PDA

View Full Version : How to test Graflex FP shutter



Dan Fromm
18-Jul-2017, 04:00
Calumet shutter tester will do it.

To minimize film used, do the equivalent of printing a test strip.

Jim Galli
19-Jul-2017, 16:53
Calumet shutter tester will do it.

To minimize film used, do the equivalent of printing a test strip.

Not so easy Dan. The focal plane actually takes something like 1/12th second to travel from top to bottom. The exposure on the large area happens as the open slit travels past a little at a time. Different width slits offer different exposure as well as different spring pressures. It works more like a movie camera shutter than our usual leaf shutters. Width of opening and speed. But movie cameras are easy to calculate since they travel in a circle and we divide degree of opening into 360 times rotation. On the focal plane at say 1/8th inch slit, the top of the film gets it's exposure as the slit moves by and the bottom may get it's a 12th second later. Equivalent time is what would have to be calculated. Smarter guys than me that worked at Graphlex figured it all out. Lube the axles and limber it up and trust what those guys inscribed on the camera. I've had good success doing that.

Dan Fromm
19-Jul-2017, 16:59
Jimbo, the test strip has to be shot at each shutter speed (slit width/tension combination). I did this using E6 film with my 2x3 Pacemaker Speed Graphic after it arrived. I was lucky, it shutter is close enough.

You can't count on Graflex' focal plane shutters to be on speed. My infernal little 2x3 Graflex RB Ser. B's shutter speeds aren't affected by spring tension. The wretched thing has four (4) shutter speeds, none as indicated by the plate. I think it needs a new mainspring or whatever its called.

Cheers,

Dan

BrianShaw
19-Jul-2017, 19:00
Listen to Dan. He's correct. He know it already, though...

But I did what Jim Gallo sugggests on one camera and it worked fine too.

Jim Jones
20-Jul-2017, 06:13
To check for even shutter travel, shoot a negative of a plain white or grey subject at the lowest shutter tension and narrowest slit. The exposure and developing should be for a medium density negative. Exposure should appear even from top to bottom. You can also measure the exposure in the focal plane at several points from top to bottom. Any shutter tester that measures actual light should work for this. An oscilloscope and a fast-responding light sensor are useful for analyzing shutter function.

jnanian
20-Jul-2017, 13:32
i used something like a calumet tester and it might not have been perfectly accurate but it is "good enough"
i also exposed 2 sheets of film-- 1 with the fp shutter at x shutter speed and one with a "accurate" attached to a lens
its ez to see if it is good enough ... even if it is off a little, you know to not worry about it...

pierre506
21-Jul-2017, 16:46
I'd like to calibrate the focal-plane shutter on my new-to-me Anniversary Speed Graphic. Without using up a lot of film...
It does seem to work properly and I can see no pinholes.
Ideas, anyone?


Easy works and economic (no cost)way(This way can also test other normal shutters):

1
Putting a digital SLR camera(Nikon, Canon, etc.) behind your Speed (or Graflex SLR).
Closer is better.
You must need two tripods.
Focusing.
You should put a darkcloth between your Speed camera and the digital to avoid light leakage.

2
Putting your Speed curtain shutter on B, mirror up
Shoot different shutter speeds (1/1000,1/750,1/500...) by your digital
camera.

Putting your digital camera on B
Shoot different shutter speeds (1/1000,1/750,1/500...) by your Speed
camera.

3
Compared all the pictures' histograms.

Then you knew the results.
a.
You need to tighten or loosen your curtain shutter's spring if the histogram results displacement.

b.
Or you couldn't make any adjustment to the spring.
But you can make a new speeds scutcheon.

Enjoy it.

通过我的 VIE-AL10 上的 Tapatalk发言

jim10219
24-Jul-2017, 08:47
Easy works and economic (no cost)way(This way can also test other normal shutters):

1
Putting a digital SLR camera(Nikon, Canon, etc.) behind your Speed (or Graflex SLR).
Closer is better.
You must need two tripods.
Focusing.
You should put a darkcloth between your Speed camera and the digital to avoid light leakage.

2
Putting your Speed curtain shutter on B, mirror up
Shoot different shutter speeds (1/1000,1/750,1/500...) by your digital
camera.

Putting your digital camera on B
Shoot different shutter speeds (1/1000,1/750,1/500...) by your Speed
camera.

3
Compared all the pictures' histograms.

Then you knew the results.
a.
You need to tighten or loosen your curtain shutter's spring if the histogram results displacement.

b.
Or you couldn't make any adjustment to the spring.
But you can make a new speeds scutcheon.

Enjoy it.

通过我的 VIE-AL10 上的 Tapatalk发言

That's pretty close to what I did. I ran my DSLR backwards through the Graflex with the film holder and ground glass removed from the back, so the lens was pointing backwards through the hole on the lens board. Then I shot a scene with the camera set to a 15 second exposure (long enough to get everything set up without being too long requiring me to wait) and just used the focal plane shutter on the Graflex to control the light. If you need to, you can throw your dark cloth over the DSLR and lens board to keep out any stray light that might interfere with your shot. Then I shot the same scene with the same camera settings, but instead of setting the DSLR to 15 seconds, I set it to whatever speed the shutter on the Graflex focal plane was set to. Then I compared the histograms of the two, adjust the spring, and repeat. It didn't take long to get all of the speeds pretty accurate. Once you get one dialed in, the rest usually fall in line so long as shutter is operating properly. Real world tests with film confirm that this method works really well (at least for me).

Jim Galli
24-Jul-2017, 08:57
This thread has gone from bizarre to rediculous. If you have a 4X5 inch film area 1 or 2 millimeters away from a curtain with an 1/8th inch slit that passes over that surface, then most of the image plain is dark most of the time the curtain is in motion. Tell me how a Nikon or a shutter speed tester is going to give you a reliable answer. I've been doing my best to keep quiet; but it's getting pretty deep out there.

pierre506
24-Jul-2017, 16:50
A practice may be worth thousands of words~

通过我的 MHA-AL00 上的 Tapatalk发言

Oren Grad
1-Aug-2017, 19:17
Replies all moved to their own thread so that the spam that was the original post could be nuked without destroying the rest of the discussion.