The problem with filters is that anything you place in front of the lens is technically going to degrade your images, even though the filter’s goal is to enhance them. If the glass isn’t pure, the color and clarity will be affected. If the glass isn’t perfectly flat, distortion will occur. If the glass isn’t coated, less light will be transmitted and that which does will bounce back and forth between the lens and the filter causing flare and ghosts. So a filter is by necessity a precise optical device. While the surface is not curved like a lens, it must by perfectly flat, so it still requires lens-like precision in its manufacture.
That said, filters are often more expensive than they need to be, and it’s easy to get caught up in the filter game. Filters generally come in three grades; uncoated, single-coated and multi-coated, however some special filters like diffusers may not be available with any coatings, and ultra-high-end filters may have features above and beyond mere coatings. It’s easy to over-purchase, putting you well past the point of diminishing returns.
It’s easy to under-purchase as well. Many brands such as Cokin don’t specify whether their filters are uncoated or single-coated, although they generally indicate if they’re multi-coated with the designation “MC”.
Filters by Brand
One of the best values in filters today are the Hoya standard or single-coated filters. With the exception of diffusers and other special effects filters, all are single coated on both sides of the glass, and are very well constructed. Hoya’s multicoated filters are outstanding, and for a filter you use all the time, such as a UV, NC or Skylight, the added cost is well worth every penny. Hoya filters are made primarily in Japan, with some of the more common types made in the Philippines.
Tiffen’s standard line is by far the least expensive, but they’re not even single-coated, and constructed of laminated glass which is often criticised. Still they are indispensable for situations where frequent cleaning may be necessary. Tiffen also offers a high-end multicoated line, but nothing in between. Tiffen filters are made in the USA.
B+W and Heliopan filters from Germany use arguably better Schott glass, and their frames are constructed of brass, which may hold up better to repeated use. Like Hoya they offer single and multicoated versions of most filters. Without question they’re the best filters you can buy, but carry a premium price and may not offer you as high a return on investment as the Hoya and Tiffen. B+W’s F-Pro series use slightly thinner frames (approximately 1mm) than the Hoya, but etch the filter’s designation on the front rather than the side, making it impossible to read if mounted in at the bottom or middle of a stack—a minor quirk.
Cokin Filters are from France, and come in two designs; screw-in and frameless rectangular resin. With the exception of the multicoated UV and Skylight filters, the screw-in filters do not specify whether they are coated or not. The resin filters, although of high quality, are definitely uncoated and susceptible to scratching. They are however, inexpensive by design and great for less precise, creative applications. The Cokin creative system was designed from the ground up to be economical by offering four different sizes of rectangular filters and holders, and inexpensive adapter rings to adapt them to different sizes of lenses. Cokin also has a unique mounting solution for compact cameras without filter threads.
Avoid bargain or off-brand filters or filter sets which typically contain a polarizer, UV and ND filter with case for the price of a single premium filter. The filters included in these set are not the same as individual filters, and will do you no good if they degrade the image.
A popular trend in filters is to offer specialized lines such as “Digital Coatings” or “High Density Glass”. Just like in digital audio, digital coatings are simply a higher quality to meet exacting demands. Buy them for their quality and features, not because they’re labeled digital. High Density glass is designed to avoid breakage, so invest in these only if you plan on using them under adverse conditions.
Digital In-Camera Filters
Many cameras have digital filters built-in, such as yellow, orange, red and green for black and white images, and for color images custom white balance settings. However, these modify the light after it strikes the sensor and while achieving a similar effect, can never fully duplicate the effects of a good optical filter.
These are some things to consider:
- Aluminum Anodized frames are the most common, and hold up well under normal use. Many come in thin or ultra-thin designs to avoid vignetting on wider lenses. The ultra-thin designs do away with the front threads so stacking filters on top of these is not possible.
- Brass Frames are the most durable, and harken back to the early days of photography where many camera components were made of brass.
- Laminated Glass or “Color Core” technology which is used in Tiffen filters uses two pieces of thin glass with a colored layer in between. It’s possible for separation between the layers to occur, and because of the core they cannot be heated to the temperatures required for coating. However, more precise color control during manufacture may be possible.
- Solid Glass has the color running all the way through, and can easily be single or multi-coated.
- High-Density Glass is a new technology that has approximately four times the tensile strength of regular glass. So, if you frequently drop your filters on concrete, they will be protected.
- Uncoated Glass is easy to clean and relatively scratch-free. It’s ideal for use near the seashore or under misty conditions.
- Single-Coated Glass transmits more light and suppresses flare and ghosts. Ideal for most filters, especially if using lenses with high-quality coatings. More difficult to clean, coatings are susceptible to scratching.
