are copal 0 shutters generic?

[sharktooth]

He's taking the scale and lens elements from his original shutter that isn't working, and putting them on a different working shutter. This will tell him if the original lens and scale works properly on the working shutter.

[xkaes]

He's taking the scale and lens elements from his original shutter that isn't working, and putting them on a different working shutter. This will tell him if the original lens and scale works properly on the working shutter.

And he's taking the scale from one lens for use with another lens. Here's an example.

I have Copal #0 shutters on a Fujinon 150mm f5.6 and a 65mm f5.6. They are both f5.6 lenses, but they achieve f5.6 at different points of the aperture depending on the focal length of the lens. On the 150mm when the aperture is fully open, the dial points to f5.6. On the 65mm lens, the dial points to about f3.5 -- or where it would be if the scale had f3.5 on it.

I can take the scale off of the 65mm and place it on the 150mm lens -- it fits -- but when I dial in f5.6 it's really at about f9.5.

On the flip side, I can take the scale off of the 150mm and place it on the 65mm lens -- it fits -- but to get f5.6, I have to set it at about f9.5.

So the f-stop scale becomes useless if used with a focal length lens it was not designed for.

There's no need to run through your test. If the focal length is different, the f-stops will be different.

[norly]

This is getting a bit confusing.

Assuming that all copal 0 shutters are technically the same, and logically they should be. I can not imagine that Copal would produce a unique Shutter for each lens ever made.

So, I will assume that the aperture hole on fully open, and fully closed Copal will always measure the same on all Copal 0 shutters. (when the aperture level is moved to the maximum left or right)

Then logically the only difference between the Copal shutter from a 74mm and a 150 mm is the scale. And if I move the scale from one Copal to the Next that will compensate for any difference based on the lens design and focal length. The different scales also starts on different positions but they all end at the same final aperture opening (not aperture number, the actual mm the lens is open).

For example:

On my 135mm Rodenstock the scale is from 5.6-64
On my 47mm Schneider XL the scale is from 5.6-32
On my 72mm Schneider XL the scale is from 5.6-45

When I move all of these lenses aperture level to the furthest right on the scale, the size of the small hole is identical. That would mean that the 72 mm XL is one step brighter then the the 47 and 2 steps compared to the 135. But the size of the shutter hole is the same, so it is a lens factor, not a shutter design factor.

Same if I move all lenses to 5.6 on the scale. Then the openings are 100% open (if I look thou the glass). The wide lenses can be moved another 1-2 steps after the scale ends, but since the glas/lens is smaller I can not se the last 2 steps, since they are outside the lens visible circle. That mens that on all lenses, if I set 5.6 the lens is 100% open compared to the lens that belong to the scale.

Logically then if I move the scales from one Copal to the next and move the glas elements that fits the scale, It has to be correct apertures.

It makes sense.

[norly]

He's taking the scale and lens elements from his original shutter that isn't working, and putting them on a different working shutter. This will tell him if the original lens and scale works properly on the working shutter.

Yes. This is exactly what I am doing.

I move lens elements, distance rings and scales from a lens with a broken Copal 0 shutter and put them on another random Copal 0 shutter.

And I fail to se why this would not work. The scale can only be mounted in one way (the same fit on all shutters) and it compensates for any differens in light due to lens design by being longer, shorter and so on.

The only way this would become a problem is if the actual design of the shutter mechanics was lens specific on the Copal 0 shutters. And that would be an extremely unpractical way to design something that can be adjusted by a simple scale..

[sharktooth]

Yes, that does work, as long as you're moving both the scale and the lens elements to a different shutter of the same size (Copal 0). It doesn't work if you put on a scale that is for a different focal length lens.

[Bob Salomon]

Yes, that does work, as long as you're moving both the scale and the lens elements to a different shutter of the same size (Copal 0). It doesn't work if you put on a scale that is for a different focal length lens.

Or, if you lose the proper shims for your lens.

[sharktooth]

This is getting a bit confusing.

Assuming that all copal 0 shutters are technically the same, and logically they should be. I can not imagine that Copal would produce a unique Shutter for each lens ever made.

So, I will assume that the aperture hole on fully open, and fully closed Copal will always measure the same on all Copal 0 shutters. (when the aperture level is moved to the maximum left or right)

Then logically the only difference between the Copal shutter from a 74mm and a 150 mm is the scale. And if I move the scale from one Copal to the Next that will compensate for any difference based on the lens design and focal length. The different scales also starts on different positions but they all end at the same final aperture opening (not aperture number, the actual mm the lens is open).

