Review: Minolta MD 50 mm f/1.4 (MD-III)


The MD 50 mm f/1.4 with 49 mm filter thread from the early 80s is the last f/1.4 standard lens introduced in the Minolta manual focus line-up. The lens is less common than it’s slightly slower MD 50 mm f/1.7 and MD 50 mm f/2 counterparts which were packaged as kit lenses with popular cameras such as the X-700. The MD-III 50 mm f/1.4 is also less “internet famous” than – for example – the often praised MC Rokkor-PG 50 mm f/1.4. But after testing and using it for a while I have to say that I do not really know why…

The lens is compact and pleasantly light at 230 g. Focus is smooth but not buttery and overall handling on a NEX-5T is excellent. Although it is constructed of more plastic parts than preceding Minolta designs, tolerances are tight and the build quality is high. Focus peaking works fine even at f/1.4 as long as light is sufficient, which is not the case for many other fast standard primes. The effective focal length of 76 mm on APS-C cameras renders the MD f/1.4 a nice short tele prime for every day use and the occasional portrait.

For further details on the lens, have a look at its entry in the Minolta SR mount lens database.

 

Condition of my copy

Optics: Good. No scratches, minimal dust and a very slight haze on some elements, probably from condensed air moisture.

Mechanics: Excellent. Uniform and smooth focus with low to medium resistance, aperture clean and fast.

Exterior: Excellent. Some marks on the mount, otherwise like new.

 

Optical performance on NEX-5N / 5T

Notice: There was some asymmetry in the test shots with the left side being slightly softer and showing a bit more haze than the right side of the images. It is possible that this lens might show slightly better corner performance in practice than the test shots suggest.

 

The lens shows acceptable sharpness wide with some haze, minor purple fringing and pretty decent contrast. The performance is consistent across the whole frame. Sharpness slightly increases when stopping down to f/2 and the prominence of haze and fringing is reduced by about 50%. At f/2.8, haze and fringing are gone while overall sharpness improves to good and the center comes close to very good levels. At f/4, the lens certainly shows very good sharpness which every so slightly improves at f/5.6, where a score of “excellent” is appropriate. At f/8, the overall sharpness is reduced a tiny bit (-> very good), probably due to diffraction. Diffraction becomes more evident at f/11 and increases softness at f/16.

Some red and cyan glow is visible at f/1.4 and f/2 in the corners. Starting at f/2.8, the aberrations sharpen up and form very small red/cyan CAs that shrink further when stopping down. Overall, the MD-III 50 mm f/1.4 performs very good for a fast achromatic prime.

Vignetting is about half a stop at f/1.4 and gone by f/2. The lens also exhibits some pincushion distortion (0.4%). The effective T-stop at f/1.4 is approximately T1.6 (-0.4 EV), which is pretty okay for a fast prime. Field curvature is minimal, too.

Until buying this lens, I was under the impression that Minolta never manufactured any standard lens as sharp as the MC Rokkor-PG 50 mm f/1.4. It seemed like in all later lenses like the MD Rokkor 50 mm f/1.4 or even the 50 mm f/1.2, Minolta somehow sacrificed sharpness for either compactness, less CA or some other characteristic. Now I know that I was wrong. The MD-III 50 mm f/1.4 is up to the task. A side-by-side comparison shows that while the MC Rokkor-PG actually still has a minimal edge in resolution at f/2 and possibly f/2.8, the overall better (micro-)contrast of the MD-III results in images of higher perceived sharpness across all apertures. In all other characteristics (size, CAs, distortion, vignetting), the MD is equal to or better than the MC. The only thing the latter has going for itself are the mechanics: Focusing doesn’t get much smoother than on Minolta MC lenses.

In conclusion, the MD-III 50 mm f/1.4 is my new go-to optic for everyday use, replacing the MD-III 50 mm f/2. While the latter actually is slightly sharper in the center at f/2 and shows even less (read: zero) lateral chromatic aberration, it has softer corners, more vignetting and – surprise – it doesn’t have a maximum aperture of f/1.4. Considering that the MD-III f/1.4 is just 4 mm longer and slightly heavier, this lens offers the most bang for space in your bag.

 

Test charts

The following images are pixel-level crops from the test chart. They may appear scaled in your browser window. Click on them to view the crops in full size and cycle through them easily. For more info on the test setup, visit the details page.

 

Overview

Test chart overview

(Cropped areas marked in orange)

 

f/1.4

MD-III 50 mm f/1.4 @ f/1.4

 

f/2.0

MD-III 50 mm f/1.4 @ f/2.0

 

f/2.8

MD-III 50 mm f/1.4 @ f/2.8

 

f/4.0

MD 50 mm f/1.4 @ f/4.0

 

f/5.6

MD-III 50 mm f/1.4 @ f/5.6

 

f/8.0

MD-III 50 mm f/1.4 @ f/8.0

 

f/11

MD-III 50 mm f/1.4 @ f/11

 

f/16

MD-III 50 mm f/1.4 @ f/16

 

Field curvature at f/1.4

Field curvature: MD-III 50 mm f/1.4 @ f/1.4

 

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