Crown Graphic Shutter Speeds

pevelg

pevelg

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I acquired a Crown Graphic camera, pretty good condition, about a month or so ago. I have been slow in getting full tests done on the camera. My first order of business was acquiring some Polaroid 4x5 sheets to run my tests. I ordered a bunch, mainly type 55, ISO 50. In almost all situations, I noticed that I had to adjust the aperture by about 1 to 2 stops to get a good photo. The majority of the time the shots were over exposed. There are thus two things that I figured were the problem. A., the Polaroid film needed a longer developing time, but I figure this would cause an even more overly exposed photo. B., the shutter speeds are somewhat slow. I took a recorder and recorded the sound of the shutter as it fired. The problem with this test was that the sound capture included the sound of the shutter mechanism starting to open and also closing, thus making the total length of shutter sound not coincide with the length of actual exposure. My next method of testing was to put a flashlight behind the ground glass, shinning at the lens. Thus, when the shutter opens, the light is displayed on the wall, indicating length of exposure. I borrowed my sisters camera which comes with movie mode. Thus, in a dark room, I set up her camera and started testing all the shutter speeds. Now, the limitation in this test is that the camera is limited to 30 frames per second. So, technically, this test can only be accurate up to only about 1/30 of a second shutter speed, or in regards to my camera, to 1/25 of a second. Anyways, here are my results, indicating the number of frames that show light on the wall.

1 sec shutter speed = 35 frames recorded at 30 fps
1/2 shutter speed = 16 frames recorded at 30 fps
1/5 shutter speed = 8 frames recorded at 30 fps
1/10 shutter speed = 4 frames recorded at 30 fps
1/25 shutter speed = 2 frames recorded at 30 fps

On initial review, it is visible that shutter is a little slow, with it taking around 1.166 seconds for the 1 sec shutter speed. Of course, at this slow of a speed, the difference does not make that much of an issue. At 1/2 shutter speed, it is almost spot on. Once we hit 1/5 and 1/10, the difference will become more noticeable, 0.266 seconds instead of 0.2 and 0.133 instead of 0.1 From this simple study, I would say that the shutter is about 1/2 stop too slow when considering faster speeds.

This again does not explain the reason my photos are overexposed by about 2 stops. Perhaps the aperture blades are not calibrated correctly? Anyways, I will be getting my first sheet slide and negative film this Monday. Do I start shooting at standard exposure or do I go ahead a compensate the 1~2 stops? I really can't wait to shoot some slide film, but it is just too expensive for such tests, especially if the problem is just the expired Polaroid film. Anyways, what is the advice from our dear forum readers? 🙂
 
Ok... I had purchased the quickload slide film and some B&W regular 4x5 sheet film. I have about 4 holders, so I will try to get at least 8 shots on my first shoot. Should I do all tests at one speed, and if just one speed, which should it be? I have been using my tripod the majority of the time with this camera, though I might use it hand held sometimes. Actually, I will test two speeds, four trials per shot. My plan is starting with proper exposure, then +/- one stop. Should the forth shot be 2 stops over or under? I will most likely test shutter speed 1/50 and one other. What should it be? My slide film will be ISO 50 and B&W film is ISO 100.
 
There are numerous film speed tests on the internet. These tests take all variables into account. Quick. Easy.

Carol Miller at Flutot's Camera Repair in California can make your shutter work well. She will give you a written list of what your speeds actually are.

Where did you find Polaroid Type 55? Fuji makes an instant print material that many use for exposure verification. You will need a different holder.

Good luck.
 
There are numerous film speed tests on the internet. These tests take all variables into account. Quick. Easy.
Click to expand...

