Film projection lens 35KP-1,8/120 adapted for use with modern cameras

Material on the lens 35KP-1,8 / 120 especially for Radozhiva prepared Rodion Eshmakov.

Photo of the adapted lens.

Photo of the adapted lens. increase.

The 35KP line of Soviet projection optics is designed to display a conventional 35 mm film frame (approximately equal in size to an APS-C frame) and includes many lenses with focal lengths from 65 to 140 mm with different optical schemes. Lenses were produced by different enterprises of the USSR: LOMO (Leningrad), MMZ (Minsk), IPZ (Izyum). This review presents a 35KP-1,8 / 120 (MMZ) lens with an installed aperture diaphragm and a focusing mechanism for use with modern cameras. My early lens review in primitive adaptation given here.

There is some confusion with 35KP-1.8 / 120 and 35KP-1.8 / 140: under the same name, two versions of each of these lenses were produced - six-lens (of the "double Gauss" type) and four-lens (of the "Kinolux" / "Kypronar" type by R. Richter) . It's easy to tell them apart - six-lens lenses are shorter, heavier and have a larger front element than four-lens lenses. While four-lens aplanats were simple, cheap, and compromises, the six-lens versions were technically superior lenses.

Specifications:

Optical design - 6 lenses in 6 groups, of the "double Gauss" type (a variation of the "Planar" scheme);

Schematic diagram of the lens 35KP-1,8 / 120.

Schematic diagram of the lens 35KP-1,8 / 120.

Focal length - 120 mm;
Relative aperture - f / 1.8;
Estimated frame format - 16x21 mm, actually covers up to 44x33 mm;
Landing diameter - 62.5 mm;
Weight - 1100 g;
Features - a projection lens, does not have a focusing mechanism and an iris diaphragm.

Design and adaptation features

The lens is assembled in a “flashlight” type body, due to which the landing diameter is only 62.5 mm, unlike LOMO lenses: the shorter focus “barrel” OKP5-90-1 has a diameter of 82.5 mm, under which it is difficult to find a focusing mechanism. To disassemble the lens, it is necessary to unscrew the front and rear slotted nuts, which are locked with screws, after which thick and heavy lenses can be removed.

35KP-1,8 / 120 uses the same circuit diagram as lenses ЛОМО ОКП4-80-1 80/1.8, OKP5-90-1 90/1.8, OKP4-110-1 110/1.8. It is interesting that in this lens, unlike LOMO optics, both autocollimation and conventional assembly methods are used. The first involves enclosing the lenses in metal frames and then centering them by turning the frame on the machine, and the second involves placing the lenses in the body without using frames. I did not find any logic in choosing lenses for autocollimation: it is clear that a very thick front lens would hardly experience problems with centering or skew, but why the rear one was left without a frame is unclear.

Taking into account my early impressions of the 35KP-1,8 / 120 and the positive experience of using the OKP4-80-1, I decided to fully adapt the 120 mm lens. The most difficult thing in this procedure is to install the aperture diaphragm in the "correct" place of the lens block, that is, between the third and fourth lenses.

The problem is that there is simply no place for the diaphragm either in terms of thickness or outer diameter, and the light diameter of the diaphragm must be at least 36 mm. For a long time, the task was technically unsolvable for me, but, fortunately, I managed to find an acceptable size iris diaphragm (D external 50 mm, D light 36 mm, thickness 6 mm), and to install it, the frame of the fourth lens was machined at the seventh surface on a lathe, leaving a thin wall so that the lens does not fall out of the frame. The procedure is fraught with serious risk and not every turner can be entrusted with it!

After finalizing the lens frame, the diaphragm was installed; to remove its drive, it was necessary to cut both in the frame of the fourth lens and in the lens body. For the convenience of aperture control, a ring was made by 3D printing.

