would have been unusable with my present Nikon Bodies.

Newer, Cheaper, Better
Fast-forward to 2010. By comparision to the reflex lenses of old, the Phoenix/Samyang version is smaller, lighter, has a shorter minimum focus distance, and is quite inexpensive. For about a hundred dollars, you can purchase a lens which will enable you to capture images that no other lens can.

Mounted to my Nikon D90, this lens is about the same dimensions as the fully retracted Zoom-NIKKOR 16-85mm f3.5-5.6, and weighs in at 4.3 oz. less. It’s focal length however is 750mm, a 588% increase over the Nikkor! At 127.5mm, the Nikkor is actually 1-1/4" longer, and costs over $490.00 more than the Phoenix/Samyang.

In use, it’s solid and simple. It’s satin-black anodized, all-aluminum construction is a nice departure from plastic, and the etched, color-coded, paint-filled markings harken back to the days of old. The focus ring is silky-smooth and heavily-damped, which aids in critical focusing. Once the T-mount adapter is installed and adjusted so the index mark is at top-dead-center, it mounts like any other manual focus lens.

Operation is straightforward; set the camera to manual, select an appropriate ISO/shutter speed combination, focus and shoot. If you rely completely on auto exposure and auto focus, you will find this challenging, perhaps even daunting. But, if you have experience with traditional photography, you will have no problems outside of the fact that you are attempting to hold the camera steady at 750mm. The situation would be the same if you were using a 750mm manual refractive telephoto lens. Except that you would have paid over $3,000.00 used, and be toting around something that weights 6 lbs., 10 oz. and is over 15" long.

Build Quality ★★★★★
Solid, all-metal construction, but extremely lightweight due to smaller refractive optics. Black anodized aluminum with engraved, paint filled markings. Useful focus scale.

Focus ★★★★★
Silky smooth and heavily damped to avoid accidental movement. Wide rubberized focus ring with long travel to assist focusing. Works well with AF confirmation lamp. Razor-thin depth of field not for the faint of heart. There’s no hard stop at infinity focus, and if you consider this to be the point where the index mark aligns dead-center with the infinity symbol, then the focus scale is very slightly off. However, this is not field relevant, and well within acceptable limits for a T-mount lens.

Optical Quality ★★★
When properly focused, using an adequately fast shutter speed and/or tripod, this lens is amazingly sharp for a $100.00 piece of glass. The images from a mirror lens have a soft quality even though they are tack sharp, which can be deceiving at first. However, they are conspicuously void of chromatic aberration, making them very clear. Given a little effort, it is not difficult to coax excellent images from this lens. But it may simply be impossible to get any closer to the subject, or fork up any more cash. And this is were this lens shines.

Value ★★★★★
Tons of fun and well worth the measly $100 or so dollars. To sweeten the deal, it comes with three 30.5mm filters that attach to the rear of the lens; a skylight filter, an ND-2x and an ND-3x. While the skylight filter has a warming effect, sadly it provides very little UV suppression having failed the black light test. There are actually quite a few 30.5mm filters available, especially those suited to black and white photography.

Versatility ★★★★
With the appropriate T-mount adapter, this lens will fit any SLR, 35mm, full-frame or APS-C! Works particularly well with DX DSLRs, where it’s focal length is 750mm but the aperture is still f/8! Good for nature photography and exploring distant, out-of-reach objects, but it’s not for sports!

Diaphragm
Fixed at f/8.

Filters
72mm (front), 30.5mm (rear).

Hood
Not included, but badly needed. The Hoya 72mm Screw-in Rubber Zoom Lens Hood is highly recommended.

Included Accessories
Vinyl storage pouch, front lens cap, rear cap, three 30.5mm filters; Daylight, ND-2X, ND-3x

Specifications
You can view Samyung’s Specifications for this lens by visiting their website.

Recommendations:

• Use a Tiffen 72mm Low-Light Warming Polarizer to increase contrast and saturation; This is an ideal filter for this lens as it’s inexpensive, suppresses UV radiation, and adds only one stop to the exposure.


• For general protection, use the Hoya 72mm UV(0) Haze filter. This inexpensive, single-coated filter is more effective than the newer UV(0) S-HMC filter manufactured in the Philippines.


