Shutter speeds on a Copal 1

**numnutz** · 21-Aug-2010, 08:06

I have purchased a shutter speed tester recently as I am trying to make a shutter similar to the one shown in this post:
http://www.largeformatphotography.in...ad.php?t=63707

I have noticed on testing one particular shutter, a Copal 1 SNo. 1561xx, that the top speeds are very slow, 1/400th sec is actually 1/200th sec and 1/200 is 1/172, the rest of the slower shutter speeds are within 5% of the indicated speed. I realise that mechanical shutters will vary and not be too accurate, but I always though that the faster speeds on mechanical shutters were more accurate than the slower. The fastest speed I have used so far on this shutter is around 1/125th second.

Should I worry and have an expensive CLA or just leave things as they are?

Thanks in advance for your input.

nn

**Gem Singer** · 21-Aug-2010, 08:23

If you are not using the 1/200sec. and 1/400 sec. speeds, and the slower speeds are accurate, leave things as they are.

If you are planning on using those faster speeds, it's CLA time.

**erie patsellis** · 21-Aug-2010, 10:09

1/172 is within Copal's spec of 1/3 stop, isn't it? As to the highest speed, I've never seen one more than a few years old that's even close, the -1 stop is about right, from my experience. Since most of my exposures tend to 1 sec. or longer, I don't worry about it.

**John Koehrer** · 21-Aug-2010, 10:22

Faster speeds are usually much slower than indicated and your values are typical of the beast. If you actually use faster speeds, just make note of the actual speeds to use them.
A CLA most times will not help you out, it might, but rarely. ISO tolerance on high speeds are in the +/- 50% range so your speeds are within range.