P3D Flash speed

[John Toeppen <toeppen@xxxxxxxx>]

A mechanical shutter takes 1/25 of a second to open, and this is about
the rise time of a flash bulb to peak brightness.  Automatic sync with a
bulb. 1/25 shutter speed is good but not 1/50.  I still use bulbs.  Or
fast negative film.

A strobe has a 100 microsecond risetime = no time at all for all
practical purposes.  This requires a delay to fire the flash when the
shutter is open.  This syncs the strobe with the opening of the shutter.

The notion of a new Realist is interesting.  Unless you have access to
some unique portal in time you have a camera that is old but relatively
unused.  This condition often results in the polymerization of the oils
and thus gumbo in the works.  All of this causes additional delay in a
max opening time and a further loss of sync.

I have often found that upon ten or twenty cock and fires that the sound
an old shutter will change.  A long unused camera will sometimes stick
with the shutter open if the first speed that you try is 1 second.  Test
a camera at 1/25 and then the slower speeds.  You develop an ear for the
sound of a good or bad shutter. Sometimes the speed picks up with use
and the camera may be used as is. Sometimes people just learn what works
for that camera.

But a 2.8 is a favorite camera of some, and good cleaning might be in
order. Or trade it for two or three nice clean f3.5s  Unless you like
ambient light indoor photography.

I personally rarely want to shoot with anything wider than f5.6. I like
good depth of field and I find that stereo need not rely on focus to
isolate the subject from the background.  A sharp flower two and 1/2
feet away can be in front of a mountain that is also in sharp focus.
Which is the subject -- or is it a place with many subjects?   It is
true that the corners get dark from vinyetting(sp?) at f22 but, when you
scan in and write as JPS you crop to a rectangular format to fit a
monitor.  Shoot to format in your final medium when you can....

John Toeppen
http://members.home.net/toeppen/
Photonics West was the Stereo Technology show of the year and well
attended by many neat people showing there stuff..and even some p3d
members.....


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End of PHOTO-3D Digest 3182
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