Slide holding for Scanning - Ohnar and Other Options

D Cox wrote:

A BPM bellows is a very good thing to have, especially if you can build up a collection of the various lens and camera mounts.

Don't tempt me! There is an appeal to collecting more adapters but at the moment I have the ones I need. I actually bought two sets of bellows - the first was at what I thought was a fair price and came with the M42 lens and camera adapters. Before that one arrived another one came up on eBay for an even more reasonable price with Minolta MD adapters (I have several MD lenses) so I bought that one too. When it arrived it also had an M39 lens adapter. Happy days!

I find the M39 Leica thread ones (both male and female) the most useful. An M39 adapter on the camera is the shortest and helps you to get infinity focus. At the front end, an M39 ring accepts enlarger lenses.

I'm using an M42 adapter on the camera. The BPM M42 adapter is pretty thin when you unscrew the bit with the shutter cable (for stopping down maybe??). I started out using my existing M42 to EF adapter that I use for my telescope. This adds about 11mm. I've now bought a thinner one which adds just 0.8mm.

IIRC the 'correct' distance to add for EF to M42 should be a tad over 1mm, not that it matters when there is a bellows adding a lot more.

One thing did really puzzle me... with the 11mm long EF adapter I found that the focus on the Ohnar duplicator wasn't quite right. I didn't find this too surprising but I expected that fitting one closer to the correct size for M42 would bring it into better focus but actually it became much worse. Not a big worry since I'm not using the Ohnar optics but very puzzling anyway.