MattNov 12

A bit of a fediverse hive mind request.

I've a PB mount Pentacon 50mm f/1.8 lens that came with a Praktica BMS but it's not sending the selected aperture via the 3 electrical contacts. I'm finding it hard to find a guide for stripping the lens down as most are for the M42 version, any help in finding this info would be most helpful.

EDIT: I found this video and although fiddly looks like it's just a potentiometer https://www.youtube.com/watch?v=TrpvTcZcgJI

#praktica #filmphotography

Show threadRamón de la Rosa Steinz
@matt303 I have a BX20s and some PB lenses. Some years ago I built a custom three-contact add-on for an adapter ring. For the 50 mm lens, you don't need to disassemble the entire lens (more risk to introduce dirt). Just remove the rear black plastic cover to discover four screws: you can use your fingernail. Remove the screws and you should reach the carbon plate with the cursor. I would apply a contact cleaner (a spray you can buy in an electronics shop), being careful not to spray the lens.
Nov 12 at 8:55pmWeb
Show threadMattNov 12

@ramon_ea1gth I got it to bits and unfortunately the issue is that the bit of clear plastic that holds the three contacts has shattered where it attaches to the inner ring with a screw, allowing the whole set to move and not make contact with the camera. I think there's a fix I can do if I can 3D print a small enough part to hold it in place.

I buy these cheap charity shop finds to keep me busy and I'm getting my £12 worth out of this camera bag of stuff 😉

Show threadRamón de la Rosa SteinzNov 12
@matt303 Yep, brittle old plastics are a problem. Good luck with the restoration! Sometimes I'm able to rebuild some tiny pieces by preparing an improvised mould and refilling the cracks with two-components epoxy glue. Also, about the 6V battery for the camera, it can be also interesting to pile-up 4 cheap alkaline 1.5V coin cells: there is a cell size/thickness that fits. Have fun!