The MD 50 mm f/1.7 with 49 mm filter thread is the last in a long line of standard kit primes produced by Minolta for the SR mount. The lens has been produced in large numbers, is easy to come by used today and relatively inexpensive. But don’t mistake inexpensive for cheap – this little gem is still a solid performer.
The lens is pleasantly light, focus is smooth but not buttery and handling on a NEX-5T is excellent. On the plus side, at f/1.7 it is a little easier to nail focus using focus peaking than it is at f/1.4. On the minus side, you loose about half a stop of light and some smoothness in the bokeh. The effective focal length of 76 mm on APS-C cameras renders the MD f/1.7 an inconspicuous short tele prime for every day use that doesn’t break the bank.
For further details on the lens like weight and dimensions, have a look at its entry in the Minolta SR mount lens database.
Condition of my copy
Optics: Excellent. No scratches, no visible dust.
Mechanics: Very good. Uniform and smooth focus with slightly raised resistance, aperture clean and fast.
Exterior: Very good. Slight scratches in the finishing, some tiny marks on the edges.
Optical performance on NEX-5N / 5T
The lens is soft at f/1.7 with acceptable contrast and minimal haze. Sharpness and contrast increase radically at f/2.8 with the haze disappearing. The center reaches good sharpness now, but the corners stay slightly soft. Stopping down to f/4 increases sharpness to good in the corners and very good in the central region. At f/5.6 and f/8, the rating improves to excellent, with the corners reaching their peak at f/8. Diffraction starts at f/11, becomes evident at f/16 and softens up the image at f/22.
A minimal red and very dark cyan glow is visible at f/1.7 and f/2.8 in the corners. Starting at f/4, the lens shows tiny red/cyan CAs that disappear when stopped down to f/8. Overall, the MD f/1.7 is practically free of lateral CAs. An outstanding performance for an achromatic lens.
Vignetting is about 2/3 of a stop at f/1.7 and disappears by f/2.8. The lens also exhibits a very low barrel distortion of -0.3%. The effective T-stop at f/1.7 is approximately T1.8 (-0.2 EV), which is good.
Compared to the MD Rokkor 50 mm f/1.4 (MD-I), the f/1.7 MD-III shows a slightly different characteristic wide open: While the center is equally sharp, the corners show less haze, but also significantly less detail and sharpness. At f/2.8, the MD-I f/1.4 is ahead in every aspect. Stopping down further, the lenses are indistinguishable in terms of central sharpness, but the f/1.7 always shows softer corners. In all other aspects (vignetting, CAs, distortion), the two are too close to call a clear winner. All things considered, the f/1.7 is a good pick if you are on a budget or just searching for a light, no-nonsense prime to take with you wherever the wind takes you. For most other users, the f/1.4 is the lens of choice.
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