Graflex.org

speedj · Joined: 08 Sep 2006 Posts: 11

Hi,

I have a Speed Graphic Anni and recently, while using the focal plane shutter, my exposures have come out overexposed. I use a light meter to make my exposures and I know that is correct because other cameras are properly exposed.

Is there a technique I can use to check if the shutter speeds are accurate?

jason

Dan Fromm · Joined: 14 May 2001 Posts: 2120 Location: New Jersey

When I got my Speed, I did the equivalent of exposing test strips, using Ektachrome.

glennfromwy · Joined: 29 Nov 2001 Posts: 903 Location: S.W. Wyoming

I've had pretty good luck using my Calumet shutter speed tester. It requires an opaque card with a 5/16" hole in it, placed over the opening in the camera back. It serves to exclude unwanted light. The ground glass focus panel must be removed for the test. I realize not many have one of these testers but it may give some ideas. My guess is that your shutter just needs to be lubed. Not hard to do and it should perk it right up.
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Glenn

"Wyoming - Where everybody is somebody else's weirdo"

troublemaker · Joined: 24 Nov 2003 Posts: 715 Location: So Cal

Glenn,
My Calumet digital tester just says (without lens) point probe towards light bulb and bring towards bulb until tester just starts running. Multiply the distance between probe and light by .71 and place film plane at this distance with the probe at the focal plane to test.
I tried it first on a Speed 23 that I thought to be fairly accurate and seemed to work quite well as suggested.
I really like this thing. Too bad they don't sell them any more.
Stephen

BetterSense · Joined: 17 Nov 2009 Posts: 18 Location: Dallas

Seriously, there's not much that can happen to a Speed Graphic focal plane shutter to change the speeds. The speeds are a function of the width of the slots, and the speed that they go past. The widths won't change, and the speed isn't adjustable (the spring tension has to be a certain amount to work). The governor for the intermediate speeds is non-adjustable.

If you are shooting transparency film and need to know what the speeds really are so that you can precisely calibrate your aperture/exposure, then use a shutter speed tester. But if you shoot negative film, it's pretty safe to say that if the shutter is *working*, the speeds are quite accurate.

Dan Fromm · Joined: 14 May 2001 Posts: 2120 Location: New Jersey

BS, I think you're mistaken. My little 2x3 Speed's FPS runs around half a stop slow according to a borrowed shutter speed tester. I haven't done it yet, but lubricating it may get the speeds up.

I have a little 2x3 RB Series B with an older style shutter -- six tension settings instead of two -- that is simply haywire and won't respond to retensioning. Changing slit width has the expected effect. Changing tension from 1 to 6 changes shutter speed by about 1/6 stop. Retensioning the spring shifts all speeds up (tighter) or down (less tight) and changes how well the shutter closes from "O" at tension 1.

BetterSense · Joined: 17 Nov 2009 Posts: 18 Location: Dallas

Not mistaken...I just consider a shutter within 1/2 stop to be functioning correctly. I doubt any of my shutters, leaf or otherwise, are truly +- 1/2 stop.

Dan Fromm · Joined: 14 May 2001 Posts: 2120 Location: New Jersey

Thing is, my little RB's shutter is a Graflex focal plane shutter and it isn't functioning properly. The speed difference between tension 1 and tension 6, for the same slit width, should be 1 stop, not 1/6 stop. Your "within 1/2 stop is good enough" rule doesn't fit it.

Come to think of it, it isn't that good a rule anyway. I have Compounds and Compurs and Copals and Supermatics that are a lot closer than 1/2 stop to nominal. I think you're accepting slop when you should hold out for a good meal.

45PSS · Posted: Tue Nov 17, 2009 8:01 pm Post subject:

http://www.hrtranslations.com/photo/shutter_v2/shutter2.html
http://photo.net/large-format-photography-forum/0044cW
http://download.cnet.com/1770-20_4-0.html?query=audacity&tag=srch%3Ba&searchtype=downloads&filterName=platform%3DWindows&filter=platform%3DWindows
Some simple, easy to build, shutter speed testers that are reported to work well and an excellent freeware audio program to run them with.

1/3 stop exposure difference is delectable in negatives or prints, shutter speeds should be within 1/3 stop of stated speed. I prefer 1/6 or less.
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