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

[Pere Casals]

Because you suppose the shims are made for a specific shutter? I suppose they are rather made for a nominal shutter and for a specific pair of lens cells - much more economical that measuring each shutter individually. Because we don't live (and produce lenses) in an ideal world but in a world of economic constraints.

Shims are not added because shutter dimensions variability. For each cells pair Inter-cell spacing can be adjusted to get better performance for center or for corner, for distant or near objects, or to get good average in different situations.

Some lens designs are specially suitable to allow a lens being optimized by adjusting inter-cell spacing. For example convertible lenses normally can be less optimized than others, in the convertible case front and rear cells are individually corrected, in other designs the rear cell corrects the aberrations generated by front cell in the counter sense, and by adjusting the inter cell-distance it is also adjusted how big are the front cell generated aberrations, so the total amount can be adjusted to a minimum for a particular job or for good overall performance.

It is common that samples having very good center performance also have poorer than normal corners, sometimes this can be balanced with more or less shims.

I can be wrong, but this is what I was told by an optician.

[Pfsor]

Shims are not added because shutter dimensions variability. For each cells pair Inter-cell spacing can be adjusted to get better performance for center or for corner, for distant or near objects, or to get good average in different situations.
...
I can be wrong, but this is what I was told by an optician.

That's my understanding too. Otherwise new shutters (when they were still made) would be sold with their shims and not lenses with their shims.

[Pere Casals]

That's my understanding too. Otherwise new shutters (when they were still made) would be sold with their shims and not lenses with their shims.

... then, I'd ask, shutters sold alone without the lens, had all the same shims for the same model ?

IMHO a shutter it is easy to be manufactured with tight tolerances regarding inter-cell spacing... do perhaps incorporate shims to allow to decrease the inter-cell spacing from nominal ?

Were there lenses (of different eras, perhaps, or mm vs inches norms) with different nominal spacing ?

...I guess this would also be useful to tune a common pictorial lens for close-ups, by reducing spacing... just asking...

[Bob Salomon]

... then, I'd ask, shutters sold alone without the lens, had all the same shims for the same model ?

IMHO a shutter it is easy to be manufactured with tight tolerances regarding inter-cell spacing... do perhaps incorporate shims to allow to decrease the inter-cell spacing from nominal ?
New shutters do not come with shims. Lenses are supplied with shims.
Were there lenses (of different eras, perhaps, or mm vs inches norms) with different nominal spacing ?

...I guess this would also be useful to tune a common pictorial lens for close-ups, by reducing spacing... just asking...

[Leigh]

Shims are not added because shutter dimensions variability.

So you expect shutters to be manufactured with zero tolerance, yes?

You realize that would increase the price by a factor of 10 to 100.

Your optician is obviously unfamiliar with manufacturing techniques.

- Leigh

[Pere Casals]

So you expect shutters to be manufactured with zero tolerance, yes?

You realize that would increase the price by a factor of 10 to 100.

Your optician is obviously unfamiliar with manufacturing techniques.

- Leigh

Leigh, making optical flanges with perfect dimensions is something very easy to achieve, this has even been true even for cheap mass produced cameras. For the LF shutters case it is even easier, we only need a mechanical element ensuring the shutter thickness precision, this is way easier than later measuring the spacing and and placing a matching shim, beyond cost this looks a botched job.

If all shims in spare shutters are of same thickness then this would be to acomodate lenses with different inter-cell specs or to have room to lower inter-cell spacing. If shims (in new spare shutters) are different, then you are right, they use shims to overcome a weird manufacturing variability.

Note that some Rodenstock lenses (for example) incorporate different thickness shims to adjust for optimal inter-cell spacing for a particular couple of cells, but not to overcome shutter manufacturing variables...

[Leigh]

they use shims to overcome a weird manufacturing variability.

Pere,

It's a pity you don't understand the concept of "tolerance" in a manufacturing environment.

- Leigh

[Pere Casals]

Pere,

It's a pity you don't understand the concept of "tolerance" in a manufacturing environment.

- Leigh

Leight, 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 ...

[Pere Casals]

I'm a Master Tool and Die Maker with several decades of experience.

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?

[BrianShaw]

I really don’t want to join this sh!tstorm but this has fascinated me for years...

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.

If shimming is so standardized I would expect such data to be readily known and available.

My only experience with a shutter/lens shim was in 1 out of 6 Kodak Retina III’s I’ve overhauled.