For example:

On my 135mm Rodenstock the scale is from 5.6-64
On my 47mm Schneider XL the scale is from 5.6-32
On my 72mm Schneider XL the scale is from 5.6-45

When I move all of these lenses aperture level to the furthest right on the scale, the size of the small hole is identical. That would mean that the 72 mm XL is one step brighter then the the 47 and 2 steps compared to the 135. But the size of the shutter hole is the same, so it is a lens factor, not a shutter design factor.

Same if I move all lenses to 5.6 on the scale. Then the openings are 100% open (if I look thou the glass). The wide lenses can be moved another 1-2 steps after the scale ends, but since the glas/lens is smaller I can not se the last 2 steps, since they are outside the lens visible circle. That mens that on all lenses, if I set 5.6 the lens is 100% open compared to the lens that belong to the scale.

Logically then if I move the scales from one Copal to the next and move the glas elements that fits the scale, It has to be correct apertures.

It makes sense.

It's hard to tell if you're understanding the relationships correctly, since some of the terminology you're using is open to different interpretations.

Aperture can mean different things. In general English usage it's just a hole size, but in photographic terms we often describe the f number as the aperture. Those are completely different things. The f number is simply the ratio of the focal length to the effective diaphragm opening diameter (for a simple lens). View camera lenses are not "simple" lenses, so there is a bit of additional correction to this ratio based on lens design, but that doesn't really change things too much.

A 150mm focal length lens at f5.6 will have a diaphragm opening diameter of roughly 26.8mm (150/5.6), while a 90mm focal length lens at f5.6 will have a diaphragm opening diameter of roughly 16.1mm (90/5.6). These are two completely different diaphragm opening diameters, even though the lenses are both set to f5.6. The lens maker will make a scale that correlates the actual diaphragm opening diameter to the f number scale that's needed for each particular lens. This is why you need different aperture f stop scales for different focal length lenses.

The shutter has two sets of blades, namely the shutter blades, and the diaphragm blades. The shutter blades open and close completely each time the shutter is fired, but they don't restrict the light coming into the lens except by time (shutter speed). The diaphragm blades can be variably opened or closed down to any diameter you want using the setting lever, and they don't move when the shutter is actuated, so they always restrict the light coming through the lens via opening size.

[sharktooth]

Or, if you lose the proper shims for your lens.

Good point. Something else to watch out for.

[Dan Fromm]

This is getting a bit confusing.

Assuming that all copal 0 shutters are technically the same, and logically they should be. I can not imagine that Copal would produce a unique Shutter for each lens ever made.

So, I will assume that the aperture hole on fully open, and fully closed Copal will always measure the same on all Copal 0 shutters. (when the aperture level is moved to the maximum left or right)

So far, so good. But as usual there are fine details that trip some folks up. I think the shutters you're thinking of are ok, but some Copal shutters used in lenses for the Polaroid MP-4 have diaphragms that are limited and won't open to the usual 25mm.

Then logically the only difference between the Copal shutter from a 74mm and a 150 mm is the scale. And if I move the scale from one Copal to the Next that will compensate for any difference based on the lens design and focal length. The different scales also starts on different positions but they all end at the same final aperture opening (not aperture number, the actual mm the lens is open).

Not so fast. The f/stop is the diameter of the lens' entrance pupil / focal length. The entrance pupil is the diaphragm's diameter as seen from the front of the lens. Different lenses' front cells can have different magnifications.

Tne rest of y'r post is in outer space.

I've moved lens cells from one shutter to another, also from a barrel to a shutter. The shutters usually have aperture scales that aren't appropriate for the lenses. I can use them anyway. The trick is to hold the lens at arm's length, front cell facing me. Then slowly close the diaphragm until the diaphragm blades disappear. Open the diaphragm a bit, stop down a bit, ... until I'm confident that I've nailed the opening at which the blades vanish from/come into view. The scale marking at which this happens corresponds to the lens' maximum aperture. If the magic spot is off the aperture scale's low end, I sent the shutter and lens to a shop such as SKGrimes to have the right scale attached or engraved.

I think I've just told you how to test that an aperture scale is right for a lens. If the magic spot is at the marked aperture that corresponds to the lens' maximum aperture, all's well. If not, not.

Good luck, have fun.

[norly]

Thanks for all the help.

Sorry if my terminology is a bit off and if it gets confusing.

Shall we agree that the following statements are true?

1. The standard Copal 0 are all mechanically/technically the same.
2. The aperture scales on the Copal 0 are lens specific
4. The standard Copal 0 are interchangeable if you move lens elements, shims and scales from the old one to the new one

Of course is you have engraved aperture scales, then it does not work. But all of mine are easily removable.