Inspired by a post on MU-43.com I've brought a 50mm f/1.2 projector lens & mounted it in an old helicoid. For the princely sum of $10 (+ postage) & a few hours in the workshop I now have a working f/1.2 frankenlens 1 by Mike Kanssen, on Flickr The rear of the lens tube had to be removed to get close enough to focus on mirrorless cameras, but the rear elements are well recessed so this wasn't a problem. The lens doesn't fit inside a normal M42 helicoid, but fitted in an old astronomy (T2) helicoid I've had for years (I brought it for £6 before M42 helicoids were readily available on e-bay). To get the lens far enough back in the helicoid I had to enlarge the opening (with a hole saw & finished with a file & sandpaper) & cut of the T2 thread at the base sticking a (£2) c-mount adapter in it's place. If I hadn't had the old helicoid available I'd have used a M52 one readily available on e-bay together with a stepping ring but that would have involed a longer wait... It's currently to bright to try outdoors, till I arrange some waterhouse stops or ND filters, but here's some quick examples of it's results: Timmy via frankenlens by Mike Kanssen, on Flickr Rufus via frankenlens by Mike Kanssen, on Flickr Cat shots being compulsory on social media!