• Use a Hoya 72mm screw-in rubber zoom lens hood to increase contrast and reduce flare. With the appropriate step-up rings, this hood is ideal for all your other lenses as well, as it adjusts for three different lens focal lengths.


• If you prefer to use rear-mount filters, try the Tiffen 30.5mm UV Haze 1 filter. This filter has proven effective in suppressing UV, and is quite inexpensive. Although it is possible to purchase a 30.5mm polarizer, there would be no practical way of adjusting it once the lens is mounted.


• Motion blur may be more distracting than noise, so use a higher ISO when warranted. Noise can be reduced in post processing, but motion blur cannot.

Picture Taking
Being almost as compact, but a little lighter than a standard zoom, it’s a joy to carry to carry around. Because it’s so small, people don’t realize you’re shooting with a very long telephoto, so you operate in a kind of stealth mode. This makes it possible to capture candid portraits without the subject knowing…great for street photography. It also enables you to capture the intimate details of distant objects, or fill the frame with objects that are very far away. Focusing is challenging, but aided by the fact that the focus confirmation works quite well, despite it only being rated for lenses of f/5.6 or faster. It helps to judge the distance by eye, and dial it in on the focus scale before composing the subject. Then, it’s just a matter of fine tuning.

It’s easy to mistake lack of sharpness with motion blur, so be sure to work with a shutter speed fast enough to overcome the shakes. 1/500th sec. works well, despite the effective focal length of 750mm on the DX format, and I’ve shot as low as 1/250th with good results. A monopod certainly helps, as does the technique of bracing the camera against a stationary object.

For nature photography, a tripod works well, even if not locked down to enable free panning, It’s the minute oscillations of hand-holding that wreak havoc, which the tripod and monopod tend to suppress. A steady hand and the body’s own ability to damp vibration are techniques that have been all but forgotten, but are most relevant here. And the mass of the camera/lens combo also plays a significant role. Due to the lens’s light weight, you might want to use a grip with heavy, high-capacity NiMH batteries installed to add vibration-dampening mass if shooting in low-light conditions.

Flash is not at all out of the question, and can be used as fill if shooting within range. However, your stealth ability goes out the window, and you may need to use it in manual mode. Not a problem with the D90, as the on-board flash allows me to dial in the precise power needed in 1/3 stop increments, as would an external flash. Plus, an external flash in good ol’ auto-aperture mode reduces the need to adjust manually.

This lens takes on a whole new purpose with digital photography. It’s subdued contrast and saturation can easily be enhanced in post-processing. If you shoot in camera raw, you can underexpose the images slightly to reduce motion blur, and increase the exposure in post. When it comes time to upgrade, this lens will only get better. Higher ISO capability in your next camera means sharper, images with less motion blur.

Although not particularly exciting, here are some sample images:

Cable Conundrum. Handheld from about thirty feet away. If I had used a tripod, the smallest type would have been legible.

Security Light. Handheld, about fifty feet away. If you look closely, you can see the wire embedded in the glass behind the metal grill.

Suburban Safari. Handheld, braced against a building. A life-size elephant statue, from about 100 feet away.

Halloween Skull. Handheld from about ten feet away, indoors, built-in flash. Proof positive that this can do macro.

Except for a fifty percent reduction in size to make them web-friendly, these images have not been post processed. However, they all respond very well to added contrast, saturation and sharpening, especially with Adobe Photoshop Camera Raw or Apple Aperture, which both apply the changes as metadata without permanently affecting image quality.

I must admit, I’m at a slight disadvantage with the D90. If this were a D300S or above, I could enter the lens information manually and have full metering capability. But it’s OK for now, as I have Chimping to fall back on. My next body will probably be the successor to the full-frame D700, and that will allow me to take advantage of full matrix metering.

Nikkor 16-85mm f/3.5-4.5G: Six Primes in One

The AF-S DX Nikkor 16-85mm f/3.5-4.5G ED VR has six ideal focal length designations on the barrel, which are my go-to numbers. Although DSLR zoom lenses are continuously variable, I find myself going straight to these numbers first, depending on the subject matter. Generally, I set the lens to 24mm, which gets me closest to the classic 35mm focal length. For portraits, I tend to work around 50mm. Starting from the short end:

Nikkor 16-85mm f/3.5-5.6	35mm equivalent	f-stop range
16mm	24mm	f3.5-f22
24mm	36mm	f/4.0-f/25
35mm	52.5mm	f/4.5-f/29
50mm	75mm	f/5.0-f/32
70mm	105mm	f/5.6-f/36
85mm	127mm	f5.6-f/36

Like the Canon SD780 IS and Nikon P5100, the maximum and minimum apertures are variable depending on the focal length of the lens. At 85mm, it goes all the way up to f/36! This is not as great an advantage as it seems though, since diffraction begins to soften images above f/11. To get the best combination of depth of field vs. sharpness, work between f/8 and f/11.

