Medium Format Lenses with the Pentacon Six Mount
A comparative test
by TRA

The wide angle lenses (2)
40-50mm
 


[C373-0A] The wide-angle lenses, from L to R: 40mm Distagon, 50mm Flektogon, 40mm Curtagon,
65mm Flektogon, 45mm Mir 26, 65mm Mir, 60mm Curtagon

The following wide-angle lenses were included in the original test:

plus, for comparison purposes, the 40mm f/4 Carl Zeiss Oberkochen Distagon in Hasselblad mount.

Since the original tests, most of which were completed in 2001, I have been able to add four key wide-angle lenses to my outfit:

Results of tests with these lenses are now included, although I was not able to return to Hitchin town square to shoot comparative shots.

The 40mm Curtagon lens can best be described as “extremely rare”.  To read the story of this lens click here.


[C373-4A: the wide-angle lenses, together with the 30mm Zodiak, with lens hoods attached]

The results

40mm

The 40mm f/4 Carl Zeiss Oberkochen Distagon lens fully deserves its high reputation. At its maximum aperture the depth of field is relatively shallow, even for this wide-angle lens, and the cobblestones of the road surface near to the camera are out of focus. However, in this shot a banner at the very edge of the shot within the plane of focus is beautifully sharp. At f/11 the increased depth of field renders the whole image sharp into the corners.


[C299-5: 40mm Distagon at f/11]

To read a review by me of the rare 40mm Joseph Schneider Curtagon lens click here.

45mm: the Mir-26B

This is the Ukrainian 45mm lens that you are most likely to find available for sale.  At the maximum aperture of f/3.5, the Mir-26B produced an image that was only sharp in the very centre. This is not just the effects of depth of field. The shop sign “Visions”, about one third in from the left and exactly half way down the frame, is quite fuzzy. At f/11 we benefit not only from increased depth of field; the whole image sharpens up tremendously.


[C303-3: 45mm Mir-26B at f/11]

This lens suffers from slight barrel distortion at the edges.  In many shots – including this one – that distortion is not noticeable, but sometimes it can be seen, as in the following two images.
 

[C344-6: 45mm Mir 26B 1/250 f/11 focussed at hyperfocal distance Kodak Portra 160 ISO Pfänder, Austria
I’m sure that bench didn’t sag in the middle.

[C237-4] Mir 26B 1/30 f/6.3 Fuji 400 ISO film
The ceiling beam and the floor tiles definitely were straight (though I think that the door next to the dishwasher was either crooked or not properly shut).
[C345-1]  Pfänderspitze, Austria. 1/250 f/19 Fuji NPH 400

From a compositional point of view, this shot needs cropping, but I am including the entire frame here to show that with the 45mm Mir lens there is a total absence of vignetting – often a problem with wide angle lenses.  In this image the slight barrel distortion produced by this lens is also not noticeable.

 
Sample Variation

It is frequently stated that the optical design of Soviet lenses is good; it is the manufacturing or the quality control that is bad.

I hope that the results of tests reported on this website give some indication of how far the optical design is good or not good.  If a lens has significant, clearly visible barrel distortion, that is not good.  The same applies to chromatic aberrations (colour fringeing) and other defects with a few lenses that are described elsewhere on this website.

As regards poor manufacturing tolerances or poor quality control, I received in July 2011 the following report from website visitor Lionel in Canada:
I've been amazed by your pictures taken with the Mir lens, especially with the Mir-26. I had the same issue with this lens, bad sharpness at infinity, which is also reported on the Kievaholic web site. Whereas the Mother of the Lens test page reported great results. My Arsat 80 is also not top notch.
I've tried the lens on film, with a Kiev 60 and on a Pentacon Six.  I have even tried with a DSLR. And I've checked everything: mirror placement, focusing screen adjustment ... And finally after dismantling the lens trying to figure out why on two Mir-26 lenses and on the Arsat. I've found two major problems [with the Mir 26]:
- screw length of the Mir-26 aperture tab varies and the tab itself is not plane.
- the spacer between the lens mount and the focus unit can vary by 0.5-1 mm between my two Mir-26 lenses.
After quite a [lot of] work this winter, I obtain sharp results, even wide open, with my Mir-26 lenses.

Lionel wisely first checked other possible sources of problems (in the cameras), but in his experience it was not his cameras that were faulty but the lenses were.  By adjusting his lenses in a way that should have been done in the factory! he has obtained sharp results with the Mir-26.  Readers with lenses that appear cosmetically and mechanically in good condition - but that deliver poor results - may wish to send their lens to a lens specialist such as Tom Page in England or Peter Olbrich in Germany.  And such specialists may be able to improve the lens substantially - although this cannot be guaranteed, as it depends on what they find when they open the lens up - and they do not usually have spare parts for these lenses!

45mm: the Mir-69B

This extremely rare Ukrainian lens was apparently produced in tiny quantities in 1989.  According to some sources, probably less than 20 examples of this lens were produced.  The price of the lens when found therefore reflects this scarcity.  However, what is this lens like, and what is the quality of the images that it produces?

