PDA

View Full Version : Mounting lenses ... confusion!



Uri A
27-Jul-2011, 04:36
Hi folks,

I've got a couple of modern lenses for 8x10 (Schneider, Rodenstock, etc) in modern Copal #3 shutters and I am mounting onto Sinar boards. All available knowledge says that a #3 shutter requires a 64.something mm hole (there are TINY discrepancies about the EXACT size..), and sure enough my two Sinar boards are drilled to 65mm.

There are 3 elements involved: I've noticed that different folks use different words to describe them. I am not pretending to be Dr. Johnson here, but for the purposes of this discussion, lets call them:

1. The BOARD (self explanatory)
2. The SPACER (the non-threaded ring that fits between the BOARD and the RETAINER
3. The RETAINER: the threaded, flanged ring that you use your lens wrench (or screwdriver) on, to screw the lens to the shutter.

OK, so we're all on the same page. Now, I have three questions:

(a): What is the purpose of the spacer, insofar as the retainer could just as eaisily clamp down on the board? It seems that people argue about tenths of millimeters when it comes to drilling the hole in the board... Is it just to increase the amount of pressure (surface area) that is applied to the board (via the spacer) when the retainer is screwed down? If so, why isn't the retainer just thicker?

(b): If the retainer is responsible for applying pressure to the board, why do I have a spacer that is so narrow that it doesn't even touch the board when the retainer is screwed down (it is obviously for a #3 shutter due to the diameter)?

(c): If the spacer is indeed designed to provide mounting pressure, why are we so pedantic about the exact hole bore being 64.whatever 1/10 mm, insofar as the outside diameter of both my spacers is 70mm and the outside diameter of the threaded lens barrel is somewhere around 62-63mm?!

Thanks for your time!

Arne Croell
27-Jul-2011, 08:43
Hi folks,

I've got a couple of modern lenses for 8x10 (Schneider, Rodenstock, etc) in modern Copal #3 shutters and I am mounting onto Sinar boards. All available knowledge says that a #3 shutter requires a 64.something mm hole (there are TINY discrepancies about the EXACT size..), and sure enough my two Sinar boards are drilled to 65mm.

There are 3 elements involved: I've noticed that different folks use different words to describe them. I am not pretending to be Dr. Johnson here, but for the purposes of this discussion, lets call them:

1. The BOARD (self explanatory)
2. The SPACER (the non-threaded ring that fits between the BOARD and the RETAINER
3. The RETAINER: the threaded, flanged ring that you use your lens wrench (or screwdriver) on, to screw the lens to the shutter.

OK, so we're all on the same page. Now, I have three questions:

(a): What is the purpose of the spacer, insofar as the retainer could just as eaisily clamp down on the board? It seems that people argue about tenths of millimeters when it comes to drilling the hole in the board... Is it just to increase the amount of pressure (surface area) that is applied to the board (via the spacer) when the retainer is screwed down? If so, why isn't the retainer just thicker?

(b): If the retainer is responsible for applying pressure to the board, why do I have a spacer that is so narrow that it doesn't even touch the board when the retainer is screwed down (it is obviously for a #3 shutter due to the diameter)?

(c): If the spacer is indeed designed to provide mounting pressure, why are we so pedantic about the exact hole bore being 64.whatever 1/10 mm, insofar as the outside diameter of both my spacers is 70mm and the outside diameter of the threaded lens barrel is somewhere around 62-63mm?!

Thanks for your time!
The "spacer" does not go on the back of the board, it is there to be mounted between the shutter and the front of the board, so that the shutter is set a bit off of the board. This order is not so important for your Sinar boards, but is needed for the much smaller Linhof boards (or similar sizes) where the board locking tab would otherwise interfere with the shutter itself. Mounting the retaining ring from the back through the spacer with the board in place is a bit fiddly, but there is no other way to do it.

Tracy Storer
27-Jul-2011, 09:00
Do not forget, some people use wooden cameras with thicker lensboards. In their case the spacer is omitted from the assembly.

rdenney
27-Jul-2011, 09:12
The retaining ring has a shoulder that extends into the hole on the board. Different retaining rings have different shoulder dimensions, and some rings are flat with no shoulder. This is why the holes in used boards differ slightly in size (and also why the recommended hole size differs slightly).

In my opinion, you do not need the spacer, nor do you need to worry about tenths of a millimeter, for mounting your lens to a Sinar board. You only need the spacer if the retaining ring doesn't get sufficiently tight onto the board because it bottoms out on the threads.

