Calumet Digital Shutter Tester

[WAn]

How does the Tester work, what is its principle of operation? Does it

detect a first sudden change in illumination as a start moment and

another change as end moment? Does it just count the time elapsed

between these two moments or does it measure the actually accumulated

amount of light between the moments?

 

I assume the tester must have a probe that should be positioned

somewhere in focal plane, -- correct?

 

How convenient is it? E.g. can it be used in photo shop before

purchasing lens/camera?

 

What is the precision of the tester?

 

Thanks in advance!

[dhananjay_n]

Yes, the tester is pretty convenient and can be tested at a shop. To operate, place the shutter above the tester, such that the shadow of the shutter falls over the tester. Place a bright light above the shutter. When the tester is switched on and the shutter is fired, the bright light will hit the sensor of the tester and it starts keeping time. When the shutter closes, it stops and displays the elapsed time. (Note: it does not measure illuminance, only the time between opening and closing). The tester does not need to be positioned in the focal plane, just behind the shutter, so that light hits the cell and turns it on. The tester seems more than precise enough for my needs. It returns decimal values e.g., 1.1 secs or 0.65 secs. There is a conversion chart on the tester for the more common fractional values e.g., 1/15 sec etc. In my opinion, the single greatest use of this tester is to test for reliability i.e., repeatability of the shutters. Take 5 or more readings at each shutter speed, ideally cycling through all the shutter speeds (i.e., cycle through the speeds 5 times). Hope this helps. Cheers, DJ

[ken_lee11]

For what it's worth, I found all my modern shutters to be quite close to their ideal speed. Even my 50-year-old Agfa medium format folding cameras were quite impressive. The money spent was worth the peace of mind I got. It is certainly small enough to carry to a store.