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Erik Ryberg
13-Aug-1998, 17:14
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 o f time that will elapse from the moment the curtain slot leaves the top of the c amera to the moment it closes completely at the bottom? I am trying to get aeri al images as sharp as possible and I am wondering if a Speed Graphic at 1/1000 w ill produce a sharper image than a lens at 1/500 while in a tiny airplane travel ling 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 w ill 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 s hots 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 1/10 00.

mike rosenlof
13-Aug-1998, 17:43
If you're truly getting 1/1000 sec from the focal plane shutter, you will see su bject (or camera) motion as if you were exposing at 1/1000. What you may see du e 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 cam era.

I saw an article in a photo magazine a few years ago. A photographer was shootin g other navy jets from the cockpit of a jet fighter. He used the focal plane sh utter on a Speed.

I've never used the focal plane shutter on my Speed, but I would be really surpr ised 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 sh utter is actually open longer than 1/500 sec. Both for exposure calculation and motion blur effects.

Ron Shaw
13-Aug-1998, 18:38
The focal plane shutter on my SG seems quite slow, compared to 35mm cameras. I w ould probably trust the leaf shutter more. The speed of the plane is relative. I f you are some distance from the ground (subject), then the airplane speed may h ave little effect.

John Lehman
13-Aug-1998, 19:01
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.