Silver ringed Copal #3 UK CLA?

[BennehBoy]

I just learned the costly way that the copal 3 on a 165/8 SA I picked up has problems with the timings. A box of 8x10 160S came back from the lab with 5 sheets perfectly exposed, and 5 so underexposed there's barely a ghost of an image - all the underexposed sheets were shot on the shutter's slower timings.

After firing the shutter at each of the slower speeds it looks like the 1/4 speed actually fires faster (alarmingly so) than 1/8's - is this the handoff point between 2 timing mechanisms?

I guess I pretty much need to get this thing CLA'd, so has anyone any idea about where the best place to send this in the UK is, and an approximate price?

Thanks.

[gari beet]

Hi Bennehboy, I have used these guys in the past, great service.

http://www.bonwcameras.co.uk/

Gari

[Gene McCluney]

I wouldn't call 1/4 sec the "hand off" point. There is a little gear train inside that provides shutter closing delay. As you go slower in shutter speed this little gear train runs longer before it releases the shutter. There is a cam in the ring you turn to set shutter speed that allows a pin to swing (against spring pressure) further out thus giving the slow speed gear train more "run" before the shutter closes. At some point as you go to faster speeds the little gear train is compressed completely and does not become a factor, and the faster speeds are just goverened by spring pressure. It is probably just a cleaning issue. I clean my shutters myself as it is quite easy if you are the least bit technically inclined. The slow-speed geartrain is the first to show problems, in general from dirt and stuff that gets in from the air around us.

I should add that large mechanical shutters are not anywhere near as accurate as the electronically controlled shutters on small format cameras. While yours obviously has a problem, for critical work you should consider getting a 4x5 back for your camera and shooting a Fuji Instant film to check exposure. If you are shooting larger than 4x5, then of course you can't check composition because you can't see on the Instant Print all the field of view you are taking in, but you CAN determine exposure.

You can also get your repair person who does the CLA to measure all your shutter speeds and give you a little chart telling you "actual" speeds, which can be a great help when exposing color film, particularly transparencies.

[Roger Thoms]

I just go a shutter back from service and the sheet with the actual shutter speeds was quite informative. Recommend having the shutter speeds measured so you know what your working with.

Roger

[Nathan Potter]

What I want is for some genius to design or modify a film holder which then can be used as a shutter tester in the field. You simply slide in the holder with sensor and digital readout and check the shutter prior to taking the actual picture. Especially useful for very cold weather.

Nate Potter, Austin TX.

[BennehBoy]

Awaiting responses from a couple of places - thanks for the info.