The lens block assembly with the diaphragm was installed in a Chinese M65-M65 25-55 mm macrohelicoid, which also had to be machined in order to position the focuser closer to the nose of the lens. An M65-M65 shank was also made for setting the working length and potential use with medium format cameras like Fuji GFX, on which the M65-M42 adapter is screwed. I like the factory-made M42 threaded shank better than the one that a turner could make, because the factory adapter has a larger light diameter.

Photos of the adapted lens are shown below.

35KP-1,8 / 120 does not look like a very monstrous lens despite its impressive parameters (Tair-11A has comparable dimensions and weight, although it is twice as dark), but its mass balance is very specific due to the heavy front lens group, because It seemed to me that with my adaptation method, it would be better to use a 36-90 helicoid due to the wider focusing ring, which provides a comfortable grip.

Optical properties

35KP-1,8 / 120 may seem blurry in a cursory test, but this is a misleading impression. The lens has a very narrow depth of field and deceptive transition to defocus, so it is important to learn how to properly focus when shooting with this lens. It is also worth noting that the contour sharpness (contrast of large details) at an open aperture is really small, which can be perceived as blur. At the same time, the lens transmits small details very well. In terms of frequency-contrast response, this means that 35KP-1,8/120 has a low contrast ratio at 10 mm-1, but good at 30 and 100 mm-1.

The main reason for the decrease in image quality in the central region of the frame is spherical and (sphero-)chromatic aberration. At apertures up to F/2.8 and beyond, the lens becomes very sharp in the center.

The edges of the 36x24 mm frame are significantly affected by lateral chromatic aberrations, which is not corrected by aperture, but can be partially leveled in post-processing. At the same time, the lens along the edge of the frame is not visually inferior to Meopta Meostigmat 100 / 1.7 https://radojuva.com/2023/02/meostigmat-1-7-100-f-82-5/.

The contrast of the generated image lacks stars from the sky, but is acceptable under normal conditions. In backlight, the lens catches interesting glare, and strong color veiling can also appear - under the color of the glare of the antireflection coating. Since the reflection from the lenses is quite intense (single-layer coating), and there are already 12 glass-air surfaces in the lens, then, in combination with the light transmission profile characteristic of optics with a single-layer coating with a maximum in the yellow-green region, a complex toning of the image appears with a combination of yellow-green filtering and red-pink scattering. For this reason, bright light sources (especially yellow ones) should be avoided to obtain an acceptable image. In post-processing, you can partially remove the veil by darkening the red channel in the shadows. In cloudy weather or in diffused light, the lens has practically no problems with color reproduction.

The artistic pattern of the lens is interesting: the 35KP-1,8/120, like the LOMO OKP4-80-1 80/1.8, has very smooth defocus transitions, as well as discreet unobtrusive creamy bokeh. In this regard, the lens is not at all like the more lurid LOMO RO500-1 90/2, 35KP-1,8 / 75 and, even more so - KO-120M 120 / 1.8 (four-lens 35KP-1,8 / 120).

The lens, as it turned out, even with the M42 mount has no problems with vignetting on a 44x33 frame or with shift adapter with vertical shift. Examples of photos on Sony A7s with a shift adapter are shown below.

The following are examples without using a shift adapter on a Sony A7s full-frame mirrorless camera.

Conclusions

The 35KP-1,8/120 film projection lens is a fairly high-quality and pleasant-looking lens, but difficult to handle due to a very specific color rendering. Full adaptation of the lens is also not easy. Nevertheless, in terms of the combination of parameters, artistic properties and image quality, it is one of the most interesting among Soviet projection lenses.

