F = 137 137 / 5.6 (3.5), KOMZ. Review from the reader Radozhiva

Overview of the adapted lens F = 137 137 / 5.6 (3.5), especially for Radozhiva, prepared Eshmakov Rodion.

View of the adapted lens with the adapter kit installed for use with Canon cameras

View of the adapted lens with the adapter kit installed for use with Canon cameras

This lens was once acquired on one famous bulletin board out of curiosity; it has no markings other than the manufacturer (KOMZ), focal length and relative aperture. Also, this lens (or at least something identical to it) is not described in any of the optics directories I know. The serial number indicated on the lens block case may indicate the unit release of the product in 1981.

Lens Specifications:

Optical design: presumably 6 lenses in 4 groups (half-symmetric plasma, in the catalog of the State Optical Institute - “Arctic”), look at the type of circuit; the light diameter of the first lens is 40 mm, the last - 35 mm;
Back segment ~ 100 mm;
Relative aperture: F / 5.6 (artificially diaphragmed), actual F / 3.5;
Aperture: 10 blades, light diameter 16.5 mm;
Field of view angle: ~ 40 °;
Designed for format: (presumably) 6x6 cm, covers ~ 8x8;
Mounting thread: M50, located in the middle of the housing.

Design and adaptation features F = 137

The lens is a modestly made lens block: the lenses are locked with two slotted nuts in front and behind; the diaphragm ring does not have a thread and runs on friction on the smooth surface of the body, fixed only with a decorative body ring and a diaphragm screw; the optics are rolled into aluminum pancakes - the lens-block design is “bulk”. Enlightenment of ordinary single-layer lenses, pink and orange. Apparently, the lens was initially made as cheap as possible and ready for mass production, but then something went wrong. In any case, apparently no one has seen more of these lenses.

The native ten-blade aperture of the lens is much smaller than the light diameter of the lenses. It allows you to use F / 5.6 as the maximum aperture. First of all, it was replaced by a nine-petal diaphragm from Industar-55U 140 / 4.5 (https://radojuva.com/2016/04/industar-55u-140-4-5/), which allows you to use F = 137 at full aperture F /3.5.

View of the converted lens F = 137

View of the lens not converted F = 137

View of the converted lens F = 137

View of the lens not converted F = 137

View of the converted lens F = 137

View of the lens not converted F = 137

View of the lens not converted F = 137

View of the lens not converted F = 137

The next step was the landing of the lens block in the body of the dead Vega-12V. After that, the shank was replaced by the B-mount, while maintaining its working distance. Then, a ring with a thread for 40.5 mm filters was planted in front. Thus, as a result, a ready-to-use 137 / 3.5 lens for medium format cameras with bayonet mount B (Pentacon Six) was obtained. To use the lens with a Canon camera, I use the P6-M42 adapter with the installed aperture (Why is this needed? See here) and the M42-EOS ring.

However, in comparison with small-format optics of class 135 / 3.5, this lens is much larger and heavier and generally looks like a Frankenstein, which it is. At the same time, it is more compact than many medium format lenses of the 120-150 / 2.8 class.

Adapted lens and adapter rings for mounting on a Canon camera

Adapted lens and adapter rings for mounting on a Canon camera

View of the converted lens F = 137

View of the converted lens F = 137

View of the converted lens F = 137

View of the converted lens F = 137

View of the converted lens F = 137

View of the converted lens F = 137

View of the converted lens F = 137

View of the converted lens F = 137

View of the converted lens F = 137

View of the converted lens F = 137

Optical properties

The optical scheme of the lens speaks of its technical purpose - semi-symmetric six-lens plasmas were used as aerial photography and reproduction lenses. Therefore, a good resolution and excellent geometry can be expected from the lens. The second on a small-format camera can hardly be checked (in any case, there are no complaints), while the first leaves mixed feelings.

When working on an aperture in excess of the stipulated F / 5.6, very strong spherical aberrations (soft) appear, coming in order after ~ F / 4.5. An open f / 3.5 aperture in small format cannot be called working after communicating with any responsible 135 / 3.5: because of the strong soft effect, it can only be used in portrait shooting. Also, the lens with apertures above F / 5.6 has noticeable longitudinal chromatic aberrationcharacterized by the color of the prefocus in red, and the out of focus in green. Moreover, it is also easy to notice spherochromatism - defocus circles have a color border.

The best image quality is achieved with F / 5.6-F / 8. The optimal aperture according to the ratio of residual aberrations and resolution is F / 4.5.

Aperture greatly affects the image of the lens: when you close the aperture, the software quickly leaves, the nature of the bokeh changes a lot - from the lurid one it becomes more calm and pleasant.