- Multi-Coated Glass virtually eliminates flare, ghosts and light loss. Great for everyday filters such as UV, Skylight or NC (clear), or for any application where you plan on shooting into the light, or using with an uncoated lens. Again, more difficult to clean and susceptible to scratching.
- Ultra-Hard Coatings are final coatings such as titanium which protect the optical coating and make cleaning easier.
Protection Filters (essential for digital or film)
Although you may store your lenses without filters, you should never use them without a filter to protect the lens from damage and reduce the need for cleaning. Each time you clean a lens, you take the chance of scratching it, and exposure to the elements will eventually take their toll. There are three types of protection filters, some which enhance the image and some which have little or no effect. A high quality, coated filter will produce little or no optical degradation, while a lesser quality, uncoated filter may introduce flare and ghosts.
- NC (Neutral Contrast) Filters are essentially clear filters for the sole purpose of protecting the lens without affecting image quality. However, lesser quality, uncoated filters may actually degrade the image.
- Skylight Filters are very subtle warming filters which help to counteract the bluish cast from UV rays present in skies and flash. It also helps to warm up fleshtones, although very subtly. It always imposes a color shift.
- UV Filters are actually bandpass filters which to some degree block the blue-colored Ultraviolet component of the spectrum. In theory, they only take effect if UV rays are present, so they remain neutral until needed. This is the best combination of the three, however many UV filters are simply not effective, so be sure to read test results first. There is a simple test you can perform yourself using a black light.
Polarizers (essential for digital or film)
Color saturation and contrast can be greatly enhanced with a polarizer, which cancels out light rays in a given plane which is determined by the rotation of the filter. They can also reduce distracting reflections in water, glass and other surfaces.
- Circular Polarizers are designed to work with both the newer autofocus and older manual focus cameras.
- Linear Polarizers are designed to work only with older manual focus cameras as they may interfere with the autofocus system.
- Warming Polarizers incorporate a warming filter to eliminate the need to use two filters together. (Not essential for digital, as the camera’s white balance can be used to warm the image when used with a polarizer).
- HRT Polarizers use a High Transmission Rate film to reduce the amount of light they block.
Neutral Density (essential for digital or film)
For times when you exceed the limits of your camera, the ND filter can provide the equivalent of a smaller aperture or lower ISO. This is necessary to achieve special effects, such as reduced depth of field or long exposure times in bright light. Graduated ND filters allow you to extend the dynamic range of your image by reducing exposure in selected areas of the image.
- Standard ND Filters come in different densities. An ND2 (filter factor .3) reduces the light 2x or one stop, an ND4 (filter factor .6) reduces the light 4x or 2 stops, an ND8 (filter factor .9) reduces the light 8x or 3 stops, and an ND16 (filter factor 1.2) reduces the light 16x or 4 stops. There’s also an ND400 which reduces the light by 9 stops for astronomical or time exposure applications.
- Graduated ND Filters are typically available as ND4 on one side, and clear on the other with varying degrees of transition in between.
Special Effects (used for film, optional for digital)
This category includes diffusers, soft focus, soft spot, star filters and others. Many of these effects can be achieved in post-production, but often the optical effect is superior. Diffusers, Soft Focus and Duto filters are particularly useful for portraiture.
- Diffuser/Soft Focus Filters use a coating to modify the surface of the glass, creating irregularities which create a softening or contrast-reducing effect.
- Duto Filters use a series of concentric circles etched into the surface of the glass to create a softer focus around the edge of the image, with a sharper area in the center.
- Soft Spot Filters are diffusers or close-up lenses with clear centers to allow more pronounced softening of the edges with an even sharper center than a Duto.
- Star Filters use diagonal lines etched into the surface of the glass to create four, six or eight-pointed stars wherever a point of light occurs in the image.
- Multi-Image Filters use a series of prisms to create multiple images similar to a Kaleidoscope.
Color Conversion (used for film, unnecessary for digital)
The ability to adjust white balance digitally has made color conversion filters obsolete for digital cameras, although the 81 and 82 series may still be useful as warming or cooling filters.
- 80A, 80B, 80C Filters are used to convert daylight film to various tungsten lighting sources.
- 85A, 85B, 85C Filters are used to convert various types of tungsten balanced film to daylight.
- 82A, 82B, 82C Filters are cooling filters.
- 81A, 81B, 81C Filters are warming filters.
- FL-D, FL-B, FL-W Filters are used to balance daylight film to various fluorescent lighting sources.
B&W Conversion (used for film, optional for digital)
Many digital cameras have the ability to enhance black and white images directly in the camera using red, green and yellow digital filters, making optical filters unnecessary. However, these filters may also have other creative applications.
- Red (25A) deepens skies and enhances contrast. Also for use with infrared film.
- Orange (G) increases contrast between reds and yellows; in color photography can be used to enhance sunsets or simulate a redscale film effect.