All reviews of film projection and filming lenses:

  1. RO3-3M 2/50
  2. RO2-2M 75/2
  3. LOMO RO501-1 F = 100 1: 2
  4. PO 500-1 F9 CM. 1: 2 P
  5. LOMO RO500-1 F = 90 1: 2
  6. LENKINAP RO500-1 F = 9cm 1: 2 P
  7. LOMO RO506-1 F = 80 1: 2
  8. ЛЭТИ-60/60М F=92 1:2
  9. 2/92
  10. F = 92 1: 2
  11. 16KP-1,4 / 65
  12. 35KP-1,8 / 65
  13. 35KP-1,8 / 70
  14. 35KP-1,8 / 75
  15. 35KP-1,8 / 85
  16. 35KP-1.8 / 100
  17. 35KP-1.8 / 120
  18. 35KP-1,8 / 120 (with aperture)
  19. LOMO P-5 F = 90 1: 2
  20. LOMO P-5 F = 100 1: 2
  21. LOMO P-6M F=12cm 1:1.6
  22. LENKINAP OKS1A-75-1 F=75 1:2 P
  23. LOMO OKS1-22-1 F = 22 1: 2.8
  24. ЛОМО ОКС1-40-1 40/2.5
  25. LOMO OKS1-300-1 F = 300 1: 3.5
  26. LOMO OKS11-35-1 F = 35 1: 2
  27. LOMO W-53 F = 75 1: 2
  28. LOMO W-54 F = 85 1: 2
  29. LOMO OKP4-80-1 F=80 1:1,8
  30. ОКП-6-70-1 F=70 1:1,8
  31. Tair-41 50/2
  32. KO-120 1: 2,1 120mm
  33. KO-90 1: 1,9 F = 9cm
  34. KO-120M 1: 1.8 F = 120mm
  35. KO-120M 120 / 1.8 with a diaphragm and helicoid
  36. KO-120 1: 2.1 F = 12cm
  37. GOZ “KO-140” 1:2,2 F–14cm
  38. Vega-9 2,1 / 50
  39. MP RSFSR GLAVOCHTEKHPROM PLANT №6 ★ F=7.7cm ★
  40. MSO USSR SSD UPP-1 ★ KHARKIV ★ F-7 CM ★
  41. Schneider Super Cinelux 70/2
  42. Meopta Meostigmat 90/2
  43. Meopta Meostigmat 100/1.7
  44. RO2-2M 75/2 VS LOMO Zh-53 75/2 VS LOMO RO506-1 80/2
  45. Projection aplanates: "Petzvali" and "Richter"

The names of the lenses correspond to their exact spelling on the body.

You will find more reviews from readers of Radozhiva here.

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Comments: 25, on the topic: Film projection lens 35KP-1,8/120, adapted for use with modern cameras

  • Eugene

    Magic beauty!

  • Alexander Rifeev

    I never cease to admire the authors of the site's publications - they understand a lot about various photo perversions! :-)))) With the idea of ​​using an ordinary UPA-type enlarger for digitizing films of analog photography, I would not have had a hundredth of their success :-))

