Review: Minolta MD 50mm f/1.7

Minolta MD 50mm f/1.7

This is an equipment review of a somewhat different nature.
I purchased this lens for my SR-T201 body for the purposes of both display and shooting, since I “acquired” this camera with a ROKKOR-X 100mm macro lens. It’s a considerably newer lens that this body, and its build quality is along the lines of the Nikon E-Series, in that the focus and aperture ring are made of plastic. However, also similar to the E-Series, it has great optical properties. It fits perfectly on the SR-T201, goes with the camera quite nicely and was very inexpensive.

But now that I have the Fotodiox MD-Nikon Lens Mount Adapter, I decided to see how it performs on the Nikon D90. With the Fotodiox adapters for Nikon, it’s possible to remove its optical elements, thus restoring the original optical performance of the lens at the expense of infinity focus. Used as is, these corrective optics increase the focal length by a factor of 1.4x, making this a 105mm lens (50mm x 1.5 x 1.4). Removing the optics has the effect of converting the lens to a 75mm macro with the mount adapter acting as a 10mm extension tube. So, I decided to test it both ways.

With the optical elements in place infinity focus is indeed achievable, but the optical quality suffers somewhat at larger apertures. As expected, the image gets softer in the corners, but maintains a fairly high level of center sharpness. But this is at f/5.6. At f/1.7, the results are very different. The image is actually quite sharp, but it’s veiled by coma. So much so, that the image looks as though it was shot through a fog filter. But more on that later.

At f/2.8 the condition improves considerably, giving a pleasant soft focus portrait effect similar to using a diffuser. By f/4 it’s practically gone. f/5.6 yields some pleasing images indeed, and f/8 and f/11 are quite sharp, even at the borders and extreme corners. Shot at its optimum apertures of f/5.6 to f/8.0 it would be difficult to tell these images apart from those of a native lens.

The minimum focus of the lens is approximately 1.5', and with the adapter the focal length increases to about 70mm (105mm on an APS-C DSLR). These are ideal qualities for a close up or portrait lens.

With the optical elements removed the minimum focus distance changes to about 5.5", giving the lens macro properties. It also increases the speed by about a stop. However, infinity focus can now only be achieved at about 8.5", so this is now definitely a macro lens not suitable for close up work. And as you might guess, it works very well with extension tubes which increase the magnification further without degrading image quality.

At this point you can see the true nature of this lens; wide open it’s tack sharp in the center, and indeed softer in the corners, but the norm for a lens in this price class.

The Verdict
Converted for use on Nikon APS-C DSLR bodies with the Fotodiox MD-Nikon lens mount adapter, this lens makes a fine 75mm macro lens, and an excellent 105mm soft-focus portrait/closeup lens.

As a portrait lens, the focal length is quite flattering, and under controlled lighting the degree of softness can be controlled by the aperture setting. Stopped down, images are quite sharp. Used wide open, possibly with an ND filter under brighter conditions, images have a diffused quality similar to that achieved with a diffuser or fog filter. If this is the desired effect, this lens can produce very unique effects, and I might easily reach for this lens/adapter combo rather than use such a filter.

As a macro lens with the adapter’s optical elements removed, this lens is considerably sharper at f/1.7 than the AF-S NIKKOR 50mm f/1.4 with a 12mm extension tube shot at f/1.8. In this case the adapter behaves like a 10mm extension tube, and the resulting image quality should be exactly as it would if used on a Minolta body with a 10mm extension tube. (Taking into account how the Nikon’s sensor responds to the projection from the Minolta lens.)

The whole point of swapping lenses in this manner has become clearer to me; it's not ultimately about image quality, it’s about optical effect. The combination of the lens and Fotodiox lens adapter’s optics can yield subtle to dramatic effects that are worthwhile pursuing in the interest of creative photography not unlike the Lensbaby of which I am a big fan.

Build Quality ★★★★

Similar to the Nikon E-Series, this lens has a plastic focus and aperture ring. However the quality of the molding makes it difficult to distinguish them from the metal components which make up the body, mount and filter threads. Engraved, paint-filled markings give it a quality appearance. At only 5.8 oz (166g) and 1.44" long (3.65cm) it’s very compact and lightweight.

Compatibility ★★★★

Will fit any Minolta SR-mount body, providing coupled auto aperture. Will fit any Nikon body through the use of the Fododiox MD-Nikon or similar lens mount adapter with some loss of image quality and an increased focal length. This adapter does not provide aperture coupling and so is suitable for manual (all models) or aperture priority (some models) shooting only. Metering may not be available on consumer grade bodies. In this case, for digital use the histogram and for film use an external meter such as the Gossen DigiSix.

Focusing ★★★★★

Buttery-smooth and perfectly damped. 180° from minimum focus to infinity. Full hyperfocal scale from f/4 to f/22 and infrared focus index are included.

Optical Quality ★★★

Tested on the Nikon D90 with the Fotodiox MD-Nikon Lens Mount Adapter, images were surprisingly sharp at f/5.6, falling off somewhat at the borders and extreme corners. Wide open, the images were quite soft, but with a pleasing, veiled soft-focus quality. At f/8 and above, images were very sharp, and all apertures exhibited excellent color rendition and contrast. The bokeh was somewhat agitated, with the diaphragm blades clearly visible in specular highlights.

Value ★★★★★

As with the Nikon E-Series, these lenses offered excellent optical quality at an affordable price. On the second market, they are a steal.

Diaphragm

6 curved blades, f/1.7-f/22, with half-stop increments between f/2.8 and f/16.

Filters

Accepts 49mm filters in its metal, non-rotating filter threads. The Hoya Pro1 Digital MC UV(0) is highly recommended.

Hood

A groove around the outside of the filter threads indicates a snap-on hood, but if you can’t find one, the Hoya 52mm Screw-in Rubber Zoom Lens Hood is an excellent replacement.

Sample Images
Other than a slight sharpening before resampling them to 50% of their original size, these images have come straight from the camera with no further post-processing.