If the retainer is a bit loose in the hole, it's no problem. Center it as best you can, tighten it down, and then don't worry about it. Being parallel is important. Being perfectly centered is not--often you'll be applying rise, fall, and shift in far greater amounts anyway. Within a millimeter is plenty close enough.

Rick "who has drilled holes with a hole saw and then enlarged them with a drum sander, for smaller formats than 8x10" Denney

Mark Stahlke
27-Jul-2011, 09:19
The spacer goes between the shutter and the board. Without a spacer the aperture ring will bind against the board. Some Copal 3 shutters also have a pin on the back that will prevent the shutter seating against the board without a spacer.

Spacers come in two different thicknesses. The thick spacers are used with thin metal boards. The thin spacers are used with thick wooden boards.

BrianShaw
27-Jul-2011, 09:24
In my opinion, you do not need the spacer, nor do you need to worry about tenths of a millimeter, for mounting your lens to a Sinar board. You only need the spacer if the retaining ring doesn't get sufficiently tight onto the board because it bottoms out on the threads.

Thanks for answering the ignorant question I didn't have a chance yet to ask: what's a spacer? None of my lenses have an unthreaded spacer nor do they seem to need one nor do any of my aperture rings bind. I can imagine a situation where a space could be needed but have not yet (about 30 years of LF experience) experienced the need personally. Maybe I don't have enough lenses or cameras!

Mark Stahlke
27-Jul-2011, 09:54
A picture is worth a thousand words. Here is my Nikkor M 450mm in a modern Copal 3 shutter mounted on a thin metal board with a thick spacer between the shutter and the board. You can see the pin and the silver aperture ring on the back of the shutter. Without the spacer the shutter will not sit flat against the board due to the pin. If I removed the pin the silver aperture ring would bind against the board.

BrianShaw
27-Jul-2011, 09:58
Yup, that's worth a 1000 words. I've never seen such a thing. Thanks. How very useful. WOW, where do they come from?

BradS
27-Jul-2011, 10:14
The Copal #3 shutter mounting is different from that of Copal #0 and #1 because the #3 is so big. The spacer allows the #3 to be mounted (as shown in the photos above) on a Linhof Technika style board in a manner such that the shutter controls do not interfere, or, are not impeded by the camera itself. The "spacer" allows the massive copal #3 shutter to stand off from the board thus allowing the shutter controls to move freely - without interference from the lens board sliding locks for example.

The sinar boards, are much larger than technika style boards. There is plenty of room on the Sinar board for a Copal #3 shutter. The copal #3 can be mounted flat on the Sinar board. To do this, the hole in the sinar board is usually a little bigger - closer to 65mm. In this case...

1) remove the rear lens group
2) remove the retaining nut and the spacer.
3) insert copal #3 shutter into the hole.
4) put spcer on from the BACK of the board. It should fit through the hole.
5) screw the retaining ring - it fits inside the spacer and screw down
6) insert the rear group

Notice that if the hole is not big enough for the spacer to fit through - you cannot do it this way. However, every Sinar board that I have ever seen that was factory drilled for a copal #3 works this way. Virtually every technika board with a copal #3 hole works the other way...

make sense?

BradS
27-Jul-2011, 15:32
4) put spacer on from the BACK of the board. It should fit through the hole.


This is incorrect. The spacer should NOT fit through the hole. Sorry for the confusion. I was working form memory and low on coffee.

so, the corrected step is:
4) put spacer on from the BACK of the board. It should not fit through the hole.

Leigh
27-Jul-2011, 22:12
4) put spcer on from the BACK of the board. It should fit through the hole.
Huh?

The spacer OD is larger than the retaining ring OD. If the spacer goes through the hole, there's nothing to press against the back of the board to hold the shutter in place. It will just fall out through the front.

FWIW, the spacer OD is 70mm, while the retaining ring flange OD is 68mm.

The proper mounting hole for a Copal #3 is 64.8mm, which is large enough to clear the barrel of the retaining ring (OD 64.6mm).

- Leigh

BradS
28-Jul-2011, 11:23
Huh?

The spacer OD is larger than the retaining ring OD. If the spacer goes through the hole, there's nothing to press against the back of the board to hold the shutter in place. It will just fall out through the front.

FWIW, the spacer OD is 70mm, while the retaining ring flange OD is 68mm.

