The pins were usually on shutters meant to work with solenoid
type flash synchronizers to insure they would stay in place. The
pin is usually removable (and is missing on some shutters).
I have not see a shutter than needed more than a hole cut in
the lens board. Note that some shutters can be mounted with the
mounting ring on the back. Some Kodak and other shutters do not
have screw holes on the ring so must be mounted this way. Some
larger shutters can be mounted either way.
Many lens boards are just flat wood or metal with perhaps a
tapered side. Some, like the board for the Pacemaker series Speed
and Crown graphics are stamped sheet metal with folded sides. I
have not tried to make makeshift boards for these. One must use
an original. Earlier Graphic cameras used wood boards that are
easy to make. Most view cameras use plain flat wood or metal
boards. I have even made temporary boards from corrugated
cardboard. Its been a while since I've seen a Linhoff lens board.
Some lens boards have a tab on them to accept a lock screw. I
think this can be makeshifted but I don't have a camera that
needs one.
As far as old shutters go, most just need cleaning. Use
naphtha or Ronsonol lighter fluid for cleaning. Where oil is
needed a good light synthetic oil, like the Labelle oils sold for
model trains works quite well. Very little is needed, mostly on
bearings and sometimes on the escapement of a slow speed timer.
I have not been into a Copal shutter for a while. Some
shutters, mainly Compur and Kodak, have main springs of the
spiral type like small clock motor springs. If they are weak they
must be replaced. Other springs are either helical and can often
be replaced with springs made of stock spring stock or are hair
springs which can be made of piano wire.
Springs become weak through constant use, not standing under
constant compression or extension. The weakening is due to metal
fatigue which requires motion. While it is common to see a
caution not to keep a camera cocked for long periods of time this
actually will not damage springs and some cameras are designed to
be cocked between exposures and are re-wound when the film is
moved. For instance, the self timer in the Rolleiflex Automatic
is kept wound nearly all the time.
When shutters run slow it is usually due to dirt or gelled
up lubricant. Proper cleaning will fix this. Also note that the
marked speeds on many shutters is the _effective_ speed at
maximum aperture measured at the half transmission point. If you
measure the speed for a small stop, sometimes called the total
open time, it is often much slower, perhaps double the marked
value. This, of course depends on the opening and closing time of
the blades. Since that is fairly constant the difference between
marked and effective speed varies with the speed and stop, the
error being greater at higher speeds and smaller stops.
Focal plane shutters have another set of vices all their own.
The _effective_ speed depends on the distance of the shutter
curtain from the focal plane and the angle of the light beam from
the lens. The difference between marked and actual speed can be
relatively small as in many 35mm cameras or quite large, as much
as 50%, for large shutters like the one in Speed Graphics or
Graflex SLR cameras. Where the lens is interchangeable the error
will vary with the focal length (really the back focus) of the
lens and even distance of the lens from the film plane. At one
time it was common to think that the efficiency of a focal plane
shutter was always high but they are no more efficient than leaf
shutters and no more inherently accurate.
On 4/3/2019 12:05 PM, Jean-David Beyer (Redacted sender
jeandavid8 for DMARC) wrote:
On 4/3/19 1:19 PM, mark@xxxxxxxxxxxxxxxxxx wrote:
What I don't know is about the lens boards, and really haven't found a
picture of one. Some are quite simple, but others can be quite
complex. If its just cutting the right size piece of metal and putting
the right size hole in the center, that I can handle. If there are
threads involved, it has light traps and other things as a part of the
lens board, that could get much tougher. Any help would be appreciated.
If I remember correctly, some shutters need, in addition to the big hole
to let the light get through, also a little one to accept an
anti-rotation pin (I do not know its real name). Now you can remove that
pin (it is actually just a little screw whose head sticks out), but it
is nice to have because if you screw on filters, lens shades, etc, you
may not want the lens moving.
Trouble is, I cannot remember if the Copal #1 is one of these, and I
cannot find my special tool to take the lenses off the lens-boards to
find out.
http://skgrimes.com/products/new-copal-shutters/standardcopals
