You know those little screws that everyone asks" What is this screw sticking out of the back of my lens and is it safe to remove?" What size are those and where can they be purchased? Alternately I would like to know a sure fire way to stop a lens rotating in the lens board. It's already over tightened, still spins. Have two Fujinon an one Nikkor lens and only one screw.
make a washer out of thin leather or rubber if the retaining ring doesn't screw down far enough to grip the board on it's own.
Two questions: One - do your lensboards actually have the recesses to accommodate those lock-screws? (as in Graphic lens boards?) And two - are your lens boards thick enough, and do they have appropriate diameter holes...to accommodate the diameters of the inner flanges of your retaining rings - while also being thicker than the depth of the inner flanges, to prevent these inner flanges from "bottoming out" on the rear surfaces of the shutters?
You can buy multi-size sets of tiny screws for eyeglasses on Amazon (I just did). I haven't tried fitting one into a lens, but I would be very surprised if there isn't one that would fit. If you take a lens with you and go to a friendly optician, you can probably find out the size and get some.
I'll try to check the size when I get home tonight.
Jeff
You can use a screw with a 'drum' shaped head. Two common types are filister head and socket head screws. The threads on the shutter are probably metric but there is no shame in re-tapping the holes to proper American size threads.
These are available from McMaster Carr https://www.mcmaster.com/products/screws/
The screws supplied with shutters look like custom screws - which are very common and made on a 'Swiss screw machine' - google for videos of these machines.
Darkroom Automation / Cleveland Engineering Design, LLC
f-Stop Timers & Enlarging meters http://www.darkroomautomation.com/da-main.htm
I think John hit on the issue: it sounds like your lens board is too thin. As someone else suggested, make a spacer so the retaining ring will actually tighten up. I would forget about the anti-rotation screw as a solution.
Keith Pitman
I'm using standard factory Toyo 110 boards for my 45A. I'd think it would work but I'll look into shimming it.Originally Posted by Keith Pitman
Great idea let me know if one of them fit.
Technically it's a stud not a screw which may help finding one. Tapping the hole for another thread is dicy with the shutter assembled. Blind holes require a bottoming tap and the skill to use one.
Tightening the lock ring should be enough. Most of my lenses don't have locating pins. I would cut shims if the lock ring doesn't tighten the lens.
Both the Copal 0 and Copal 1 use a 1.7mm diameter screw. The Seiko LS 26 (Copal 0 size) uses a 1.2mm diameter screw. The threads per inch isn't specified.
Neither of the two Copal 3 shutters that I have, have locating screw holes.
jeff
Posting Permissions
Reply With Quote
Bookmarks