Technical specifications of this lens can no longer be found, so unless one strips a lens down, it is impossible to be sure how many elements and groups it contains.  According to one rumour, it “contains more elements than the 30mm Zodiak fish-eye lens”.  Most data published by Arsenal in the 1980s does not specify the numbers of elements and groups in lenses.  However, according to one report this lens contains 9 elements in 7 groups (one element more than the Mir-26).  The same report states that its resolving power is also better than that of the Mir-26: 55 line pairs per mm at the centre and 21 lp/mm in the corners, compared with 45 lp/mm in the centre and 16 lp/mm in the corners for the Mir-26.  This is a clear improvement on the more common lens.

Here is the Mir-69, placed beside the Mir-26 to give a clear size comparison:


The two Ukrainian 45mm lenses: the more common Mir-26B on the left, and the rare Mir-69B on the right

The Mir-69 45mm seems to have exactly the same angle of view as the Mir 26B 45mm (as should be the case!).  It is virtually identical in size to the Vega 28B 120mm lens, which means that the front of the Pentacon Six case won’t quite close with it on the camera, but it is massively smaller than the 26B, takes 67mm filters instead of the 82m filters of the 26B and is little more than two-thirds of the weight of the 26B.
 

Size comparison (2): L to R: Arsenal Mir-69 45mm lens, Carl Zeiss Jena Biometar 80mm lens and Arsenal Vega-28B 120mm lens

The Mir-69 has rubber studded grips for the focussing and aperture rings.  The aperture ring on this example is somewhat stiff, although the aperture itself snaps closed very fast and with no problems.  There is a stop-down lever in the usual place, helpful for stop-down metering on a Pentacon Six or Kiev 88 (on the Kiev 60 or 6C it is possible to use the stop-down lever on the camera body).  Closest focus is 0.5 metres, the same as the Mir 26B, and tests confirm that they are virtually identical.  The aperture ring is close to the body, with the focussing ring further forward, as is normal with most lenses (though the Mir 26B has it the other way round, with the aperture ring near the front of the lens!).

The direction of rotation of the aperture ring is the same as on the Vega 120mm lens (therefore the opposite to the Mir 26B).  The direction of rotation of the focussing ring is the opposite to the Vega 28B 120mm lens (which is the same as the Mir 26B), which just shows that they didn’t bother to standardise these things!

The more-common Mir-26B presents one problem that is described in detail above: barrel distortion.  How does the newer Mir-69B compare?  Is it better, the same, or worse?  I decided that it was time for some more kitchen shots, though I wasn’t able to cross continents to visit the kitchen illustrated above!  Here are the first results:
 

40mm Schneider Curtagon lens
Mir-69B 45mm lens
Mir-26B 45mm lens
All shots on Fuji NPH 400 film at 1/2 sec f/9.5
To see a larger version of each image, click on the image.

Well, they obviously didn’t lick the barrel distortion; it looks virtually identical on both Mir lenses.  The resolution however is excellent – one sees the grain of the film before any image deterioration is visible.  (This was of course 400 ISO film.).  Chromatic aberration has been corrected to a very high level in the new Mir-69 and is virtually non-existent.

These images show how important it can be when photographing with wide angle lenses to use a spirit-level on the camera.  Here I obviously didn’t, and as I couldn’t stand behind the camera, it was difficult to get it exactly horizontal!  Using the magnifying head or the angle finder could also have helped.
 

An ideal outfit?  Three Pentacon Sixes with (L to R): the Mir-69 45mm lens, the Biometar 80mm standard lens and the Vega-28B 120mm lens.

Perhaps (using one body only!) this could be an ideal outfit – although I would add the lightweight 250mm f/5.6 Arsat or Telear lens to bring in more distant detail.  It is a pity that the Mir-69B 45mm lens was first developed during the final days of the communist command economy of the Soviet Union.  Otherwise it might have gone into serial production and might even have replaced the much larger and heavier Mir-26B 45mm f/3.5 lens.  In my first tests, optically it looks just as good (it is probably better!), and the reduction in size and weight is of course extremely welcome.  The Mir-69B will now enter regular use by me, and I hope to report further on it in the future.

I bought this particular lens from Gevorg Vartanyan of Araxfoto, with whom it is always a pleasure to do business.  Recommended!

50mm

The 50mm Flektogon reveals a sharp, contrasty image at its maximum aperture of f/4. At f/11 there is (of course!) a further improvement in definition at the very edge of the frame, plus a slight increase in contrast, I think, but even with 8" × 8" prints the difference is not that obvious. A 7× loupe does confirm the improvement in definition. A great increase in depth of field at f/11 also brings the nearest cobblestones into sharp focus.


[C296-1/2: 50mm Flektogon at f/11]

Some people are concerned about the white dots that can be seen within the internal mount of some of the 50mm Flektogon lenses, but this contrasty image was taken with just such a lens!  The lens used for this shot can be seen here.

For information on filters for the Flektogon, see here and here.

For a review of the rarely-seen FAN-1 wide-angle converter, see here.

To go on to the next section, click below.
Wide Angle (3): 55-65mm

To go back to the beginning of the lens tests, click below and then choose the focal length that you want to read about.
Back to beginning of lens tests

Home

© TRA January 2002, Latest Revision: 17 May 2017