Do you have a link? I found two tests, one you count lines on a tv and the other is similar to my method above. Since I don't have a tv, I can't do that test. As Richard has stated, the shutter speed is not off by that much, maybe a 1/2 stop at most. I can easily compensate for this, so no need for a CLA as the shutter works fine otherwise. I got the type 55 film off eBay, and all are expired. I've managed to get good shots, but I had to compensate about 1 or 2 stops to get proper exposure. I suppose that part of the problem is that since it is expired film, I need to be either developing the film longer or maybe shorter. I developed them according to the printed instructions. Anyways, tomorrow I get my negative film and I will load my holders. This will be a first for me, and I have no red light, so the pics will likely have prints and smudges on them, but that should be ok for testing. I will post some results if I have any problem.
 
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When I got my Crown Graphic the shutter was sluggish and actually hanging up at one second and also a half.

I removed and dismantled it and soaked it in lighter fluid for a while then carefully applied a little light oil to the parts that needed it with a fine syringe and reassembled it ... the aperture blades were a little tricky to reassemble but it's been fine since.

As Richard said though no old shutter will be totally accurate and it was probably no more accurate when it was new. Go easy on the lube though ... the first time I cleaned and re-lubed mine I got a little carried away with the oil and in the heat one day when shooting outside it actually sprayed a little semi vapourised oil into the lens ... I finished up having to strip the whole thing again!!
 
A word about the focal plane shutter on Speed Graphics. They can often be found very inexpensively. It is a lot different than the ones in a 35mm or 120 camera. The small cameras that we used have two seperate curtains on seperate sets of rollers. As the curtains move across the film they speed up a bit. The two sets of rollers are designed to make the slit between the curtains get wider as it moves across the film to keep the exposure the same over the length of the negative.

The Speed Graphic has a variable tension control with numbers 1 through 6 and just a single l-o-n-g curtain with four fixed curtain apertures, A,B,C, and D. A setting of 1A gives you 1/10 of a second while 6D gives you 1/1000 second. A little metal plate on the camera tells you the shutter speeds for all the possible combinations, all 24 of them. There's no way for the slits to open wider as they move across the negative so with the narrower slits the negative density varies a bit over the length of the negative.

Keep in mind that Graflex stopped making focal plane shutter "Speed" Graphics in the early 1960's, a decade or more before they stopped making Crown Graphics. With either model it was more likely to be used with the "front" shutter, a Compur, Rapax, or Kodak Supermatic between the lens leaf shutter.

There's a good chance that the focal plane shutter hasn't been used in fifty years or more, with the lubricant long ago dried up or gunked up. There's also a chance that it was stored for all those years with the shutter set at maximum tension, and the spring will be about shot.

I'm writing all of this because these days not many photographers are familiar with press cameras and might not realize that there is the rear shutter as well as the front shutter in some of them. Plenty of film was not exposed because the photographer failed to check and make sure that the shutter not in use was in the "T" (time exposure) position.
 
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I finally got fed up w/ under and over exposed photos and bought myself a shutter tester on fleabay from lurchrider. It costs $35.95 and will test up to 1/500. It's very accurate and very reasonably priced. Took a while to figure out how to read the graph on audacity (which is the free audio program that it uses) but it's second nature now. I tested it against my Leica R5 which has a very accurate meter and shutter and it checked out fine. The best 36 bucks I ever spent. No more guessing . I'm in the process of testing all my folders against it now and writing out the actual shutter times. A big help!

One thing I should mention is that I had a Rolleiflex that was underexposing. I tested the shutter speeds, then fired the shutter about 20 times on each speed and retested them. They were much better after the exercise. It may be that the shutter on your camera just needs to be exercised a bit, but I would still buy a tester to know for sure. And ix-nay on the Polaroid film. Get yourself a few proper film holders and load them w/ some good B&W film AFTER you know how the shutter is running. Br prepared to marvel at the excellent photos these cameras can produce.
 
I should have asked earlier:

What lens+shutter do you have on your Crown Graphic? Give the shutter a good exercising. Fire it 20 times on each speed sounds good. Then run a proper film speed (exposure index) test with the film and developer you plan to use for a long time. One trait of most large format users: 1 or maybe 2 films (slow & fast) and 1 developer. That's all.
 
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