From: rspeirs@javelin.sim.es.com (Ron Speirs)
Subject: Re: Ricoh KR-10 Super questions
Organization: Evans & Sutherland Computer Corporation
Distribution: usa
Date: Thu, 13 Aug 1992 16:38:36 GMT

In article <77563@ut-emx.uucp> lihan@ccwf.cc.utexas.edu (Bruce G. Bostwick) writes:
>OK, I have one for y'all.  I have a Ricoh KR-10 Super from ages ago --
>well used and quite roughly treated but never broken -- that I need to
>recalibrate some things on.
>
>First of all, my flash sync is about 40-50 ms late, causing the bottom
>1/4 frame or so to be clipped at sync speed which is 1/125. (OK, OK,
>yes, I have a rather fast shutter! ;-)  Does anyone out there happen
>to know how to adjust this sync so I can use sync speed for the flash?
>
I don't think that your flash sync is out of adjustment.  Many cameras have
a maximum shutter speed for flash sync of 1/60.  Shooting flash at faster
speeds will result in part of the frame being unexposed.

Consider how a focal plane shutter works:  When the camera is being cocked,
both curtains travel across the frame opening.  When the shutter is released,
the first curtain opens.  After a time delay (determined by the shutter speed),
the second curtain closes over the opening.  Note that the curtains always
travel across the opening at the same speed.  When shutter speeds are slow,
there is a significant time period when the frame is completely open.  However,
when shutter speeds are increased, it reaches a point where the second curtain
starts to close BEFORE the first curtain has completely opened.  At these
faster speeds, there is NO INSTANT when the frame is completely open, and
no appropriate time when the flash can go off to expose the entire frame.
The amount of the frame clipped (unexposed) will increase with faster shutter
speeds, until at 1/1000 you will only get a narrow slit exposed.

Try this experiment with an empty camera:  Take off the lens, open the back.
With flash mounted, look thru the shutter at a light subject and try the
flash at different shutter speeds.  You will then see at which speed the
shutter "clips" the flash exposure.  With my Minolta X- cameras, 1/60 or
slower is OK, 1/125 or faster clips.

Ron Speirs, Evans & Sutherland Computer Corp., Salt Lake City, Utah



>Second, what is the typical method used for checking shutter
>calibration and how is it adjusted if it's off?
>
>Background:  I am _intimately_ familiar with the internal workings of
>the camera, having had to reconnect various and sundry tiny springs
>after the body was bumped rather hard by accident one day.  The whole
>top of the chassis is covered with an orange flexible-laminated
>printed circuit and there are two TINY pots in the section right over
>the viewfinder prism.  I have no manuals of any kind, so I have no
>idea what these pots do and am a little hesitant to go fooling with
>them until I do know.  (I also need to someday find a supply of the
>microscopic metric screws this thing is put together with!)
>
>If anyone knows, or can find manuals which tell, email me.  If I get
>-- 
><BGB>
>lihan@ccwf.cc.utexas.edu        /     "I can't complain,
>(really Bruce Bostwick)        /   but sometimes I still do"
>from the great state of TEXAS /         --Joe Walsh--