View Full Version : Shutter Testing . . .Spot meter/Flash meter?

Drew Bedo
5-Dec-2010, 09:13
I know that this subject has been discussed often. Its important to all of us at one time or another.

I was reading a threads here and looking on *-bay and thinking . . .

would it be posible to use a spot meter or flash meter to get a relative indication of the consistancy (repetability) of a shutter at a set speed? If so, one could also check several shutters against each other at set speeds to see if one is slower or faster thab the other.

I havn't tried this yet, juat asking for your thoughts.

Nathan Potter
5-Dec-2010, 09:59
A spot meter measures intensity of light whereas a shutter delivers a dose of light (intensityXtime) which is milliwatts or joules in science terms. So you will need to separate shutter time from intensity using a timing device. A standard timing device is what is somewhat difficult.

The really accurate way is to use a storage oscilloscope with a calibrated time base and triggered with a fast photocell arrangement where the light passing thru the shutter can be recorded using the calibrated time base on the scope.

The audio technique has been discussed often here and will work decently.

Commercial testers are for for sale in various places.

A light meter could be used if it is equipped to independently measure intensity and dose. That is you will have to extract a time only function from the dose readout. There may be such meters around but I'm not familiar with such. Others here may be.

Nate Potter, Austin TX.

5-Dec-2010, 11:16
A TTL flash meter (Minolta FM III up with booster etc.) will do nicely for consistency tests at mid to fast speeds - simply set the meter to flash and use it with ambient light. Absolute values might be a bit off for times outside the 125-500ms range, but consistency can be checked with a very high degree of accuracy.