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Industar-69 28mm f/2.8 for UV

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#1 Bernard Foot

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Posted 15 May 2021 - 15:04

I was looking for a second Lithagon 28mm lens for a 2-camera stereo setup but these are scarce and overpriced. But there were lots of Industar-69 28mm f/2.8 lenses. This was a new lens to me, although it has been briefly discussed on UVP at https://www.ultravio...y-industar-2828 .
Anyway, I bought a couple of these and did some work on them. Here are the fruits of my labours, inc. suggestions to tackle the problems mentioned in the other thread.

Summary (a.k.a. Spoiler)

Not one of the world’s great lenses, but perfectly usable for general UV photography (e.g. using a Baader U) with some real advantages and some odd quirks.

About the Lens

Made in the USSR 1965-1975, specifically for the Chaika 35mm half-frame camera. As a result, it will cover sensors up to APS-C, but not full frame.

All Industar lenses are of the Tessar design.

The Industar-69 has a standard M39 screw thread – apparently the intention is that you could also use it on your enlarger. However, the Flange-Focal Plane distance is 27.5mm rather than the Leica standard of 28.8mm (Why did they do that???): this causes some issues with fitting to a camera – discussed later.

There are two features immediately apparent:
  • The lens is plentiful (mainly from former Soviet Union – about 2 million were made) and cheap (£25-35).
  • It’s small and light. It’s the only lens I have bought where the postman delivered it through my letterbox. Here is a comparison of size with some other UV-friendly lenses, including E-mount adapters and filter mounts.
Attached Image: Size.jpg

The small front element (compared to the Lithagon) allows use of smaller filters.

I believe the filter mount is 22.5mm. This is too small for most purposes. I couldn’t find any step-up rings – and anyway, these would prevent setting of the aperture. The aperture is set by twisting the ring around the lens, which is very fiddly and difficult to do without moving the focussing ring. A filter mounting idea is covered later.

Attached Image: Industar.jpg

UV Reach

The Industar-69 can make images using 380BP20 and 345BP25 filters, meaning that it is fine for photography through filters like the Baader U, and it transmits UV better than many other lenses people are using happily for UV. However, by 320nm (315BP20 filter) there is no transmission, so it cannot work for applications like Tri-colour.

This chart gives exposure factors through various filters for a number of UV-friendly lenses - the lower the factor, the better.

Attached Image: UV Reach.jpg

Image Quality

On the internet you will find people saying the lens has severe vignetting and is so poor you cannot even trigger focus peaking. I can only assume these people were using the lens on a full-frame camera and using a standard LTM adapter.

I found the central image resolution to be pretty good – and excellent in UV. However, resolution drops off sharply towards the edges. So the lens is fine for things like flowers and people, but not ideal for landscapes. Vignetting is no worse than other comparable lenses.

Attached Image: Resolution.jpg

Fitting to the camera.

The Flange-Focal Plane distance of 27.5mm means that you can’t use standard LTM adapters (if you want infinity focussing). There are various solutions/workarounds on the internet, but these are all based on using a standard LTM adapter.

Sony E-mount has a Flange-Focal Plane Distance of 18mm. So a different approach that works well for Sony E-mount (and should also work for Canon EF-M) is to:
Fitting Filters

The 22.5mm filter mount will be of no use to most people. Fortunately a Step-Up-From-30mm ring fits snugly outside the aperture ring grip and sits on the aperture ring. So I epoxied one of these in place - the aperture is now changed by turning the filter mount.

This obscures the aperture scale, so I put an index mark on the outside of the new filter mount and stuck an aperture scale on the outside of the focussing ring.

On the 2nd lens, the 30mm step-up ring was just too tight. So I used a 30.5mm step-up ring, but it would probably have been better to grind a 30mm ring out slightly.

Attached Image: Final.jpg

Edited by Bernard Foot, 15 May 2021 - 15:06.

Bernard Foot

#2 Andrea B.

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Posted 19 May 2021 - 17:32

Cool, Bernard! I have wondered about the Industar lenses also.
And thank you for elaborating on the adaptations using O-rings and extension tubes. This is quite useful background knowledge for those of us who use strange and unusual lenses off the 'Bay.

I don't quite understand where you put the O-ring? Is it inside the mount changer plate? the extension tube? Or just sitting on top of it?
Andrea G. Blum
Often found hanging out with flowers & bees.

#3 Bernard Foot

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Posted 25 May 2021 - 08:49

View PostAndrea B., on 19 May 2021 - 17:32, said:


I don't quite understand where you put the O-ring? Is it inside the mount changer plate? the extension tube? Or just sitting on top of it?


You can just see it in the photograph. It is around the outside of the male thread of the lens (adapted to M42) which screws into the female M42 thread of the extension tube. A 2mm-thick O-ring works well.
Bernard Foot

#4 Andrea B.

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Posted 25 May 2021 - 08:56

oh cool. Now I "see" it. Thx Bernard. :grin:
Andrea G. Blum
Often found hanging out with flowers & bees.