Remember the old photojournalists’ saying, “f/8 and don’t be late”.

On the other hand, f/5.6 is a memorable number, as it’s available across the board, and gives good all-around results regardless of which focal length you use. Happily, as long as you don’t manually change the aperture, the D90 returns to the maximum aperture for any given focal length automatically as you zoom back out. But if you change it, it sticks, which is one reason I like to work with a single focal length whenever I can.

Prime lenses such as the Nikkor 20mm f/2.8D, 35mm f/1.8G, 50mm f/1.4G, and 85mm f/1.4G all have distinct advantages in both size and speed over the Nikkor 16-85mm, but VR narrows that gap somewhat. In theory, at 35mm, VR makes the 16-85mm behave similar to f/1.8, (except for the ability to freeze action), but it can't compete with the compactness of the 35mm f/1.8.

Canon Powershot SD780 IS: Seven Primes in One

The Canon has seven steps as opposed to the Nikon P5100’s nine, and they’re pretty similar. Starting from the short end:

Canon Powershot SD780 IS	35mm equivalent	f-stop
5.9mm	33mm	f/3.2
7.2mm	40mm	f/3.5
8.7mm	49mm	f/4.0
10.6mm	60mm	f/4.5
12.5mm	70mm	f/4.5
14.8mm	83mm	f/4.8
17.9mm	100mm	f/5.8

Unlike the Nikon, The Canon doesn’t report the 35mm equivalent focal length in the EXIF data, so I had to calculate it. Camera manufacturers have always varied features between brands, but with digital you can expect even more differences. There are no standards other than industrial design common sense, and camera companies have egos just like any other. Happily, the multi-selector on the Canon controls the exposure compensation, flash mode, self-timer and AF focus range just as it does on the Nikon except that it’s rotated 90° counter-clockwise. I’m actually surprised the icons have been as consistent as they have.

The Menu button on the Canon behaves like the Setup mode on the Nikon, and the Func. Set button on the Canon like the Menu button on the Nikon. It works out OK, because you can get to both quickly with just your thumb. The Nikon requires your left hand and a trip to the Mode Dial on top of the camera. It’s a very different kind of camera, just as a rangefinder is from an SLR. There’s no one perfect camera and I like working with the different designs.

Thank goodness these functions are not touch-screen controlled. If they were, I wouldn’t have bought this camera. If I want touch control, I’ll use my iPhone, thank you very much.

Here are some test shots:

The Morning After:
Looking east from 7th Avenue, Manhattan

Fall Foliage

Times Square at Night

I’m fairly happy with existing light results. Even at low ISO the images are somewhat grainy, so the results at ISO 1600 don’t seem as bad. They’re still much sharper than they would ever be with the closest sized film camera, which would probably use 110 film.

Just in Time for Christmas: My ELPH Story

My very first childhood camera was a Keystone 125X, a little plastic brick that took 126 film cartridges, and served me well on class trips to the Museum of Natural History. When it came time to upgrade, I saved up for a Kodak Pocket 110. Slim profile, sliding lens cap, thumb-operated  film advance lever; at about an inch thick, I could actually slip it into a pocket. This was the camera for me.

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First Impressions: Canon Powershot SD780 IS

As I remove the tiny device from its ecologically friendly packaging, the first thing I notice is its heft; It’s solid and substantial. If feels like a real camera, and yet it seems too small to be a real camera.

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New Arrivals: Canon Powershot SD780 IS

Canon Powershot SD780 IS, Rear

Received this just as I was on my way out, so I’ll have to wait until tomorrow to try it out…

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The Next Digital Holga?

Pentax Optio H90; The Next Digital Holga?

