View Full Version : Calibrating shutter speed

11-Sep-2009, 19:49
I had a talk with someone today about camera shutter speed calibration at the college I go to. They told me that they have to take their camera a 35mm manual film camera to get the shutter speed calibrated. they are taking what is called a zone class as in the zone system. So that a 60th is a 60th and so on. I have had my LF lenses measured to get the true shutter speed and my 35mm camera also. I have never heard where someone gets there shutterspeeds calibrated so that they are what they say they are. Can this really be done. They also claim that this has to be done to properly do the tests for getting your personal iso numbers and development times which I dont think is correct.

sun of sand
11-Sep-2009, 20:26
if your 1/60th is 1/120 it will mess up results
If you know what your speeds are it doesnt matter if they match the engraved speeds or not

I'd bet shutter speeds are fine for use unless obviously off
Don't think you're going to say 1/5 of a stop ruined your negative
Do any LF lenses have click fstops? what if you were to misalign the arrow
the horror

35mm doesn't seem to lend itself to zone development so it seems more like a 1/2 zone class

11-Sep-2009, 20:38
I agree about the 35mm for zone seems kind of silly to me. The whole point to zone is the ability to expose and develop film on an inividual basis. I also agree about you just need to know what the actual speed is so you can make and accurate exposure. Thanks for your response.

12-Sep-2009, 08:26
The Shutter speed is not variable like aperture is. a 1/30 is a 1/30 however you can do f81/2 by approximation for example. A good cleaning (CLA) will do wonders for slow shutters. If its one of the modern shutters cleaning is probably what is needed for slow shutters. If it needs repairs then the shutter would be re-calibrated when repaired, make sure to include this in your repair order. Being off 1/5 of a stop for most occasions wont matter much. If you are over or under exposed this small amount of a stop it wont make much difference for negative density or detail.

As to the 35mm and zone system it works fine and you carry lots of short rolls of film. Yes its a pain and you risk not having a back up negative whose purpose is to shorten or lengthen development time to change contrast on the first shot. You find this out only after printing the first negative! Roll film and zone exposure is inconvenient not impossible! And yes you cant get big enlargements with 35 mm film whats important is taking good images.

12-Sep-2009, 08:33
The Syncro-Compur shop manual gives like a 10% range for many of the speeds. The speeds CAN be adjusted. Realize that the speed changes at different apertures (look up "leaf shutter efficiency"). So plus-or-minus 10% will be fine.

Of course if you are shooting B&W negative film the latitude is 6 stops (Average scene brightness range minus the films dynamic range). Of course if you are shooting at "ISO speed" all the latitude is for overexposure and, by definition, almost no underexposure latitude.