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05-02-2009, 07:18 AM   #16
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conversion of the 85mm f/1.2 lens is complete, was it worth it?...you be the judge.

personally I think this lens is just a tad flat in terms of colour rendition. I think the SSC version would have been better. it's flare tolerance isn't anything to write home about either....I wonder if I can find the hood for it...


Last edited by Digitalis; 06-20-2009 at 06:51 AM.
05-02-2009, 10:05 AM   #17
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Plastic filler (as used by model builders), certain "wood dough" pastes, and J B Weld (metal filled) epoxy are easy to work with to fill holes and fix light leaks. J B Weld can even be used to sculpt / re-build damaged parts.

H2
05-02-2009, 11:10 AM   #18
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Sears lens conversions

Yesterday I converted a Minolta mount Sears 28/2.8 Auto Macro lens to P/K functionality.

Those made by (I believe) Mamiya-Sekor are pretty straight forward conversions and worth the effort. From 28-135mm, those lenses with four equally spaced mounting screws on the bayonet fitting are almost identical inside and the aperture mechanism is very easy to understand and switch to P/K type-M (no AE) operation using cannibalized P/K mounts. Focal plane distance maintains infinity focus without adjustments in this case.

In this particular case, I used a replacement P-K bayonet fitting from a defunct Sears 135/2.8 and the only work needed was to disconnect the auto aperture spring(s) so it acts like an SMC-M and remove one flange that interfered with mounting. Keep the four mount screws with their own body as the thread pitch is sometimes different - 0-72 or 0-80.

MD > P/K Sears 28/2.8 Macro - *istDS ISO 1600 f8 @ 1/45 sec 1:4 ratio
Total cost $18 + 1 hr 15 min

H2
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05-02-2009, 03:10 PM   #19
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I bought a FD mount 24mm F2 with a non-working aperture, should get it next week. I'd love to be able to adapt this lens to a PK lens with manual stop-down aperture, I think a fast wide angle like this will be a lot more challenging to convert than a tele lens, there's just much less room to work with.

05-02-2009, 05:54 PM   #20
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I will be surprised if you can get it to focus at infinity, wide angles have a reduced scope for focus adjustment when compared to fast telephoto primes...canon also made a 24mm f/1.4L. I have the current incarnation and I use it on my 1DMKIII it's not that great wide open on such a high resolution camera,but it does wonders when it's stopped down a bit.
05-02-2009, 10:58 PM   #21
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Yeah I know it's a long shot to get it to work, I don't even know if I'm going to try it as I've never done any serious mods to lenses before and don't have any real experience in taking lenses apart. It was cheap though, so I figured I'd get it. I do have a friend with a lathe, that could be helpful for this or another lens. It's likely that it's technically possible, but will probably be very difficult compared to a tele lens and require more complicated modifying.
05-13-2009, 03:29 AM   #22
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Hi Digitalis,
congrats for the conversion!

I think the pics show the potential and here's my take about it. I recently used an old CZJ Biotar and it showed likewise behaviour. I put a warm UV-filter (1B) on it and was careful with the hood and/or additional shading by hand. There was already much improved colors and brilliance. Then, the pics could be unsharp-masked quite a long ways - shows good resolution but low out-of-the box contrast imo. The key was not to underexpose.

Last, please tell me if you are getting full open infinity with your setup.

Thanks for sharing your conversion story,
Georg (the other)
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