Shutter Speed Testing (was Re: [LargeFormat] rest)

[Clive Warren]

At 09:18 30/01/01 +0000, philip Lambert wrote:
>Is there an easy way of checking the accuracy of shutter speeds? I have
>several old lenses whose shutters seem to run slower than a new shutter.
>Philip
>----- Original Message -----
>big snippety snip


Yep!

Calumet make a digital shutter tester which is relatively inexpensive and 
does the job well.  I have used mine for a couple of years and am very 
happy with it.  Having fired the shutter a couple of times,  I then use a 
bright light source behind the lens with the shutter tester held such that 
the light sensitive cell is placed close to the centre of the rear element. 
The shutter is then fired about three times and an average reading of the 
shutter speed is used as the reference point for that shutter.

Writing the information down and placing the note in the bag with the lens 
is a good idea for use in the field.  Cold temperatures will have an effect 
on an old lens, particularly if it has not had a CLA recently.  A shutter 
that seems to behave well in the warmth of your living room will sometimes 
stick open in low temperatures!

Most of the older shutters sitting around here fire at all speeds quite 
happily after a CLA, but the top speed(s) are usually about double the 
stated opening durations.......

There is one Ektar in a Compur that I am very reluctant to clean up as it 
seems to run at modern shutter speeds even though marked up for the older 
speed range......  All down to old gummed up oil :-)

All the best,
                 Clive   http://www.f32.net
                         Large Format Travel and Stock Photography