On Nov 7, 2006, at 5:21 AM, mike wilson wrote:
> ... What brought this on?
I've heard this question before in other venues. What is usually
driving it is a desire for electronic flash ("X") synchronization at
all exposure time settings, the way leaf-shutters provide it. The key
requirement of X sync is that the shutter be completely open for a
brief time, and this only happens in a two-curtain focal plane
shutter for some subset of the available exposure time settings.
The only exception for a focal plane shutter I know of that provided
X sync at all settings was the Olympus Pen F series of SLR cameras.
Its shutter was a rotating disk with a wedge cut out of it that
supported timings up to 1/500 second. To achieve shorter exposure
times it had to spin faster, mechanical stresses and ultimate
rotational speed is what limited its shorted timed exposure to 1/500
second. Since the Pen F was a half frame camera, they could use a
similar arrangement today on DSLRs, I imagine, but most people today
have gotten used to 1/4000 and 1/8000 second shutter setting options,
which are likely not achievable with this design while retaining
durability.
Godfrey
--
PDML Pentax-Discuss Mail List
[email protected]
http://pdml.net/mailman/listinfo/pdml_pdml.net