Photo at f / 3.5

Photo at f / 3.5

Photos at ~ F / 4.5

Photos at ~ F / 4.5

The presence of a bouquet of aberrations makes the circle of confusion right up to F / 4.5 edged, field distortions create a weak effect of the “flying apart” bokeh (a similar effect is especially pronounced in old 28/2 wide-angle). At F / 5.6, the bokeh becomes smoother, at short distances it seems “oily”.

The change in the nature of bokeh is clearly visible in this series of shots (F / 3.5, F / 4, F / 5.6):

Photo at f / 3.5

Photo at f / 3.5

Photo at f / 4

Photo at f / 4

Photo at f / 5.6

Photo at f / 5.6

Due to the optical scheme used, the lens collects hares from the sun well, very often a strong veil appears in the side light - the lens needs a lens hood. The consequences of "medium format" in the form of a drop in contrast due to scattering on the inner surfaces of the unused light flux are well compensated by covering the second diaphragm in the adapter (light cutter mode). In general, the contrast F = 137 can only be called satisfactory.

The color rendition of F = 137 is correct, without noticeable distortion - the merit of successfully selected enlightenment and varieties of glass.

When working with the second diaphragm mounted in the adapter, you can achieve an interesting twisted bokeh, which sometimes looks very unusual. For these purposes, the lens is much better than the "correct" Vega-23 150 / 3.5. Many photos for this review were shot using the second aperture in vignetting mode. In addition to changing bokeh, this gives a small increase in contrast and sharpness.

conclusions

This rare lens lacks stars from the sky for its optical quality, but it turned out to be quite interesting in work. In addition, I can not recall a single large-scale lens available with a similar optical design. The main drawback is the dark working aperture: after sunset or in the shade, it is extremely difficult to shoot. The advantages are the possibility of using it in a medium format (and I’m sure that the lens would have shown much better on it), good color rendering and a lot of possibilities for transforming the picture using the second aperture.

You will find more reviews from readers of Radozhiva here.

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Comments: 15, on the topic: F = 137 137 / 5.6 (3.5), KOMZ. Review from the reader Radozhiva

  • zengarden

    An interesting review and alteration :) I liked soft portraits, where the optical imperfections of the lens just contribute to the creation of a kind of picture.
    Further creative success, Rodion!

  • Michael

    Thanks for the review. But it is not clear why it was necessary to change the diaphragm? No wonder it was limited to 5.6

    • Rodion

      Well, if I hadn’t changed it, no one would have known that it’s actually lighter than a stop more than once. No one would have seen the true nature of the picture, characteristic of lenses with such a scheme - two. The lens would lose the ability to work as a soft version and would be almost useless when used with a second aperture - three. Finally, in the medium format, the use of an open aperture is much more justified, for photographic materials such as film are much less demanding on the resolution of the optics than the matrix of a cropped camera - four. Well, I can just do it - five.
      Do you see? And say that you do not need to change the diaphragm)

      • Michael

        No, well, if you want - there are no questions) A more open hole, in addition to a significant increase in aberrations for my taste, did not give anything. Bokeshka just like 5.6 likes, well, here it tastes and color)

        • Rodion

          You see, now you can say so - make a conclusion. And if the diaphragm had not been replaced, no one would have known about the true surrender of undiered glass. And if I wrote that a replacement is possible - someone would definitely say why I didn’t open it to the end, because the picture on 5.6 is promising)))

          • Rodion

            T9 is burning. surrender: = picture

          • Michael

            Yes, I agree.

  • Dmitriy

    IMHO it is better to try glass from the SF not on the worst crop - from Canon (about twice the crop m4 / 3 it is better not to remember at night), but on the FF. Even if on the first track or 1Ds or on Sonya A7m2 / A7m3 / A7Rm2 / A7Rm3.

    • Dmitriy

      Another volume in the photo and glass opens better.

    • Sven

      Yes. Better.

    • zengarden

      So give Rodion FF a camera, business :)

      • anonym

        Rodion is very offended (and in vain) by comments on the camera in previous reviews. The golden rule is that the lens is tested on a camera with a format corresponding to it ... .... The bear rides a scooter only in a circus.

  • Sven

    Thank you Rodion for your work !!

  • Alexey de Paris

    Thanks for the interesting review, a great demonstration of the possibilities! This is a really worthwhile lens with an interesting, even very interesting picture. Thank you for your patience and diligence! Very successful and interesting result! Having looked at this lens on the APS-C, I’m really interested to see what comes out in full frame!

  • Rodion

    The second known copy of this lens with the number 15 for 81 years is being sold on one of the famous Russian trading platforms. With the same characteristic damage to the anterior lens. But)

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