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Computar 12.5mm 1.3 that almost fully covers a mft sensor.
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PostPosted: Mon Feb 03, 2014 10:06 am    Post subject: Computar 12.5mm 1.3 that almost fully covers a mft sensor. Reply with quote

picked this up at the market over the weekend for cheap, the only reason being because it was so fast, I lost my c Mount adaptor a while back for I just held the lens in front of the camera.

I was expecting to see a small image circle but to my surprise it covered most of the sensor, in fact if you put the aspect ratio to either 3:2 or 16:9 it covered the whole sensor with probably something similar to the 14mm 2.8 lens angle of view.

(I eventually figured out the the different aspect ratios does crop the sensor......silly me)

did a bit of research and it seems you get 2 different types of these lenses. one being quite common that has the writing on the front of the lens barrel and has 3 aperture blades and one that has the writing on the outside of the lens barrel with six aperture blades that forms a star iris at about F.4

the only reference I could find was this in the bay:

www.ebay.co.uk/itm/C-MOUNT-COMPUTAR-1-3-12-5mm-TV-LENS-MODIFIED-m4-3-G3-Super-16-Pentax-Q-/390658239610

I realise I'll probably have to shave some of its base off for it to reach infinity focus but just thought I'd share.

I'll order me a whole bunch of new adaptors and post some pics.


PostPosted: Sat Jun 21, 2014 3:34 am    Post subject: Reply with quote

Have you tried it yet.? I've thought about buying one. I do have the Computar 12.5 1.8 but that's a totally different lens.


PostPosted: Sat Jun 21, 2014 6:24 am    Post subject: Reply with quote

I have and its pretty cool:) I got a fotodiox adapter and it had to machine down quite a bit of the lens base for it to reach infinity.

not great for landscapes as it's not razor sharp but it does work nicely for closer shots anything closer than 5-6 feet and the closer you get the more of a fisheye effect appears, so now its become my cheap fisheye lens Very Happy

can't find the thread now but apparently there is a guy who is able to tweak the lens itself so it covers the full sensor on MFT.

it is fast though works nicely in low light, much better than my 1.4 lenses but I also suspect this is due to its wide angle so you don't really pick up on camera shake as much.

I'd like to see what this lens can do in more capable hands than mine so if you can find one at a good price I'd say buy it as it has good qualities.


PostPosted: Mon Jun 23, 2014 8:30 am    Post subject: Reply with quote

Thanks. I will try to find a copy. My Computar 12.5 1.8 will also need quite a bit of machining to work.


PostPosted: Mon Jun 23, 2014 10:36 am    Post subject: Reply with quote

ah I just realised you use the j1, you'll get full coverage with either the 3 or 6 blade version. the 3 blade version gives interesting highlight accents from what I've seen.


PostPosted: Tue Jul 01, 2014 1:50 pm    Post subject: Reply with quote

I picked up a few of these with the intention of modification. They're VERY simple and easy to open up. My intention was to increase sensor coverage, but I found changes seemed to increase field curvature. It got much softer. Now I'm looking at reversing some of those changes so I can add it to my camera bag.


PostPosted: Mon Aug 18, 2014 3:54 pm    Post subject: Reply with quote

I posted a quick and easy infinity focus fix for BMPCC and the 12.5mm f/1.3 lens here on the forum (which I think I accidentally posted in the wrong thread, although it may be accurate there as well) ... http://forum.mflenses.com/computar-25mm-f-1-3-t35985,highlight,+computar++12++5mm,start,15.html