    • Alexander Rifeev

      Digitization of black-and-white photographic films CANON EOS 500D

      Digital camera CANON EOS 500D as a slide scanner
      A client-employer is talking to a professional killer. Killer: I was given the circumstances of your problem, sir. I undertake to solve it, the price of the issue is ten thousand ... Client: - Rubles? Killer, raising his eyebrows in surprise: - Rubles? Dollars, sir! The client smiled sarcastically: - Yes, for ten thousand dollars, I myself will kill anyone you want ... (Joke)
      I had a large number of negative black and white photographic films shot. Mine taken from 1983 to 2000, and left over from my father and taken from 1953 to 1991. Somehow the thought appeared: it would be nice to digitize them. The film, no matter how good it is, is still not eternal, and the figure is practically immortal. Moreover, a lot of shots from black-and-white films never reached the stage of positives. Entering our photo lab, I asked how much it costs to digitize a film? The girl who worked there answered that with developing and digitizing the film would cost 60 rubles. Blank (disk for recording), of course, yours. He asked, and if the old black and white negative film? She replied that she did not know for sure, but she would ask the owner. I clarified - will everything be presented already in the form of positives? She did not understand me, is it like with color film? And then I realized that the times of black-and-white photography are as far from it as the times of Ivan Kalita or Ivan the Terrible are from us. And looking into the naive beautiful eyes, I also realized that no one will ever mess with my films, bringing their scans to condition. The films are completely different in terms of the state of the photo layer and the density of the frames taken, so their scans will be given to me without bothering with their refinement. After all, the customer's color films shot by automatic cameras are all practically the same, the scanning process is completely debugged, it earns money for the owner, issuing film after film with the rate of fire of an anti-aircraft gun. So, there is nothing to hope for.
      Well then, let's do it ourselves. Three ways are possible: scan with a flatbed scanner, purchase a film scanner, reshoot with a digital camera. Flatbed scanners were not suitable for me, firstly, almost all of them are adapted for scanning individual slides or pieces of negative films for several frames. I didn't want to cut the tape. Secondly, the resolution of flatbed scanners is not enough for a high-quality negative image. The density of the negative reproduced by them is also at the limit of their capabilities, in fact no more than 1,7-1,8, for an ordinary black-and-white negative film it may be enough, its density is not more than 1,5. But for the color is no longer there. Its density reaches 2,5. The flatbed scanner type HP 4600 with a separate adapter for scanning films was praised on the net. But it is not on sale in stores, and it is not even in catalogs, and sellers do not know what it is. And its cost will be about 12-15 thousand.
      Cheap amateur film scanners for 5-7 thousand did not suit. With a resolution of 5-6 megapixels, the quality of their scans will be poor. The cheapest good film scanners started at 17-30 thousand. Then, after scanning the archive of black-and-white films - what to do with it? The only way left was to reshoot the negatives digitally. I have digital camera CANON EOS 500D. It is clear that in terms of the quality of scans, it will also yield to real professional film scanners, but I was not going to impress the public with my black and white photographs, its quality is quite enough for the home. And here again there are several options. The size of the black-and-white negative is 24x36 mm, and the matrix of digital cameras is 15x22 mm. So macro photography. Shooting with a branded 50mm macro lens costs 15 thousand. Extension rings: branded ones cost - 4600. Shoot with a "flip" lens. You can, but you will need a 58 mm / bayonet adapter. It costs 900 rubles. But in this case, the automatic lens will no longer work. It will be possible to set the required aperture through the button for viewing the depth of field on the digital lens and without releasing it, remove the lens from the digital lens and then put it back on the digital lens through the adapter. But this is still a hassle, like how to cauterize the tonsils through the anus in the legendary Soviet joke. In addition, I suspect that the standard zoom 18-55 / 3,5-5,6 is hardly suitable for such quirks. There was a way - to marry a horse and a quivering doe ...))))
      From the Soviet photographic equipment that I had, I take a set of extension rings with a fitting thread with a diameter of 42 mm for the lenses of the Zenit camera and the Industar-61l / s-MS lens. It was once considered a very good macro lens, allowing you to focus from 25 cm. But they still need to somehow make friends with the digital camera CANON 500D, which has a mount instead of a 42 mm thread for attaching a lens. Sold on the Internet adapters 42 mm / bayonet. But they cost 900 rubles, wait for their arrival for about a week, or even more. Therefore, I take a plastic cap to the CANON camera, having found the center, I mark a circle with a diameter of 41,5 mm with a compass. I cut a hole and put the shortest ring from the set of extension rings to the Zenith into the plug on the thread. Here, too, there are two options - to plant the ring deep into the plug or to plant it only on the connecting thread. I did not dare to plant deeply, forming rings with a diameter of about 53 mm, if a little smaller by 1-1,5 mm, then it would be just in place. And so it is possible to destroy the stub itself. Therefore, I planted only on a 42 mm thread. And after that, the Industar-61l / s-MS lens can only be used for macro photography.
      And it turned out what you see in the photo at the beginning of the article. Zf CANON 500D on a tripod with an Industar-61l / z lens, between them a plug is tightly connected to a short ring, the middle ring from the set of rings for Zenith is screwed onto it. The photo enlarger UPA-601 was installed on the rod in an inverted position. The lens with the focusing unit has been previously removed. Instead of an incandescent lamp - a daylight lamp with a power of 18 watts.
      Shooting options. The shooting mode is aperture priority. Shooting with a 2 second self-timer. Quality instead of the maximum possible 15,1 Mp in CANON 500D, only 8 Mp is installed. With a quality of 15,1 megapixels, sharpness will be worse due to the graininess of the negative. White balance - fluorescent lamp or automatic. Picture Style - Monochromatic with increased sharpness and contrast. The aperture on the Industar-61l / z lens was set from 5,6 to 8, depending on the density of the film being shot. It was selected for each film by comparing the brightness and image density of the first filmed negative on the digital camera monitor during focusing and the image immediately after shooting. Why not 11 or 16, as is often advised? It is believed that the sharpest images are obtained at apertures from 5,6 to 11. But in our case, apertures of 16 or 11 will not give the expected sharpness. The reason is diffraction, which depends on the installed aperture and the particle size of silver halogen on film or pixels on a digital camera matrix. There is an empirical dependence of the aperture on the size of pixels or silver halogen particles, at which diffraction still does not noticeably worsen the sharpness of the negative or the image on the matrix. If we determine the pixel size of a digital camera matrix, then the maximum possible aperture at which diffraction does not yet affect sharpness = twice the value of the matrix pixel size. For CANON 500D with its 15,9 megapixel sensor, this will be:
      Matrix area 22,3 mm x 14,9 mm = 332 sq. mm. Matrix pixel size: 1) square root of 15 / 900 = 000; 332) 219mm / 2 = 1 mm. The maximum possible aperture is 219 x 0,00456 = 4,56. In articles about diffraction for CANON 2D, it was even indicated that only - 9,1. Let's take the maximum possible aperture equal to - 500. Here there is another problem of a sharply depicted space. With a circle of blur of the negative of 7,9 mm for medium format cameras with an aperture of 8; shooting scale 0,033:5,6; it is 1 mm, at aperture 1,5 it is already 1,39 mm, at aperture 8 it is already 1,98 mm. But the circle of confusion for 11 x 2,72 mm digital matrices is only 22 mm. And so the depth of the sharply depicted space will inevitably increase. Not much, really... ))))
      Images obtained on a digital camera CANON 500D when shooting black-and-white film negatives were processed by the FastStone Image Viewer program. It is completely free and Russified. Weighs about 5,4 MB
      http://www.faststone.org/
      The negative was inverted by a computer program into a positive, the contrast was increased, sharpening was increased if necessary, and shadows or highlights were corrected. No retouching or additional processing was carried out. This will be in the future. I just wanted to show what happens when reshooting negative films with a digital camera in amateur conditions with actual cash costs of 00 rubles 00 kopecks. Alexander Rifeev

