A review of a homemade 50 / 3.5 achromat lens from gluing a Zenith-TTL viewfinder from a reader of Radozhiva

An unusual review specifically for Radozhiva, prepared Rodion Eshmakov.

View of the lens assembly

View of the lens assembly

Achromat lens is a type of lens in which spherical and chromatic aberration are corrected in the absence of correction of distortions of inclined beams - coma, astigmatism. Achromats are one of the simplest schemes, they are widely used as technical lenses - especially in observation instruments, microscopes, etc. For example, achromatic lenses are the lenses of most binoculars, and achromatic telescopes are widely popular due to their low cost and acceptable quality.

Schematic diagram of the achromatic lens

Schematic diagram of the achromatic lens

Among the photo lenses, only old small format super telephoto lenses with a focal length of more than 500 mm are represented by achromats. But in modern times, such a scheme is used only in creative lenses like Lensbabywhere the lens aberration is used as the effect.

Achromat production from the Zenith camera viewfinder

Cameras like "Zenith" are very common at the present time, including and inoperative. In the vast majority of cases, they are of no interest either to collectors or to amateur photographers. However, it turned out that from Zenit cameras you can get not only a lot of screws, a scratched mirror and a piece of plastic with a micro-raster - a single gluing, which serves as the eyepiece of the video finder, is of interest. The focal length of this gluing is approximately 50 mm, it is achromatic, because scheme JVI no longer contains other lenses (in contrast, for example, from gluing lenses of Industar - it is part of the optical scheme and is not an achromat). The relative hole for gluing from the Zenith-TTL visor is approximately F / 2.8-F / 3.5 (since the exact FR has not been measured). Those. there is the possibility of manufacturing a “creative” lens with parameters convenient for shooting (unlike achromatic lenses from glued binoculars, etc.).

By removing the top cover of the camera, you can access the lens of the viewfinder and unscrew it. A significant disadvantage is that the lens itself is rolled into a frame, which limits its light diameter. Therefore, it is necessary to carefully cut the frame and remove the lens.

The lens seems very similar in size to Industar-50 lenses, which makes it tempting to use the body of this common lens as a donor for a helicoid and diaphragm. But - you can culturally install a lens if you previously install it in the front lens block I-50. The main difficulties that arise in this are the presence of a negative lens rolled into it by Industar and a larger bonding diameter JVI Zenith The file does its job. The main thing is to do it carefully and wisely, or it is not possible to disturb the alignment.

It is interesting that the thread of the mount of the sighting device to the camera is completely identical to the thread of the rear lens unit of a conventional Industar-50. That is, “hacky” achromat can be made without any tool at all - by removing lenses from the I-50 and inserting achromatic gluing into its body. Why "hacky"? - Because the diaphragm will be installed then in front, and the angle of view is limited by the frame of the front lens block. In addition, you will have to adjust the back section of the rings.

After refinement of the front lens-block of Industar-50, gluing-achromat is easily fixed in it, and you can use the native retaining ring of the front lens-block.

Next, you just need to set the working segment with adjustment rings, and you can find the infinity exactly if you unscrew the front lens block with achromatic gluing, and then fix it with a small drop of cyanoacrylate in the right position.

View of the lens assembly

View of the lens assembly

As a result, we get 50 / 3.5 achromat in the Industar-50 case - the construct is completely identical to it.

Optical properties of achromat 50 / 3.5 from the eyepiece of the OVI camera Zenit

In fact, it is difficult to call this gluing achromat (binocular lenses are much better in quality) when looking at the pictures: both chromatism and spherical aberration are very poorly correlated - software to a greater extent can only be leveled at F / 5.6 and beyond. Although in comparison with a monocle with the same parameters, this lens looks really good.

Picture on the "portrait" distance at F / 3.5

Picture on the "portrait" distance at F / 3.5

Picture on the "portrait" distance at F / 5.6

Picture on the "portrait" distance at F / 5.6

Due to the curvature of the field, the edges always turn out blurry, in addition, field aberrations always reign there and there is no sharpness there on F / 16. On the APS-C frame format, only 1 / 4-1 / 3 of the center area of ​​the frame is sharp with an aperture of F / 3.5 to F / 11. By the way, this distribution of sharpness over the frame is the main artistic property of the lens: blurring the edges allows you to focus on the central object and, in addition, create the effect of a quick movement towards it. It's funny, but the blurring of the pre-focus zone is remotely similar to the Helios bokeh - it is also very twisted.

Reflection with glass (prefocal blur picture created by droplets on glass), F / 3.5

Reflection with glass (prefocal blur picture created by droplets on glass), F / 3.5

Achromatic gluing has no enlightenment, the contrast is satisfactory. Color reproduction is natural, but the broadband secondary spectrum on F / 3.5 tends to distort it somewhat. Apparently, in an open aperture, the lens should be used in monochrome shooting mode.

To summarize - we should not talk about the optical quality of this lens. Its merits are its shortcomings. And vice versa.

Conclusions

Gluing eyepiece from JVI Zenith cameras are a very affordable and convenient material for making your own analogue of Lensbaby. The result obtained is more than enough for any "creative" ideas. There is no optical quality - the lens is not suitable for normal shooting.

You will find more reviews from readers of Radozhiva here.