OK, so although the Yashica EZ F521 was slated to be a “digital Holga”, its limited availability in the US may have generated a false start. After all, by definition a Lomographic camera must also be a camera for the masses; if the masses can’t purchase it readily, then what’s the point?

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Reviewing images without extending the lens on the Nikon Coolpix P5100

Here’s a little trick I discovered when reviewing images on the P5100:

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Nikon Coolpix P5100: Nine Primes in One

In a world where I’m pining after a rangefinder, my Nikon Coolpix P5100 gets better and better as I learn how to use it.

Today is the annual Halloween Parade at my daughter’s school, and this year they’re going to march down the sidewalk outside the school. I’m torn between shooting with the Nikon D90+Voigtländer Ultron 40mm, or the Nikon P5100. My concern is that the P5100 won’t be fast enough. Or, that I won’t have as much control.

So, I did a quick test, and under cloudy conditions with the AF (“infinity”) focus mode, the shutter lag is only about a second. Since the camera does not indicate the focal length in numbers, and I prefer to use the viewfinder with the LCD off, I shoot some test images to see just what the focal lengths are. Each quick flip of the zoom lever advances an apparently repeatable step, so I take a shot for each step, pull the card, and read the EXIF data. These are the results, starting from the short end:

Nikon Coolpix P5100	35mm equivalent	available f-stop range
7.5mm	35mm	f/2.7-7.6
8.5mm	40mm	f/2.9-7.1
10.1mm	47mm	f/3.1-7.7
12.9mm	60mm	f/3.5-7.7
15.7mm	74mm	f/3.9-7.6
18.6mm	87mm	f/4.3-7.5
21.5mm	101mm	f/4.7-7.3
24.5mm	115mm	f/5.1-7.9
26.3mm	123mm	f/5.3-7.3

It’s like having nine primes in one! Zoom all the way in, and three or four clicks out and I’ve got my (approximate) 90mm and 75mm portrait lengths. Zoom all the way out, and two clicks in, and I’m shooting normal at an almost ideal 47mm. Now, I feel as though I have some control.

I can use aperture priority with f/5.4 (closest to the very versatile f/5.6) in every zoom range, and for maximum depth of field, f/7.6. At a “normal” focal length, I’m around f/3, and at portrait, I’m around f/4. All these numbers are not far off from the NIKKOR 16-85mm f/3.5-5.6 zoom. For some strange reason, the aperture does not remain constant, but varies slightly. I can deal with that though.

Shooting with the viewfinder takes a little courage, but becomes comfortable very quickly. The camera knows to turn on the LCD each time you change something; the aperture, exposure compensation, auto-focus mode, flash preferences, self-timer, etc. As soon as you push the shutter release halfway, it turns off. You can turn the LCD off in the P, A, S, and M modes, but in all other modes it stays on. This is fine, and seems pretty logical. The P, A, S and M modes are for serious shooting, and the other modes for casual shooting.

“Mirrorless” is the new “Rangefinder”

A New Breed of “Mirrorless” Digital Camera: The Fujifilm Finepix X100.

A new breed of camera has been slowly emerging from the ashes of the Rangefinder; The “Mirrorless” digital camera.

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Just in Time

Canon PowerShot SD780 IS:
A Never-be-without-a-camera-again Camera

So here I am, looking in a shop window in Manhattan on the way to a gig as I come across the Powershot SD780. It was not far from an SD1200. And I notice both have optical viewfinders.

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Get ’Em While You Can

So smitten am I with the Janco 3-Color Pop-Up Flash Diffuser that I decided to order a second one as a backup. At its low price, why not.

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Scanning Holga Images

This morning I’m scanning some 6x6 Holga images from my first test roll. I’m quite impressed with the results. Sharp in the center, nice vignetting, nice grain, nice softness and chromatic aberration around the borders. The film stock was expired Kodak VPS 160.

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Small-Format Pinhole Revisited

This morning I finally ordered the drill bits I need to make some pinholes. Even though I’m very happy with my Lensbaby pinhole optic, I can get wider with a body-cap pinhole, which is also much more compact.

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Autumn in Didymia

The autumn leaves are peaking this week, so today was a good day to give the didymium filter a try...

The filter has a natural mauve cast, so I tried a custom white balance through the filter to neutralize it. It skewed everything towards the reds, diminishing the separation between the reds and the greens. When both warm and cool colors are present, using the standard daylight white balance gave an optimal effect.

