My pancake is thinner than your pancake

Started Feb 12, 2012 | Discussions thread
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mauthbaux
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My pancake is thinner than your pancake
Feb 12, 2012

A few months ago, I caught the vintage-glass-collecting bug. One of the lenses I picked up was a 28mm f/2.8 on a cannon mount. It was listed under the "for parts or not working" category, which usually means that either the seller doesn't have a camera to test it on, or the autofocus isn't working (neither of which is a problem for use on the NEX). In this case, the lens was hosed. The glass looked a little foggy, and the aperture blades refused to move. I disassembled it and found extensive rusting, sand, and etching on the interior elements that couldn't be removed. I was only out about $15, so it wasn't too disappointing.

Well, after seeing so many complaints about a lack of pancake lenses for the NEX, I decided there was nothing to lose, and I embarked on a little project. I took a NEX body cap, and drilled a hole in the center of it. I then checked the focal distances on the individual elements from the old lens (lamp at one corner of a dark room, stand at the opposite side and see how far from the wall you have to hold the element to get it to focus). I picked the two elements with the shortest distances. I then experimented with the lenses to see which arrangement and orientation would give me the sharpest image. The way to do this was with the camera pointed at the floor, with one piece of glass sitting over the hole in the body cap, and the other lens held against the other side of the hole. Once I found a combination that worked, I fixed the lenses in position using some silicon sealant (the kind you'd use for aquariums).

After letting the sealant cure for a couple hours, it was time for a bit of shooting.

The above image is an OOC jpg with no post-processing. It's definitely not that sharp, and the contrast is quite low, but it has a lot of character. I do like the little halos around the bright spots, and the blurring towards the edges of the frame. If I had to guess, I'd say it's slightly narrower than the native SEL16F28 lens, but significantly brighter. Best part is that it only sticks out about 9mm from the mount, weighs almost nothing, and material costs were negligible.

disclaimer: I'm a total amateur at photography and know nothing about lens design or optics. If I had to do it again, I'd probably make the aperture a little smaller to help with DOF and blooming, and probably experiment with some spacers so as to not be constrained by the dimensions of the body cap.

Anyway, thought I'd share my silly little project with everyone on the forum here. Thanks for reading!

 mauthbaux's gear list:mauthbaux's gear list
Sony Alpha NEX-3 Sony Alpha NEX-6 Nikon AF Nikkor 50mm f/1.8D Sony E 18-55mm F3.5-5.6 OSS Sony E 16mm F2.8 Pancake +14 more
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