Changing shutters?

[Ed Bray]

I have a query that I would appreciate the answer to.

If I had a 210mm f5.6 Symmar in a No 1 Compur shutter and later purchased a 210mm f5.6 Apo-Symmar in No 1 Copal shutter would I be able to do a straight swap of the shutters and would everything remain the same (barrel distance, aperture)?

TIA

[IanG]

Straight swap would be fine.

Ian

[Sevo]

A Symmar (convertible) or Symmar-S? The latter is very, very like the Apo-Symmar (cynics say the only difference was the name change). The convertible is older and a more different design - I'd proceed more careful there, even though my shuttered ones seem to have the same aperture scale. In either case, measure the total lens height with a precision caliper before and after - if there is a difference, you may need to rearrange the shims (it is hard or impossible to tell which shim compensated cell and which the shutter tolerances - the latter ought to stay with the shutter, the former ought to be moved).

[Ed Bray]

A Symmar (convertible) or Symmar-S? The latter is very, very like the Apo-Symmar (cynics say the only difference was the name change). The convertible is older and a more different design - I'd proceed more careful there, even though my shuttered ones seem to have the same aperture scale. In either case, measure the total lens height with a precision caliper before and after - if there is a difference, you may need to rearrange the shims (it is hard or impossible to tell which shim compensated cell and which the shutter tolerances - the latter ought to stay with the shutter, the former ought to be moved).

It is a Symmar convertible and an Apo-Symmar (no L).

There is nothing wrong with either shutter, I just prefer the more rounded aperture of the Compur to the pentagon design of the Copal aperture.

[Leigh]

The proper depth of a Copal #1 shutter, measured from the front face to the rearmost surface, is 22mm.

If you move lenses between shutters, the first thing to do is measure that dimension on each of the shutters.
Your measurements should have an accuracy of at least 0,1mm.

If the measurements for the two are the same, then move any shims along with the cells.

If the measurements differ, you have a problem and should not proceed without further guidance.

- Leigh

[Dan Fromm]

The proper depth of a Copal #1 shutter, measured from the front face to the rearmost surface, is 22mm.

- Leigh

20.00 mm. See http://www.skgrimes.com/products/new...standardcopals And although everyone says thickness, the distance is measured from the front of the front tube (front cell screws into it) to the rear of the rear tube (rear cell screws into it)

[Leigh]

20.00 mm. See http://www.skgrimes.com/products/new...standardcopals And although everyone says thickness, the distance is measured from the front of the front tube (front cell screws into it) to the rear of the rear tube (rear cell screws into it)

Dan,

I took the 22mm dimension directly from the Copal drawing.

Sorry, but SKG does not make these. Copal does.

- Leigh

[Dan Fromm]

Dan,

I took the 22mm dimension directly from the Copal drawing.

Sorry, but SKG does not make these. Copal does.

- Leigh

Have you measured? I have. Pukka Copal and Compur #1s are 20 mm. The #1 Copals engraved Polaroid Copal are 22 mm. Which drawings did you consult?

[Leigh]

Have you measured? I have. Pukka Copal and Compur #1s are 20 mm. The #1 Copals engraved Polaroid Copal are 22 mm. Which drawings did you consult?

What's a Pukka? Sounds like something you'd apologize for if you did it in public.

You're talking about the cell spacing, which is 20mm ±0,025mm per the Copal spec.

Different reference surface.

As stated in post #4, the 22mm dimension that I gave is from the front face of the shutter,
not from the cell seating plane, as shown in this drawing (dimension at the very bottom):



- Leigh

[Ed Bray]

Ed... Any chance you can do a comparison of the two lenses regarding *gasp* bokeh? Then swap the cells and duplicate the test? I'd really like to see the difference between the round vs. penta iris shape. Ill bet others are interested too. BTW, I'll be doing similar comparisons one of these days.

Yes, I can do that although I will do it using my 6x9 back.

I am surprised this thread has had the legs it has and I have been very interested in all the replies, many thanks to you all.