New Lens, New Moon

Taken with NIKKOR 70-300mm Zoom, enlarged and sharpened.

I was excited to see how a moon shot would turn out with the Samyang/Phoenix 500mm cat lens, and tonight was clear enough to give it a try.

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Shooting 35mm with the Holga 120

There’s a 35mm film adapter kit available for the Holga 120 which enables you to take standard 3:2 35mm frames. It includes a 36mm x 24mm mask, and a back with the frame counter window covered up. The mask has two plastic brackets on the left side to center the film cartridge, and guides to ensure that the film remains centered on the mask opening. You use the original 120 take-up spool with no additional modifications.

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The Annual Autumn Tradition

Today my family and I will be embarking on our annual autumn tradition; a pumkin-picking pilgrimage to Alstedes in Dover. It seems the perfect opportunity load my Holga 120FN with 35mm film and test out the new .5x Wide Angle Adapter.

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How to Build a Grid Spot

I love to build stuff. It’s one of the many reasons I love photography. Every lighting situation is an opportunity to make a new gadget. So it stands to reason that after following Strobist for a while I’d find a kinship with them in the building of light modification devices for flash. And perhaps the most cool is the grid spot.

Thanks to Strobist, I was able to find a source of black Coraplast in manageable quantities. In case you didn’t know, Coraplast is basically corrugated cardboard constructed out of plastic, available in colors. You’ve most likely seen it as those silkscreen screen-printed campaign signs posted on folks’ front lawns. The hollow core forms narrow tubes through which light can pass in a narrow beam. You cut it into narrow strips perpendicular to these tubes, and laminate them into a flat panel, like this:

The greater the thickness, the narrower the overall beam, constructed of many smaller beams. One-inch is a good starting point. Grid spots, or grids as they are also known, essentially do the same thing as a snoot, but offer more control and are more compact. The challenge was to design mine in such a way that it can fit all the flashes I don’t have yet. And with the help of a friend who loaned me his Vivitar 285HV (probably the largest scenario) and Nikon SB-600 (probably the hardest to fit due to the projection on the top) I came up with the design above. The outer panel on the left is made 3/4" longer than the rest to form a tab which you can use to rubber-band it to the flash. I did’t want to attach it with something that wraps around the back of the flash, as there seemed to be too many variables to overcome, such as the size of the flash, and the angle of bounce, if it’s to be used. I’ve notched the corners so that the tab is slightly narrower than the flash head to make for a more secure fit.

The Vivitar 285HV not only has a large flash head, but its bezel is also very narrow. So, if I could make it fit this flash, it should be able to fit anyting else. And it does.

Coraplast Grid on Vivitar 285HV

Coraplast Grid on Nikon SB-600

The projection at the top of the SB-600 may at first present a mounting challenge, but in reality it creates an advantage; you could make slight adjustments to the vertical tilt if necessary by using the projection as a pivot point. Here the angle has been adjusted ever-so-slightly upward.

Detail: Using the Wide Angle Adapter projection as a pivot point. 

Of course, being a designer, the raw edges of the coraplast on the sides drove me crazy. So, I simply wrapped a 1-1/8" band of self-adhesive black craft foam around the whole thing. The extra width provide a slight rim around the front and back sides to give it a finished look and hide imperfections.

Not only does it fit these flashes, but also the D90’s on-board flash via the Janco flash diffuser bracket. You just insert the bracket into the appropriate holes. It fits perfectly.

Grid mounted directly on D90 using a Janco Flash Diffuser bracket.

For me, this was the icing on the cake. It gives me a level of control from the camera’s flash I would never have expected. A quick test shot reveals some dramatic lighting effects:

Taken at a distance of about five feet, with the grid mounted directly to the D90.

So now that I know a single design can meet the requirements of all my proposed flash purchases, I just have to duplicate it in multiple thicknesses for different beam spreads. I’m thinking a half-inch, one-inch, and two-inch version. Perhaps a four-inch version for pinpoint lighting. Perhaps experimental designs (what if every other row was blocked off, or random cells plugged?)

What’s next, a light diffuser made from Tupperware?

Hmmm...

