Speed Graphic shutter curtain travel timegreenspun.com : LUSENET : Large format photography : One Thread
Does anybody know the length of time it takes the focal curtain to travel across the image in a Speed Graphic? If I set my time at 1/1000, what is the length of time that will elapse from the moment the curtain slot leaves the top of the camera to the moment it closes completely at the bottom? I am trying to get aerial images as sharp as possible and I am wondering if a Speed Graphic at 1/1000 will produce a sharper image than a lens at 1/500 while in a tiny airplane travelling 100 mph and shaking all over the place. But perhaps the lens (which shoots no faster than 1/500) would provide the sharper image, as the shutter curtain will take some time to travel the whole distance and in that time my camera will be in a (perhaps significantly) new position relative to the subject. Earlier shots made with the lens shutter were not all that great, which is why the musing about a speed graphic. I cannot afford a new lens with a shutter speed of 1/1000.
-- Erik Ryberg (Ryberg@seanet.com), August 13, 1998
If you're truly getting 1/1000 sec from the focal plane shutter, you will see subject (or camera) motion as if you were exposing at 1/1000. What you may see due to the slow shutter curtain travel time is subject distortion. Objects may be elongated or tilted by the effect of the moving shutter slit and the moving camera.
I saw an article in a photo magazine a few years ago. A photographer was shooting other navy jets from the cockpit of a jet fighter. He used the focal plane shutter on a Speed.
I've never used the focal plane shutter on my Speed, but I would be really surprised if it's faster than 1/15th or so.
Don't forget that if you have the lens stopped down very far, 1/500 on a leaf shutter is actually open longer than 1/500 sec. Both for exposure calculation and motion blur effects.
-- mike rosenlof (firstname.lastname@example.org), August 13, 1998.
The focal plane shutter on my SG seems quite slow, compared to 35mm cameras. I would probably trust the leaf shutter more. The speed of the plane is relative. If you are some distance from the ground (subject), then the airplane speed may have little effect.
-- Ron Shaw (email@example.com), August 13, 1998.
On Anniversary and older SGs, the shutter curtain covers the film at between 1/10 and 1/40 of a second depending on shutter tension. I got a used 2x3 SG for aerial shoots, since the 1/500 setting on most shutters is more like 1/250 in real life, and I was getting noticible camera blur with a Crown graphic. The faster focal plane shutter is indeed an improvement.
-- John Lehman (firstname.lastname@example.org), August 13, 1998.