Quick Summary-Industar 28/2.8

[OlDoinyo]

I have been curious about some of the old cheap lenses I have seen on Ebay and wondered what their suitability for UV might be. A few weeks ago, I blew the princely sum of USD16 on an Industar 28/2.8, an old Soviet lens probably meant for a rangefinder camera when manufactured. It was stated to come with an M39 mount, and I verified that M39-to-Minolta-A adapters were available, so I ordered one of those (almost as costly as the lens itself.) Imagine my dismay when I received the items, mounted them on the camera, and the image (even in the visible) was not remotely in focus. Infinity focus resulted in maximum sharpness about 4 cm in front of the lens.

 

I did some reading, and it turns out that there is more than one kind of M39 mount: in particular there exists an older kind (M39-LTM) with a flange focal distance of 28.8 mm, and a somewhat newer one (M39x1) with a flange focal distance of 45.2 mm, meant for SLR use. The adapter I purchased is most likely of the M39x1 specification, while the lens (as I verified by focusing an image on the palm of my hand) appears to be of the M39-LTM specification, which makes it physically impossible to mount it on an SLR at normal focus, as the rear of the lens would protrude far back into the mirror box. Clearly, there will be no landscape photography with this lens, at least on an SLR.

 

I nonetheless persevered and conducted a few quick tests. First came the pinhole bandpass test, with the Sony A900 and the Baader U2 filter (display intent BGR):

 

 

The color shown is relatively modest, much better than that shown by the disappointing Enna 28mm lens; I would place the cutoff somewhere between 340 and 350 nm, comparable to that of the Asahi 35/3.5 and very respectable for a 28/2.8 optic. Were it not for the FFD issue, this lens might have been one of the better candidates in its focal length range.

 

I next bodged together a lens-front adapter out of stepper rings and tape so that I might be able to get some idea of the image quality. The setup leaked and caused there to be artifacts in the test frames, but that is of no real consequence. A somewhat weatherbeaten Rudbeckia flower provided subject matter of suitable scale.The lens was so close that the camera itself blocked quite a lot of light from falling on the subject, which is one reason one does not generally use wide-angle lenses in close-up work; but never mind. ISO was 800 for these frames:

 

 

I had some problem with wind when shooting these, but the image quality on the whole seems respectable, without excessive CA. In conclusion, the best UV application for this lens would probably be on older film cameras of the M39-LTM specification. Adapting the lens to mirrorless digital cameras might be theoretically feasible, but finding an M39-LTM adapter to a modern mount is a serious challenge. The long FFD of SLR-type cameras make this lens impractical to use on them. The quest for a better wide-angle lens continues; there is a Zeiss-Jena 28/8 that was made in the 1930s, but there is clearly no way of mounting that lens on any equipment of mine, so I am not in a position to evaluate it.

[enricosavazzi]

[...]

In conclusion, the best UV application for this lens would probably be on older film cameras of the M39-LTM specification. Adapting the lens to mirrorless digital cameras might be theoretically feasible, but finding an M39-LTM adapter to a modern mount is a serious challenge.

[...]

M39-LTM adapters for Micro 4/3 cameras are readily available and very cheap on eBay. I think I have seen adapters also for maybe half a dozen other mirrorless mounts.

 

There are some concerns about achieving infinity focus with this lens (I have not tried this lens yet), but modifications to allow this seem feasible, for example see http://www.onemorelens.com/2011/07/industar-69-28mm-f28.html

[OlDoinyo]

It is possible that a M43 SLR camera might have a short enough mirror box to permit mounting an M39-LTM lens at its rated distance. But this lens would not be a wide angle with such a camera; it would be rather more like a longish normal lens. In fact, the test frames above show the lens at an effective focal length of about 45mm (due to the very close focus,) so it is not much of a wide angle even there. Whether the lens's image circle would have covered the A900's FF sensor at infinity is an interesting question. To find a UV wide angle for a M43 camera, you might have to look at old C-mount cinema lenses, some of which are as short as 10mm.

[enricosavazzi]

It is possible that a M43 SLR camera might have a short enough mirror box to permit mounting an M39-LTM lens at its rated distance. But this lens would not be a wide angle with such a camera; it would be rather more like a longish normal lens. In fact, the test frames above show the lens at an effective focal length of about 45mm (due to the very close focus,) so it is not much of a wide angle even there.

This is the problem with legacy lenses on Micro 4/3 cameras. I had an even bigger problem with lenses for the Gopro Hero, but did manage with a 6 mm in D mount.

 

The Sony full-frame mirrorless cameras are an opposite solution to the same problem, of course. If the lens does not fit the camera, get a camera that fits the lens.