Strobism

For the past couple of weeks, I’ve been following strobist.blogspot.com and getting a feel for flash. I’m still working out my flash strategy, and it will likely be based on the Strobist concept. So far, I’m fully in sync with David Hobby’s preachings. Travel light, and work with what you’ve got. So I’m approaching flash cautiously, since again I need to purchase all new equipment. Well, almost

Eventually I’ll be needing two or three light stands, and I’m happy to find that in my original stash I have a nine-foot Smith-Victor stand, and two Manfrotto umbrella adapters with hot-shoe adapters. So, I’ve got a little bit of a head start.

With ten sheets of black coraplast in hand, I’ll be building a few grids, snoots and flags.

Then there’s the flash purchases themselves. I’m pretty much set on the Nikon SB900, since it will work not only as an excellent iTTL flash, but also as an off-camera flash. The very affordable SB600 would be my second flash, due to its compatibility with a wide range of Nikon cameras, including the N80. It has both i-TTL and D-TTL, plus TTL Auto and manual.) For a second backup/third flash I’m considering the Vivitar 285HV, and for Macro work the Sigma-EM 140 DG Macro Ring Flash.

For times when I absolutely, positively have to use flash on-camera, the Custom Brackets CB Junior rotating bracket wins hands down.

First Impressions: Samyang 500mm f/8 Mirror Lens

Samyang/Phoenix 500mm f/8 Reflex (Catadioptric “Mirror”) Telephoto Lens

Those who may think this is a poor quality product are sadly mistaken. The truth is, this lens is manufactured to high-quality standards with a fit and finish comparable to any high quality lens.

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New Arrivals: Holga .5x Wide Angle Adapter

Wow, a two-element plastic wide angle lens for my Holga 120FN. Now I can comfortably shoot 35mm film with the 35mm film adapter (mask and back), or as panoramic sprocket-hole with the modified 6x6cm mask.

It slides right over the existing lens covering the distance scale, which is OK, since it’s meant to focus at infinity anyway. It even comes with its own storage pouch, and front and rear caps.

New Arrivals: Samyang 8mm f/3.5 & 500mm f/8

I just unpacked my Samyang long and wide duo. The long is the Phoenix 500mm f/8 Catadioptric (“Mirror”) lens, and the wide is the ProOptic 8mm f/3.5 Fisheye lens. Both are manufactured in Korea by the Samyang company, and are marketed under many other brand names as well.

When it comes to equipment I’m very picky about quality, and the build on these lenses is outstanding. Both are manual focus, unchipped lenses, so they won’t even allow me to use any of the auto exposure modes on my Nikon D90. But this is just fine for the type of work I’ll be using them for. Besides, what’s better than a digital camera with a color histogram?

Full Moon Tonight

Handheld shot of the moon, AF-S NIKKOR 70-300mm f/4.5-5.6 IF-ED.

Taken just moments ago. It seems to be a good test of any telephoto lens to attempt this. This was taken with the Nikon AF-S NIKKOR 70-300mm f/4.5-5.6G IF-ED at 1/400s, f/8, ISO 200, handheld. At the long end, it’s 450mm on the D90. Thank goodness for VR, not that shooting at 1/400 sec. is that challenging. The moon is so bright that you can shoot this fast with a low ISO and relatively small aperture to capture all the detail.

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Photoshop Giveth, and Photoshop Taketh Away

Black-Eyed Susans, In the Lomographic style

Yes, you can remove lots of ills with Photoshop, but you can also use the same tools in reverse to add those same ills in were they didn’t originally exist. This photo is an example of that.

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Macro on the Cheap, Part II

Reversing a wide-angle lens with a reverse mount adapter is a pretty neat and inexpensive way of creating a manual focus, manual exposure macro setup without buying more lenses. The flip side to that is creating an auto-focus, auto exposure macro setup which is more convenient, albeit at the expense of speed.

Typically this is done by reversing a 50mm lens and attaching it to an existing auto exposure and/or auto focus lens. As with mounting the lens directly to the camera body in reverse, the wider the angle, the greater the magnification. However, this technique is prone to vignetting which may increase as the angle gets wider.

What we need to do this is known as a reverse coupler, a simple device with two male filter threads which allows you to attach two lenses front to front. The reversed lens behaves just like a closeup lens that screws onto your filter threads. A multi-element, multi-coated, high-diopter, closeup lens.