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Comments: 143, on the topic: Review of a self-made achromat lens 50 / 3.5 from gluing a Zenith-TTL viewfinder from a reader of Radozhiva

  • Arkady Shapoval

    People who have added more than 100 comments here.
    At the same time, the table of contents of this article indicates that the review is from the reader, if this is not interesting, you can continue reading further, for example, about the same a9 (previous post).

  • Michael R.

    Arkady,
    thanking only Rodion for the large number of comments, you are not entirely fair ...
    We must also thank Simon.
    It was he who, having remarkable technical knowledge, built a pinhole camera from a 5D camera.
    I took a bunch of pictures, put a lot here
    and then very energetically and enthusiastically defended his opponents
    and as the artistic value of your photos and as your creation ...

    2 Simon we can wave - I'll give you a camera obscura - you give me 5D.
    I have 100 bucks in addition .. Indeed, why do you need 5D //

    Arkady,
    I flooded a little ...
    but you yourself allowed ..., however, in the next branch, about Sonya ...

    • Arkady Shapoval

      Yes, okay, there are thoughts on the case.
      Thank you all for the discussion :)

    • Simon

      You will do something like that then you will act ... Keep your offer for yourself ... do not pray to the camera if your hands are crooked ... I know a lot about my camera and you will never take such pictures ...

      • Vania

        I will cut out your words from the monitor with a clerical knife and hang them in a frame on the wall, as a reference example of the use of strong artistic expressive means "get it first" and "All p_do_as, and I am d'Artagnan!"

      • Onotole

        Exactly, this is the classic "get it first!"

        And to yourself, dear Simon tried to apply this principle? Many Savetsky lenses were cut to criticize here?

  • Simon

    Do it at least ... And leave obscene language to yourself beautiful. I love people, I take pictures of them ... But who simply purrs without practice, I do not respect. Chatterboxes from the USSR.

    • Onotole

      Judging by your comments and _ especially_ by the pictures, you do not just dislike people, you hate them fiercely, with every cell of your body.

      And you obviously love only yourself and all that you do.

  • Ivan

    Guys, let's get more photos and reviews and less cheap flooding. This way you raise the site but discourage the desire to read comments. Who among you is more eloquent talented and so on, leave yourself the truth. Here photographic topics and inform people are also interested in NORMAL communication. I liked all the pictures in the comments, I never tried to shoot like that. Simon Zengarden and Rodion SPS for the pictures and it’s good to fight already.

    • Peter Sh.

      I had to re-read. Actually, Simon is here, at all around. He can’t understand in any way that such behavior is unacceptable.

  • Simon

    I will no longer ... There is a seed in everything, creative ...

  • Evgeny_d5000

    So, Rodion and Simon do the same thing, albeit at different levels. Namely, they use non-standard features of what they have. Yes, at different levels, but it is this desire that leads many to this site. I think both the one and the other, were delighted with the result, with all the external unpretentious means.
    I wonder why other visitors swear and what they want to see. Review d900? So wait a bit, wish Arkady patience and perseverance, and he will definitely test this decent device :)

  • Nikita

    Simon washed down another photo with the girls)

    • dragon yes not snape

      Indeed, Simon, washed down!

  • Eugene

    Simon, I was really surprised by the pinhole from 5d, thanks for opening the horizons!

  • Bethanyuaf

    My friend and I went camping the other day. It was a tiring experience, as he wouldn't let me sleep all night. He kept talking about random stories and cried about his wakefulness. I totally told him to read more and deal with it.

  • Bethanyvir

    Hey everyone! Lately I have been battling with a lot of challenges. Friends and doctors keep telling me I should consider taking meds, so I may as well this and see how it goes. Problem is, I haven't taken it for a while, and don't wanna get back to it, we'll see how it goes.

  • Rodion

    Made the same one out of the old broken Zenith-B lens. It turned out to have a FD of ~ 45 mm (i.e., less than this one) and with enlightenment, and even a different shape. In general, the picture is much sharper and better quality. It seems that the newer the zenith, the more freebies on its seeker.

    • Lavr kosnik

      I really want to try to make the same lens, but please clarify at least a little. I honestly don’t understand how I sawed through the eyepiece frame and freed the achromatic gluing from the threaded frame, and then put it in the frame of the front lens unit with my own thread? Indeed, in order to place the achromatic gluing into the frame of the front lens unit, you must first remove the native lenses from this frame of the front lens unit, which are pressed into this frame with a thread, and this cannot be done without sawing the frame of the front lens unit. And if this is done, then how, having damaged both the frame itself and its thread, put the achromatic gluing into it, and then put this front lens unit frame with gluing in its place, with the damaged thread. Thanks.

      • Rodion

        Actually, you yourself said what needs to be done. Yes, it’s cruel to cut, remove, finish the native lens frames to the gluing diameter so that it is centered automatically during installation and fixed.

  • Lavr kosnik

    Rodion .. How can I learn a little more about all the stages of rework? How to release achromatic gluing is more or less clear, but I would like to hear from you exactly how you did it, where you sawed it .. How to put achromatic gluing into the front lens unit, which should eventually be also in a threaded frame for installation into the front lens unit - it is completely incomprehensible. Thanks.

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