rabruner at rabruner at
Wed Jul 14 22:48:50 CDT 2010

>The bad camera shows just a short gap of light at 1/1000 sec.  As I slow 
the speed the gap gets larger until at 1/60 the light is seen all the 
way across.  I will put this camera aside and use the good one.  One of 
the curtains is hanging slightly and will probably need some lubrication 
to the mechanism.  It has been on the shelf for some years and I suspect 
many other fine SLRs have a similar problem and should be checked.

I think you may be shelving the wrong camera:  1/60 second is the X sync speed on an FT chassis camera. That is the fastest speed at which both curtains are fully open.  If both curtains remain wide open at all shutter speeds, it sounds like the trailing curtain is hanging.  The moving slit phenomenon is well known in FP shutter cameras and is the cause of geometric distortion on fast moving objects photographed with high shutter speeds such as race cars.

Here is a quote from

>>For a fast shutter speed or a very short exposure time such as 1/500 sec or 1/2000 sec, the first curtain will not have traveled very far before the second curtain starts chasing it across the frame. The film frame will be exposed by a narrow traveling slit of light formed by the gap between the two curtains. At no time is the complete film frame exposed all at once to light from the lens. For most picture-taking situations, it doesn't matter that the frame was exposed by a traveling slit of light. >>

Bob Bruner

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