Whether the lens's image circle would have covered the A900's FF sensor at infinity is an interesting question. To find a UV wide angle for a M43 camera, you might have to look at old C-mount cinema lenses, some of which are as short as 10mm.

I did not have much success with legacy C lenses. Several of them (Kern Paillard for example) are now too expensive to buy them on a hunch. Dito the "half-frame" Olympus lenses for Pen F (although the 38 mm is known-good for UV). I had better luck with the 18 mm f/2.8 Pentax-110.

 

I now have an Industar 28 mm on order, and will report about its performance on Micro 4/3 in due time. Given the small size of this lens, it might be useful to carry in the UV kit bag together with the "midget-sized" Pentax-110 18 mm.

 

Filter adapters are of course a problem. I will probably start with an old 22.5 mm second-hand color filter and build a step-up adapter around it. I standardized on 30.5 mm filters for use on the Pentax-110 lens, so this size should work also on the Industar.

[Alex H]

This lens is designed for half-frame camera.

[Andy Perrin]

Is half-frame roughly the same size as APS-C? Wonder if it would be good for my NEX-7.

[OlDoinyo]

Half-frame is roughly 16 x 24mm, I think.

[JCDowdy]

The Olympus PEN F half frame film camera was 18x24

 

I do not know about this Soviet camera.

[OlDoinyo]

https://en.wikipedia.org/wiki/Chaika_%28camera%29

[Andy Perrin]

Wiki says for APS-C, "Sensor sizes range from 20.7×13.8 mm to 28.7×19.1 mm, but are typically about 22.5×15 mm for Canon and 24×16 mm for other manufacturers" which certainly sounds close enough!

[enricosavazzi]

A quick look at this lens (got mine, but still no M39 short adapter for Micro 4/3) shows a potential problem with access to the aperture ring, which is a very narrow thing around the filter mount. After a step-up filter adapter is mounted on the filter mount, the aperture ring is inaccessible.

 

The only solution I can think of, other than using rear-mount filters, is epoxying a second step-up adapter (Edit: the best fit is a 30mm - 37mm step-up ring) around the aperture ring, to increase its diameter. The step-up filter adapter (22.5 to 30.5 mm) can then sit slightly in front and within the aperture ring step-up adapter, and both are accessible. Aperture is adjusted by turning the larger of the two step-up adapters. This modification is best done after testing/adjusting the lens for infinity focus on one's camera.

 

Edit: the adapter to epoxy on the aperture ring, if left unmodified, hides the aperture index and aperture scale. It is possible to avoid this by cutting off the 37 mm threaded ring and flat flange from this ring for about 1/8 of the perimeter. The inner ring with the 30 mm thread is best left uncut.

[enricosavazzi]

I was able to recalibrate the lens so that it focuses at infinity on an L39 to Micro 4/3 adapter, by following the instructions at:

http://tunnel13.com/blog/industar-69-easy-infinity-focus-fix/

 

A side effect of this procedure is that the aperture scale no longer applies, but as noted at the above link, there is a simple workaround (it might even be possible to recalibrate the aperture scale by further disassembly of the lens).

 

The focusing range is now from infinity to about 0.4 m, i.e. a significant improvement on the original 1 m closest focus distance.

[OlDoinyo]

The focusing range is now from infinity to about 0.4 m, i.e. a significant improvement on the original 1 m closest focus distance.

 

Did you include UV-infinity in the expanded focusing range? The method quoted uses visible light to set infinity, which might leave UV-infinity still out of range.

[enricosavazzi]

Did you include UV-infinity in the expanded focusing range? The method quoted uses visible light to set infinity, which might leave UV-infinity still out of range.

No, this is only VIS calibration so far (plus a little margin that might or might not be enough to allow for UV/IR "focus shift"). Before I can mount a UV-pass filter on this lens, I need to fix a filter adapter and an extension for the aperture ring. Infinity focus can always be recalibrated by loosening the set screws and rotating the focus ring, without disassembling the lens (which will be impossible with an adapter epoxied around the aperture ring).

 

An idea I might go forward with is a 30mm to 30.5 mm step-up ring epoxied around the aperture ring, which would work both as an aperture ring extender and as a filter adapter. I do not plan to use polarizers with this lens, so the fact that the filter will rotate with the aperture ring is not a problem.

[Dmitry]

I was able to recalibrate the lens so that it focuses at infinity on an L39 to Micro 4/3 adapter, by following the instructions at:

I made the modification of the adapter L39-m4/3 - polished the ring on the adapter for a fraction of mm. No need to calibrate aperture scale.

Still looking for filter adapter.