It works like this; if you add a magnifying (convex) lens in front of your main lens, it shortens the minimum focusing distance so that in order to achieve focus, you need to move closer to the subject. When you do, the subject is magnified in the process. Since a normal lens gathers light from the scene and reduces it to fit onto the camera’s film frame (or sensor) flipping it around has the opposite effect…it becomes a magnifier!

To figure out the diopter value, divide 1000 by the lens’ focal length. So, a 50mm lens would have a diopter of 20. Compare that to a stack of three typical closeup lenses which would give you a total diopter of 8, and degrade image quality with significant chromatic and spherical aberration.

Since this technique often produces vignetting effects, you might want to test your intended “diopter” lens first by “freelensing”; hold the reversed lens up to your main lens with the aperture wide open to see if the image circle is reduced significantly. Setting the “diopter” lens to its shortest focus distance will enlarge the image circle, but reduce the working distance. Also, make sure all filters are removed from the facing filter threads to reduce the lens-to-lens distance as much as possible.

The Nikon BR-6 Auto Diaphragm Ring helps here as well. Even though you won’t be using the aperture of the “diopter” lens, you can use the BR-6 to set it to its widest position, and add a filter to protect the rear element.

Color Management

In the world of professional imaging, known in these hi-tech times as premedia, color management is king. And, as a consumer, amateur or professional photographer, it’s equally important for you to know your way around this subject in order to achieve the level of quality you are expecting.

Color management, simply put, is the ability to adapt different capture devices with different color characteristics to different output devices, also with different color characteristics. This is achieved through ICC color profiles, data which tells the device how the color actually looks, and how to make it look the way it should.

It works this way; your camera captures and stores images, which exist in the natural color space of the camera, determined by its sensor and imaging engine. But your computer, and the application you plan on using to view or post-process your images, know nothing of these characteristics. So, when you import the images from your camera the computer doesn’t now how to make them look. So, they all have a color cast (let’s say blue), and they’re all a bit flat (have low contrast). Enter color management.

Most cameras export images to a standard color space, which can be interpreted by the computer. So, the job of the profile is to apply a curve that counteracts the blue cast, and restores the correct level of contrast. Use the correct profile, and the image looks as it should. Use the incorrect profile, and things begin to go horribly wrong. Use no profile, and you take your chances either way.

The Input Color Space
So, which profile should you be using? Naturally, there isn’t a straightforward answer to this question. But for now, let’s just say that practically all modern consumer capture devices (which includes not only cameras but scanners as well) export the images to the sRGB color space. sRGB IEC61966-2.1 to be exact. So, it’s likely that you’re already using this color space. No problem there.

The problem comes comes when you import the images to your computer, but it does’t know that they’re the the sRGB color space because the images were not tagged as such. And I’ll pass along a little story to explain this.

A few years ago, I had a color management epidemic, whereby most of the color was being kicked back by our clients for the same reason; the skintones were far too red, and the shadow detail far too dark. As it turned out, clients were supplying us with digital images which were untagged, meaning information regarding in which color space the image was exported was not included in the image file. So, when the images were first opened, Photoshop asked that an appropriate color profile be chosen. Naturally, having learned a little about digital color along the way, most of my colleagues chose Adobe RGB (1998), the superior color space.

A little knowledge can be a dangerous thing.

The fact is, Adobe RGB (1998) is a superior color space. It’s color gamut (the range of colors it can store) represents both what the eye can see, and what can be printed using the CMYK four-color process. Sadly, sRGB falls a little short. But, speaking English does’t help you when others understand only French. If you don’t speak the native tongue, you can’t interpret the information correctly.

The other, less common half of the epidemic was that the color was kicked back for being “flat and dirty”. Flat, meaning too little contrast, and dirty meaning that the fleshtones leaned toward cyan, the compliment of red. As it turned out, this is exactly what happens when you assign the wrong ICC color profile to an image.

So all this translated to two scenarios:

sRGB images which were not tagged sRGB were being interpreted in Adobe RGB (1998) color space, forcing them to gain contrast and shift to red.

Adobe RGB (1998) images (far less common) which were not tagged Adobe RGB (1998) were being interpreted in the sRGB color space, forcing them to lose contrast and shift toward cyan.