      • Rodion

        What is the point of writing this in a comment if you can arrange it as a small article and, for example, send it to Arkady for publication?

        • Alexander Rifeev

          you can of course :-))) but they are unlikely to waste space on the site for the sake of a long-tried and well-known idea :-)) this article is like 10 years old, and the fact took place in 2011-12. ... now no one is engaged in digitizing films in amateur conditions

  • grindamere

    Can low lens contrast cancel out a camera's low dynamic range? For example, on the D700, when shooting complex landscapes, lights are often knocked out and you need to use bracketing. Or is the review implying a different contrast?

    • Rodion

      The contrast in the review is assumed to be general, that is, low-frequency, unless otherwise indicated. Low contrast cannot compensate for DD, since both low DD and low contrast result in loss of information when converting space into an image.

    • B, R, P.

      An odd question to say the least.

      • grindamere

        Well, why not. If you open an image with a low DD in any graphics editor, that is, with two elevations along the edges of the histogram, and move the contrast slider to negative values, then these elevations will creep towards the center, forming a dome, partially correcting the low DD.

        • Rodion

          There is no more information from this.

  • TSerg

    Good review. Thank you, Rodion, for the work done.
    The lens is good to fight off the attackers, given its weight.
    Very nice bokeh, I liked it. And what kind of MDF does this monster have?

