Graflex.org

[Jim23]

I'm going to shoot some color transparency film (Ektachrome 64 daylight) in one of my 4x5 Graphics (daylight exposures) and have a choice of camera/lens/shutter combinations. Shots will be taken with the shutter between 1/30 sec. and 1/400 (500) sec in daylight (not flash). Which shutter is the most accurate in terms of exposure(assume that each is properly C/L/A'd)!

Speed Graphic Focal Plane (Pacemaker 45)
1/30 - 1/1000
Speed Graphic Front Shutter (Graphex Pacemaker 45) 1-1/400
Crown Graphic Leaf Shutter (Compur MXCRO?)
1 - 1/500

All of my work in the past has been B&W and exposure has not been that critical.....

[extraparts]

No one else has answered so I guess I will, however, it reminds me of the cartoon showing the police kicking in the door guns drawn and shouting at the man in the room:"Put that can opener down and step away from that can of worms".

I have read that even new, shutters may be as much as 30% off. I built a tester and found that to be true.

Furthar, with the leaf shutters, there are groups of speeds. As you move from slow speeds to faster speeds you shift gear delay assemblies out. Typically 1 sec to 1/25 is one group, 1/50 to 1/250 is another group, and 1/400 or 1/500 is obtained by enguaging a extra spring. Most people will tell you that the very high speeds are usually slow.

This means that a leaf shutter can be accurate in one group and off in another.

Furthar they can be different at different temperatures and many photographers get in the habit of triggering the shutter several times before making the actual exposure.

Furthar, leaf shutters at have different effective shutter speeds at different F stops. This is because it takes longer to fully open and fully close at say F4 than it does at f22. This is only a problem at the higher speeds where the time it takes the shutter to open and close is a large percentage of the overall exposure time. Most good photography text books have charts for correction.

With focal plane shutters on Graflex you have a combination of spring tension and slot width which is a whole different nest of snakes.

There are shutter testers which can be purchased quite cheaply. About $100 or you can make your own from plans on the internet.

I don't think anyone can say with any certainty which of your three shutters is most likely to be the most accurate.

If you are going to do a lot of flash, you might want to pick your favorite lens and send it in for a CLA, then you can use the "known good" to make test exposures with the other two. I usually do this on one sheet of film to minimize variables. You can pull the dark slide half way out, and make the first exposure and then go into the dark room flip the film and do it again on the other side. Or you can make a special dark slide to do the same thing.

Hope this either helps or stimulates other answers.

Neal

[Dan Fromm]