Medium
Format Lenses with the Pentacon Six Mount
A comparative test by TRA The
wide angle lenses (2) |
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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:
The 40mm Curtagon lens can best be
described as “extremely rare”. To read the
story of this lens click here. For a review of a one-off
modification of a Zenza Bronica 40mm lens to
Pentacon Six mount, see here. 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. 45mm:
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.
45mm: Mir-69B This extremely rare Ukrainian lens was apparently produced in tiny quantities between 1989 and 1991. 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 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:
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. 50mm Flektogon at f/11 [C296_1-2.jpg] 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.
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For information on filters for the Flektogon, see
here, here
and here.
For a further test picture taken with a 50mm
Flektogon, see 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
© TRA January 2002, Latest Revision: April 2022