    • Rodion

      MDF with a helicoid stroke of 30 mm turns out to be approximately 60 cm.

  • BlackProfessor

    And what about this lens with the depth of field zone? Banana or not? And then something really looks like a picture from him like that from his “big brother” - a 6-lens 35KP-1,8 / 140 ...

    • Rodion

      In terms of? It's a planar, it has a flat field. The curved field of the 35KP/KO four-lens lenses, which are aplanats. The six-lens 140 / 1.8 is also a planar, but with a simpler 6/5 scheme (versus 6/6 for 120 / 1.8). In my opinion, 140/1.8 or 100/1.8 will be worse than 120/1.8.

      • BlackProfessor

        Projectors will still not have an ideally flat image field with depth of field zones equidistant from the plane of the matrix or film; figures.
        By the way, this is an interesting topic for research, especially if there is a hardware and instrument base for it. Moreover, I think that not only projectors can present surprises during the study.
        I bought here on the occasion of the Vivitar Series 1 90-180 / 4,5 with the proud inscription “Flat Field”, and so, I am eager to explore, in artisanal, so to speak, conditions, how “Flat” this lens has is the “Field” ))

        • Rodion

          For any fast lens, the shape of the field is far from flat, specifically the projectors have nothing to do with it. I'll tell you more - the shape of the field there can easily be neither a sphere nor a meniscus. You still do not take into account astigmatism and aberrations of higher orders))))

          • BlackProfessor

            I know, I know that I don’t take everything into account))) After all, I’m not an optical specialist, but a practicing photographer and a bit of a techie.

  • BlackProfessor

    UPDATE.
    If you are adapting film projectors to work with a mirrorless full frame, then it is best to take a shank with a Canon EF mount, because. it has the largest internal diameter - 48 mm.

    • BlackProfessor

      Then, in a similar way, the adapted lens can be installed in addition to the mirrorless full frame also on the mirrorless medium format.
      The large bore diameter of the EF mount will further ensure that there is no vignette.

      • BlackProfessor

        Adapted projector for Fujifilm GFX 50R.

    • Rodion

      In general, everything is correct. For convenience, I made an M65 / M42 shank for my lens, so that if necessary I could put the M65-GFX adapter. Although with the M42 there will not be much vignetting at 44x33 - the rear lens is small in diameter.

      • BlackProfessor

        I have not used either shanks or adapters with M42x1 thread for a long time, and here's why.
        It has been noticed that lenses with this thread do not always fit exactly into the camera's threaded socket, or into the same adapter.
        In particular, the famous Pentacon 135 / 2,8 (Bokeh monster) fits into the adapter so that the central zero risk on the lens is not in line with that on the adapter, that is, the lens (and not only the Pentacon!) rises when tightly twisted into the adapter at some angle.
        As an example, I give a photo of the installation of this Pentacon in the M42-GFX adapter.
        The problem, in general, is purely cosmetic, and the M42 threaded connection on this adapter can be adjusted to the desired angle of rotation ... but it still looks clumsy.
        Therefore, I will convert almost all my lenses with the M42x1 thread, except for rare ones, either to the Canon EF mount or to the Pentax K, depending on which of these mounts will be most aesthetically justified on a particular lens.

        • Rodion

          Oh, well, this is already something very frozen)))

          • BlackProfessor

            Well, this is my personal quirk, so to speak.
            That same Pentacon bockenator will soon sport a new heel counter with an EF mount.

          • BlackProfessor

            And how do you like such absurdity?
            MC Kiron 105/2,8 Macro lens with Pentax K mount, 2 adapters: PK-EOS and EOS-GFX.
            The PK-EOS adapter is crooked, and the company that produces it, K&F Concept, has not raised any questions about the quality of the products to this day. Most likely, this is a technological marriage at the design stage.
            I did not want to have a crooked lens mounted on Fuji, so I bought a “straight” PK-GFX adapter from the same company, and with it the lens was already straight on the camera.

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English version of this article https://radojuva.com/en/2023/05/35kp-1-8-120-2/

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