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

120-140mm


120mm

At f/2.8 the Carl Zeiss Jena MC Biometar produces a very satisfactory image across the whole of the frame, for the plane focussed on. The shop signs look sharp, although the loupe does reveal a slight lack of resolving power for some very small details (e.g., the cream-coloured sign on the Tea & Coffee House sign).  At f/11 this has sharpened up so that with a loupe I can read the lettering on this sign.  Likewise, the roof tiles have sharpened up across the frame.  At this aperture, the 120mm Biometar is as sharp and contrasty asif not sharper thanthe best of the 80mm lenses at f/11but then one would expect to see more detail, as the view is magnified 50% more than with the standard lens.


[C297-3: 120mm Biometar at f/11, 1/125]

Since completing the test I have purchased the Arsenal Vega 120mm f/2.8 lens. This has yet to be tested, although I have taken “mug shots” of it. This is what it looks like:


[C306-31: The 120mm Arsenal Vega lens (l) and the 120mm Carl Zeiss Jena Biometar (r), each with its lens hood fitted.]

This lens has a fractionally longer focal length than the 120mm Biometar, i.e., it covers a fractionally narrower field of view.  However, physically, it is hardly larger than the Volna standard lens:


[C306-29: The Arsenal Vega 120mm lens, in the middle, compared with the Arsenal 80mm Volna standard lens, on the left, and the Carl Zeiss Jena 120mm Biometar on the right.]

However, unfortunately, it is not possible to close the Pentacon Six “ever-ready” case with the Vega fitted to the camera.

Rick Denney reports that “The 120mm Vega is nice and sharp, but not really any cheaper than the 120mm Zeiss Jena MC Biometar.”  Rick has made a detailed comparative study of the rendering of out-of-focus components of images using these two and some other lenses.  The technical term for the (deliberately) out-of-focus part of an image is “Bokeh”.  The results of Rick’s study can be found at http://www.rickdenney.com/bokeh_test.htm .

140mm

A further slight magnification of the view is afforded by the 140-280mm Schneider Variogon at its 140mm setting.  Even though its maximum aperture is f/5.6, this is a very large lens.  At f/5.6 the results are outstanding, both in terms of sharpness across the whole frame and contrast.  There is a further increase in sharpness (and marginally in contrast) at f/11, but to see it you’d need a powerful loupe or images much larger than my 8 × 8 prints.  The lens certainly deserves its outstanding reputation, and it is clear why Hasselblad users for decades have been happy with the images it produces.


[C303-4: 140-280mm Variogon at 140mm and its maximum aperture of f/5.6!  The shallow depth of field means that the front cobblestones are out of focus, but this is not due to a poor lens definition, merely a consequence of using a longer focal length lens.]

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© TRA January 2002, November 2008