- Yellow (K2) separates sky from clouds and foreground.
- Yellow-Green (X0) enhances skintone in outdoor portraits.
- Green (X1) enhances skintone in indoor portraits.
Didymium Filters (used for digital or film)
These filters do not use colored glass, but rather rare-earth minerals added during the manufacture of the glass to filter out certain colors in the visible spectrum.
- Intensifiers are a relatively strong filter used to enhance autumn foliage.
- Portrait Filters are a milder filter used to warm fleshtones without affecting other colors or creating color casts.
Infrared Tranmission (used for digital or film)
These filters suppress most or all visible light and allow only infrared rays to pass. They are used with digital or film to produce color or black and white infrared photographs. There are basically four classes of IR filter, listed in their order of sensitivity:
- #25, #29 (Red) are very popular filters used in black and white photography and are an excellent foray into infrared photography. When used with black and white film, effects similar to IR photography such as deep skies and high contrast in foliage can be achieved. When used with infrared films, true IR effects can be achieved. #25 suppresses wavelengths below 580nm and #29 below 600nm. B+W, Cokin, Formatt, Heliopan, Hoya and Tiffen all manufacture #25 filters, while #29 is available from B+W, Formatt and Tiffen.
- #70, #89B (Dark Red) is the second most usable filter in this class, as it suppresses most visible light, but allows a small portion of the upper red bandwidth to pass, beginning at about 650nm. This can be helpful for cameras which are less sensitive to IR, or to achieve different effects by allowing visible light to interact with infrared light. The B+W 092M is an excellent choice.
- #88A is the most usable filter in this class, as it suppresses all visible light, yet passes infrared radiation as low as 720nm, just beyond the visible range. This allows it to work with most digital cameras, even if they have not been converted. Newer cameras might require longer exposure times. The Hoya R72 and RM72 are coated glass versions, while the Singh-Ray I-Ray is a resin version.
- #87, #87C, #87B are ideal for use with cameras that are very sensitive to IR or that have been converted by removing their hot mirror filters. It begins to pass IR at 800nm, well into the infrared range, and peaks at around 900nm. Look for the Tiffen #87, B+W 093 and the Hoya RM90.
Strategizing your purchases
Assembling a collection of useful filters for all your lenses can be a daunting and expensive task. Unless all your lenses are the same size, you may find yourself purchasing duplicates of the same filter in different sizes. You may restrict filters to certain lenses initially, only to find you need them for other lenses anyway.
A good approach is to buy a high quality UV filter for each of your lenses; if you have two lenses that are the same size, consider purchasing a skylight or NC filter for the second lens.
Then, of the lenses you will be using most often, determine the largest filter size, and purchase all of your additional filters in that size, using step up rings to adapt them to smaller lenses. For example, if you have 52mm, 58mm, 62mm, and 67mm lenses, and a 72mm lens that you don’t plan on using that often, purchase 67mm filters with the appropriate step-up rings. If the 72mm lens is a longer focal length, you might be able to use a 67mm filter with a step-down ring without vignetting.
Recommendations
Hoya Pro1 Digital MC UV(0)
I personally use one of these on each of my lenses for protection as standard equipment. Their coatings are excellent for both film and digital, they are completely neutral until needed, and their ring design makes them easier to remove if they get stuck. They are one of the only UV filters that’s actually effective in suppressing UV radiation as revealed in test reports and confirmed by my black light test.
Hoya UV(0) Japan
If you can still find them, this filter offers a level of UV suppression equivalent to the Hoya Pro1 Digital MC UV(0) at a much lower price. However, the latest multicoated version which is made in the Philippines does not offer the same level of performance, as confirmed by the black light test.
Nikon Circular Polarizer II
This multicoated filter is on a par with the Hoya Pro1 Digital series. It’s no thicker than a standard filter, but features a knurled design that makes it easy to install and remove. Most importantly, it transmits about one third-stop more light than a standard polarizer.
Tiffen Haze-2A
This uncoated filter offers industrial-strength UV filtering at a price; it imposes a very slight yellowish cast at all times, but has a degree of effectiveness even greater than the Hoya UV(0). Great for use at high altitudes or near the ocean, where UV suppression requirements are the greatest, and environmental conditions are harsh.
Tiffen Skylight 1-A
This was my first filter ever, and it’s never let me down. The most inexpensive, easiest to clean filter with mild warming capabilities.
Tiffen Warm Low Light Polarizer
A good compromise between a polarizer and a skylight filter. Milder polarization with only one stop of light loss, combined with the warming effect of a Tiffen 812 filter. Can be used as is, or as a neutral low light polarizer by performing a custom white balance through the filter. This filter is quite inexpensive and may prove to be a good “protection” filter for everyday use.
No comments:
Post a Comment