How hard/easy to mount lens in a 'new' Copal shutter

[Leigh]

I’ve never seen a table of shutters by lenses that indicates the required shim dimension.
Why not? If I simply never found one online or in manuals, would somebody please point me to one.

That's because tolerance errors are individual, to a specific lens or shutter, not general to a group thereof.

- Leigh

[Leigh]

Do you think making LF shutter flanges with within 0.05mm tolerance is it dificult ?

It's not difficult.

It's expensive.

That's the point you fail to understand.

- Leigh

[BrianShaw]

That's because tolerance errors are individual, to a specific lens or shutter, not general to a group thereof.

- Leigh

Well that's your position, Leigh, which I tend to share. I welcome an answer from those who think otherwise.

EDIT: Interestingly, the one time I saw a shim it was paper and I lost it. The camera performed quite admirably without the shim so when I found it I didn't bother installing.

[Leigh]

Leigh, I understand it perhaps too much, in fact I'm (sadly) all day long programming machine vision cameras for computer vision based metrology in manufacturing lines... quite boring, really ...

That explains much of the misunderstanding.

These shutters were made by people operating machines, not by computers.

Parts produced manually have a much wider range of errors.
Making parts to a tight tolerance manually requires significantly more time ($$$) on the machine.

Now, we have the luxury of measuring individual surfaces while still in the fixture. That was not possible in a manual system. In fact, most parts weren't measured until they got to QC.

- Leigh

[Jim Jones]

Do you think making LF shutter flanges with within 0.05mm tolerance is it dificult ?

Copal made clockworks with dozens of 0.001 precision components, but were they unable to make precision optical flanges ? having to add 0.5mm shims for brand's shame?

A between-the-lens shutter is much more than a simple tube. Between the lens cells are several components that affect their seperation. Any cumulative error in these components could be compensated for with easy-to-lose shims. Better yet, the lens cell mating surface could be machined down after shutter assembly to the desired overall length. The lens elements and their mounts have even more potential for errors. Shims provide the logical say to compensate for this on an individual basis by the lens maker.

[Pere Casals]

It's not difficult.

It's expensive.

That's the point you fail to understand.

- Leigh

In series production making 2 metal flanges of that size matching a distance within 0.05mm is under $0.3.

Of course making a unique custom part has higher costs, because and employee can spend a full morning with it, but with repetitive works an automated lathe makes precision parts at very low cost. If you go to a hardware shop you may find thousands of parts with within 0.05mm precision for lens than 10 cents each.

[Pere Casals]

A between-the-lens shutter is much more than a simple tube. Between the lens cells are several components that affect their seperation. Any cumulative error in these components could be compensated for with easy-to-lose shims. Better yet, the lens cell mating surface could be machined down after shutter assembly to the desired overall length. The lens elements and their mounts have even more potential for errors. Shims provide the logical say to compensate for this on an individual basis by the lens maker.

If the mechanical designer was not absolutely incompetent, it was pretty easy to ensure flange distance, if you disassemble any modern shutter you will always find some simple parts across the shutter body made with precision that are intended to ensure a consistent inter-flange distance.

[Leigh]

but with repetitive works an automated lathe makes precision parts at very low cost.

That's certainly true.

And that's also certainly NOT the point of this discussion.

When these shutters were made, they were done by hand, not on an automated lathe.
In that environment, precision definitely does add to the cost.

- Leigh

[Sal Santamaura]

Very simple, unscrew the front and back cells from the old shutter, be sure to keep any shims.
Screw the cells into the new shutter replacing any shims from the old shutter.
If the aperture scales are different on the shutters unscrew the scale from the old shutter and install it on the new one.

Bob provided a complete answer in his post (#2). Everything after that has served only to confuse the matter.

First, although supplies are dwindling, new Copal shutters are still available. Second, shims are used to fine tune cell spacing so that optical variations can be compensated, not because of shutter manufacturing tolerances. Those optical variations are more than an order of magnitude greater than Copal's thickness tolerance.

Using Rodenstock as an example, shims ranged from 0.5 to 1.5mm. Copal shutters carry a thickness tolerance of ±0.025mm.

[Pere Casals]

That's certainly true.

And that's also certainly NOT the point of this discussion.

When these shutters were made, they were done by hand, not on an automated lathe.
In that environment, precision definitely does add to the cost.

- Leigh

The assembly was made by hand, but the component parts ensuring tolerance were made by automated manufacturing.

Just previous post repeats it: Copal shutters carry a thickness tolerance of ±0.025mm, this ends the debate, IMHO.