Converting a Schneider 82.5mm/f2 Projector Lens for Photography

Discussion in 'Adapted Lenses' started by Turbofrog, Jul 15, 2017.

  1. Turbofrog

    Turbofrog Mu-43 Hall of Famer

    Mar 21, 2014
    I've often been curious about the idea of converting projector lenses for photography. Typically they're very high quality glass, wide aperture, and corrected for wide open shooting (naturally, since they have no iris!) They are also by far the cheapest way to pick up fast, long focal length lenses. Old Nikkor or Canon FD fast 85s regularly sell for well over $100, even with fungus and haze. So when I saw a Schneider Kreuznach Super Cinelux 82.5mm/f2 for sale on The Auction Site for $50, I figured "why not?"

    The first step was determining what I would need to make the conversion. Fortunately, this is relatively well-trodden ground, with lots of evidence of successful conversions on the internet. Nowhere as elaborate as @gnarlydog australia@gnarlydog australia 's impressive work.

    Schneider actually publishes information about their more current projector lenses on their website (where I discovered that my lens retails for $2,235!), and while my lens is older and has slightly different dimensions, it was a good starting place to figure out the back focal distance and order the right bits and pieces.

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    The Conversion

    The necessary components I needed to make the conversion were:
    1. M42 extension tubes I got a (7/14/28mm set). This is to glue onto the lens itself to provide a mount for the focusing helicoid. $6 if you aren't impatient and can wait for shipping from China.
    2. A 17-31mm M42-M42 focusing helicoid. $22. I got it from Rainbow Imaging, who sell the same adapters as the Chinese retailers, but ship from the US, so you get it much, much faster.
    3. An M42-M4/3 adapter. I already had a standard flange distance version (~25mm), but I wasn't sure the lens would fit with the helicoid, so I bought a "slim" adapter for $8 which is only 5mm long, giving you a lot more flexibility in your adapter stack, especially for lenses that have shorter back focal distances. I didn't end up needing the slim adapter.
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    The inner ring of M42 extension tubes is almost a perfect friction fit for the 39mm diameter of the Super Cinelux's rear body. I started judiciously with sandpaper, and almost got it to fit, but then got impatient and set it up in my microlathe to take off the last fraction of a millimeter. Basically, once you sand off the black anodizing and see the aluminum underneath you've sanded it enough.

    I then slipped the 7mm extension tube onto the back of the projector lens, and screwed in the helicoid and the M42 - M4/3 adapter.

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    Since it was only held in by friction, I was careful to hold the lens at all times, then went into the backyard to calibrate the position of the extension tube for infinity focus. I measured the distance so it would focus ju-u-ust past infinity, just in case a little bit of glue got on the flange when I was assembling it and pushed the extension tube a tenth of a mm farther back.

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    I then used that marking distance (10.2mm) and cut 3.8mm off the end of the 14mm extension tube. This would let me butt the tube up right against the fatter part of the lens housing, making for a neat installation. I masked off the lens with cardboard and masking tape, sanded the lens housing where I was going to glue it, and cleaned it with 99% rubbing / isopropyl alcohol. Then with great trepidation, I used 2-part gel epoxy (with a thicker consistency than the typical 10-minute stuff to prevent runs) to glue the shortened extension ring to the lens. It worked really nicely, and I like that you can still see the Schneider markings and serial number.

    Since it is set to focus at infinity at a standard M42 flange distance, and uses a standard M42 screw, I can use the lens on any mirrorless system, and even on Canon DSLRs if I wanted to. I can even use it with my cheap 0.71x focal reducer to make it a 59mm/f1.4 (with good results).

    The Results

    Quite nice! The lens is clearly high quality. It's about as sharp as I have seen from a fast legacy lens, though it suffers from very significant lateral chromatic aberration, which is disappointing. The contrast is relatively low, but I actually see that as an advantage, especially since it doesn't have the same "glowiness" from spherical aberration that I have seen in a lot of fast old lenses.

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    With the helicoid, it can focus reasonably close (though certainly not macro magnifications), giving it absurdly shallow depth of field. Especially with no iris to stop down!

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    I took it for a bit of a photowalk one evening to try it out, and while I must admit I'm super self-conscious about street photography, it was fun. The GX7's tilt screen, great touch magnification and focus peaking came in handy.

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    None of the photos that resulted are art by any means, but they should give you a sense of what you can achieve with a converted Schneider like this, and are more interesting test subjects than book shelves, I hope! I have steadfastly resisted the temptation to monkey with the sliders - these are straight RAW conversions in Lightroom, so the contrast, colour, sharpness, and aberrations are undisguised.

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    The flare characteristics are extremely interesting, with a giant rainbow ring instead the typical ghosting across the frame. I'm going to have to experiment with this aspect more, and put it to some artistic use, since I find it quite striking.

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    Very nice detail across the frame when focussed at infinity.

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    When I have the opportunity to shoot some engaged human participants, I think it'll make a very nice lens for head and shoulders work, and maybe even full body environmental shots.

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    Really luscious bokeh up close, as you'd expect.

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    It reconciles itself pretty well in some situations where you'd expect really busy bokeh (I would have figured repetitive hard reflections would look nasty):

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    ...But not in all circumstances. The lattices and wires in the background here still show as somewhat unpleasant double-edges.

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    In general, it's about what you'd expect. A narrow field of view; lots of telephoto compression; tricky manual focus; good light gathering; and extremely shallow depth of field, whether you want it or not!

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    For under $100 and a couple hours of work, I'm pretty happy with the results. I don't know whether it will get a ton of use, but in the mean time it certainly scratches my itch for a long, fast lens to play with. I'm very curious to see how it will handle night shooting, and the kind of light that comes into play there.

    Hope this hasn't been too rambling, and that people can get something out of it, and perhaps even find the encouragement to do some interesting conversions themselves!
     
    Last edited: Jul 15, 2017
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  2. retiredfromlife

    retiredfromlife Mu-43 All-Pro

    May 15, 2016
    Sydney, Australia
    I have been going around the second hand shops looking for one of these type of lenses to give this a try, so far out of luck.
    Nice article to refer to later when / if I can obtain one.
     
  3. gnarlydog australia

    gnarlydog australia Mu-43 All-Pro Subscribing Member

    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    just when I thought I have enough projector lenses you bust out this one!
    I have often seen those gold Schneider lenses on evilBay but not many samples of images taken with those.
    And this lens seems to be above the average cheapo projection one and to me bokeh is very pleasant, double edges and all.
    I have little desire for creamy (for that I have the Pentacon 135mm f2.8) but I want texture, character.
    Not sure if you did (you don't say) but if you add a hood often those projector lenses become way more contrasty as the hood reduce the flare significantly.

    Your sample images are awesome, really, to the point to head to look online if I can see one for sale!
    Could you make this thread as "Showcase" in the adapted lenses Forum? it deserves it
     
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