Review: Minolta RF Rokkor 250 mm f/5.6 (MD-II)


The RF Rokkor 250 mm f/5.6 is one of the most sought after lenses in the Minolta SR system. Though it was produced in not-so-small quantities, used prices for this lens today are through the roof. This is often attributed to it’s astonishing compactness, which renders it the “perfect compact tele on a NEX”. But this aspect does not seem sufficient to single-handedly explain the hype.

Handling on a NEX-5T is a pleasure, with the only  notable insight being that the lens is very light. Focusing presents a challenge with the RF, as the depth of field is extremely shallow and the 9.6x focus magnification on the NEX shakes wildly when used without a tripod.

For the RF Rokkor 250 mm f/5.6 I’ve created lens correction profiles, which are available for download. 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: Very good. No visible scratches whatsoever. A handful of lonely dust particles and a slight shimmer on the inside of the front glass, probably from condensation.

Mechanics: Excellent. Smooth focus, filters (Skylight & ND 4x) in perfect condition.

Exterior: Excellent. Looks like new, except for minimal scratches on the mount.

 

Optical performance on NEX-5N / 5T

Since the RF Rokkor is a mirror lens, there is only one aperture of f/5.6 which is given by the front opening. Sharpness is not impressive, but good for a medium tele and very consistent across the frame. Contrast is equally good and chromatic aberrations are non-existent – even at 200% magnification. This is attributable to the fact that mirrors do not have a wavelength dependent refraction index and therefore do not produce CAs.

Vignetting is about 2/3 of a stop, distortion is low with 0.5% pincushion. The effective T-stop of the RF Rokkor is approximately T7.2 (-0.7 EV), which is not bad, considering that the center of the entrance pupil is obstucted by the secondary mirror.

Compared to the often praised MD Tele Rokkor 200 mm f/4 @ f/5.6, the RF Rokkor performs respectably. The RF looses by a notch in terms of contrast and sharpness, while it clearly outperforms the 200 mm in terms of CA.

 

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/5.6

RF Rokkor 250 mm f/5.6 @ f/5.6

 


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2 thoughts on “Review: Minolta RF Rokkor 250 mm f/5.6 (MD-II)

  • Barabas

    I got shocked when looking at old adds; during the mid-80s the 250mm f5.6 was sold for less then the 200mm f4. The 200mm f4, which is one of Minolta’s very best non-apo telelenses, is outperforming the 250mm in many aspects, so I guess that is why the 250mm was sold for the same or lower price in the end.

    Why some people are nowadays willing to pay over 10 times more for the 250mm is a mistery to me, it might be gear aquisition syndrome. It isn’t that sharp, it has a fixed aperture, it has vignetting, you get ‘donut’ shape bokeh; all sacrifices made for compactness. I’m sure dealers won’t mind about the hype, but why not use the money to get the 200mm f4 plus a few other (really) great Minolta lenses instead?

    • Benjamin Post author

      There’s been quite some discussion about this on the net (for example: http://photo.net/modern-film-cameras-forum/00Y7W8). Nobody really knows, why the RF 250 is that expensive nowadays. The most probable explanation is that the µ4/3 and APS-C E-mount users have driven the prices up while looking for a compact and light tele lens. The fact that no such native lens was available for these systems at first could have played a role, too. What I still find odd is, that most of the RF’s seem to be sold to Hong Kong and Japan…

      Regards,
      Benjamin