[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Eclair ACL S-16 Shutter --- one person's opinion
In the end, everyone goes with what works best for them. Some folks take
Pentium 500 computers and overclock them .. 550 ... 600... 650 ...700. Where
is the "grey-line" that you can get away with, versus risking incorrect
output or a crash? For some people it is 500 --- if they need a 550, they'll
buy a Factory 550. For many, or perhaps most, it may be that overclocking to
550 seems well within tolerance. A smaller group of folks like to push the
envelop to see what they can get by with by installing special super-cooling
fans, and they'll see how many days the system can run with
processor-intensive software without making a mistake or crashing, and then
they'll use the computer knowing the maximum period of time that it can go
until it needs to be shut down and cooled. None of them is right or wrong.
Each does what makes sense for them.
The Eclair factory specs in R-16 call for the timing of the shutter and
mirror to be such that when the shutter is open, the mirror is not blocking
any part of the exposed film. Modifying or Replacing the R-16 Shutter with a
S-16 Shutter that has a smaller angle (to give the mirror the extra time to
clear the wider aperture) is a prudent extension of the basic Eclair ACL R-16
specs to the S-16 format.
The number 144 is not etched in stone. At 24fps, it was the next number in
line after 175 that yielded an "industry standard" exposure time (1/60th), so
that's what I went with in designing the HD-144 shutter. It is 1/3rd of a
stop difference. (As fate would have it, there is also an advantage when
shooting an NTSC TV screen, and the timing of the pulldown claw has a
slightly greater tolerance for error, but those are just small fringe
144 degrees is on the conservative side; 175 degrees just barely lets the
mirror clear in Regular-16. So where is the "grey-line"? What is the
equivalent of a "Factory Spec" Shutter Angle for S-16? Here is where
qualified people may have a valid diversity of opinions, and then it is up to
each user to determine his or her needs. My answer was 144.
For a student film or short just struggling to get by financially, specs may
be far less of a concern as long as the film gets made, and that's
understandable. At that level you could also get by with not recentering the
lens flange just by staying on a 25mm lens. Indeed, just taking a file and
opening up the size of the frame in the aperture plate will also work if you
are careful to keep the track support very clean and free of static charge.
And I don't say any of this with sarcasm --- a decade ago I did it that way,
and it cost nothing.
For me personally, not adjusting the shutter angle by a certain amount to
reflect the aperture modification is dropping too far below specs for the ACL
to be considered a viable camera of equal quality to the Arri SR and the
Aaton. I'd really urge anyone with 175 degree shutter in their S-16 ACL to
spend a hundred dollars and ask your Tech to glue in a very thin piece of
metal to close it down enough to let the mirror clear. Keep the S-16 ACL
above the "grey-line."
This email was sent to: email@example.com
EASY UNSUBSCRIBE click here: http://topica.com/u/?a84xYK.a9svPI
Or send an email to: EclairACLfirstname.lastname@example.org
T O P I C A -- Register now to manage your mail!