No one likes little green people, so even without the knowledge that Adobe RGB (1998) is a superior color space, folks tend to prefer the warmer look of Adobe ’98. That is, until it finds it’s way onto a contract proof.

The biggest problem in color management is the fact that you can easily assign a different profile to an image than the actual color space in which it exists, or, not assign one at all, leaving everyone guessing. And if the latter is the case, it takes a very experienced professional to know which is the correct profile to assign. Therefore, unless the image comes from a reliable source, never trust an embedded profile.

The Output Color Space
Incorrectly assigned profiles are easily corrected by simply assigning and embedding the correct profile, because assigning a profile (tagging an image file) is non-destructive (does not permanently affect image pixel values).

However, the real problem happens once the image is converted to another color space, such as the working space or the output space, which makes the interpreted color more or less permanent, or at the very least not easily undoable. So, you don’t want to archive your images in the output space, because it may change depending on the service provider or destination media. If the initial color space is interpreted correctly, you can freely convert from one color space to another, including L*a*b*, RGB’s close cousin.

Therefore, sRGB is the most common RGB output space, since it’s the native color space of computer displays, consumer photo printers, commercial photo printers, and the web, all of which are output destinations.

The other type of output profile would be for commercial printing, which most likely will be a CMYK output profile such U.S. Web Coated (SWOP) v2.

When an RGB image is converted to CMYK, it becomes a 48-bit image, each of the four channels containing 8 bits of grayscale information. The gray component of the three RGB additive primaries (colors which are neutral and dark) are removed from each of the RGB channels, and combined into the black channel. Each of these channels is then inverted to reflect the change from an additive (transmissive) color space to a subtractive (reflective) color space. The specifics of these conversions are very different depending on the press profile. Therefore, converting to a CMYK space is not reversible.


The Working Space
This is an intermediate color space that you use to work in, and the intended purpose for Adobe RGB 1998. The reason to convert to (NOT assign) a working space is to expand the color gamut to allow enough room for the enhancements you are likely to make during post-processing. For example, in the process of adding saturation, you’ll be changing the values of the existing pixels to brighter colors than can be stored in the sRGB space. Since the working space is the space you are going to archive your images in, you will always have all the information you’ll need for the best possible conversion to the output space, be it now or in the future.

Many new cameras include the ability to store images in the Adobe space, which works equally well as both a capture and working space. This has the advantage of simplifying workflow, since only one conversion to the output space is required.

One the other hand, if you do not intend on doing any post-processing or are planning on printing directly from your camera or memory card, sRGB is probably the best choice. Most commercial photo printers work with this color space exclusively, so if you hand them a card with Adobe 98 images, they'll come back red and contrasty.

ProPhoto is a color space designed with the professional photographer in mind. It’s large gamut is designed to store every concievable color from the widest variety of capture sources. It’s an excellent space in which to process and archive images, but conversion to an output space is an absolute must.

Color Gamut vs. Bit Depth
The other caveat to working space is bit depth, or the amount of tonal information stored in the original file. A standard “24-bit” RGB image file has 8 bits per channel for a total of 256 levels of tonality. A 48-bit CMYK image has the same number of levels, it just has an extra channel for black.

But a 16-bit file has 65,536 levels of gray. It is said that a print can only store about 100 levels. The question is, which 100 of the 65,536 will you choose? In other words. If you have a grossly underexposed digital image with 65,536 levels of information, lightening the image to fit those 100 on a paper print with no degradation of image quality is a snap.

The downside to a 16-bit working space is that it takes up a lot of space when archiving, so use it for only the most worthwhile images. Also, many Photoshop filters will not work with 16-bit images.

Summary
That’s a lot to digest, so here’s a quick summary for reference:

Use the sRGB color space when:
Capturing images that are to be printed directly from the camera or memory card.

Converting images for use on the web, or being handed off to a commercial photo printer.

Use the Adobe RGB (1998) color space when:
Capturing images that will be post-processed and archived with layers intact.

Converting images from sRGB that will be post-processed and archived with layers intact.

Use the ProPhoto RGB color space when:
Converting images from any capture color space that will be post-processed and archived with layers intact.

Use 16-bit color when:
Converting 12 or 14-bit Camera Raw images that will be heavily post-processed such as extreme exposure adjustments.

Working with high-quality grayscale images.

Converting images from any color space that will have gradients added to them in Photoshop.