The proper mounting hole for a Copal #3 is 64.8mm, which is large enough to clear the barrel of the retaining ring (OD 64.6mm).

- Leigh

Yes. I already corrected my error (see post #10 above).

Leigh
28-Jul-2011, 13:45
Yes. I already corrected my error (see post #10 above).
Yep. My error. I didn't read beyond the post that I quoted.

Sorry.

- Leigh

Uri A
1-Aug-2011, 05:06
thanks everybody for your advice. naturally i am more confused than ever :)

half the people say the spacer goes in front of the board and the other half say behind ........ (the aperture lever functions fine either way BTW)

anyone want to stake their reputation either way? :D

Gem Singer
1-Aug-2011, 05:34
I don't understand why you are confused.

When mounting a Copal 3 shutter on a Sinar metal lens board, the spacer goes in front, between the shutter and the lens board.

I'll stake my reputation on that.

BradS
1-Aug-2011, 07:05
I don't understand why you are confused.

When mounting a Copal 3 shutter on a Sinar metal lens board, the spacer goes in front, between the shutter and the lens board.

I'll stake my reputation on that.

Gene,

There is no need to put the pacer in front with the Sinar boards. The Sinar boards are large enough that there is plenty of room for the controls to move through the full range of motion without interference with the camera. This is obviously not the case when a copal #3 is mounted on a Linhof Tech style board. Thus, it is necessary to mount the spacer up front with technika stye boards but it isn't really necessary on Sinar....with Sinar boards, it doesn't really matter but, as a matter of taste, I prefer to put the spacer behind the Sinar boards.

Can you explain why you state that it is necessary to mount the spacer in front of the sinar boards?

All of my lenses in Copal #3 are mounted on Sinar boards with the spacer behind the board...have been for years and they all look and work fine that way.

Leigh
1-Aug-2011, 07:49
There's no reason to use the spacer in front on the Linhof Technika boards either.

Considering how heavy some of the Copal 3 lenses are I prefer to not move the center of gravity any farther forward than absolutely necessary.

Just mount the shutter with the controls at the side rather than on top, which is how I mount all of my shutters anyway regardless of size. My lenses are usually at eye level when I'm shooting, and it's easier to see the controls when they're on the side. (Note that Copal shutters have scales on both sides, to facilitate use in this orientation.)

The controls all operate normally with no interference or binding at any point.

As to the long screw protruding out the back of the shutter... just remove it. It serves no purpose other than possibly being used as an anti-rotation screw.

http://www.mayadate.org/pix/Copal3Tech96.jpg

- Leigh

Gem Singer
1-Aug-2011, 08:11
Brad,

I'm holding a lens mounted in a Copal 3 shutter in my hand as I answer your question.

It is mounted on a Canham lens board, which is smaller than a Sinar board, but is approx. the same thickness. The size of the lens board is not the issue here.

The spacer ring is located between the back of the shutter and the lens board.

There is a brass pin protruding down from the back of the shutter that rides in a metal slot in the aperture ring and serves to limit the travel of the aperture ring.

Without the spacer ring, the pin would contact the lens board and prevent the shutter from being mounted properly.

I am assuming that the brass pin has been removed from your shutter, which is now mounted directly against the front surface of the lens board.

However, I don't recommend removing the brass pin. When doing so, there is nothing to stop the aperture ring from moving past it's range.

It is not the same as the small index pin on Copal 0 and Copal 1 shutters that can be removed without effecting the shutter controls.

Leigh
1-Aug-2011, 08:15
There is a brass pin protruding down from the back of the shutter that rides in a metal slot in the aperture ring and serves to limit the travel of the aperture ring.
...
However, I don't recommend removing the brass pin. When doing so, there is nothing to stop the aperture ring from moving past it's range.
Sorry, Gene...

Not true.

The screw on the back of the Copal 3 has nothing to do with the operation of the aperture control ring, and does not limit its movement in any way.

- Leigh

Gem Singer
1-Aug-2011, 09:07
Leigh,

I learn something new about photography every day. For all these years, I've been following the instructions for mounting Copal 3 shutters as shown in the pamphlet that comes with Nikon/Nikkor lenses.

I removed the Copal 3 shutter from the Canham lens board, removed the brass pin, and re-mounted the shutter with the spacer ring on the back of the lens board.

The only effect I can notice is that the aperture ring is now able to travel a bit farther than it did with the pin in place. The maximum aperture is slightly larger than f5.6 and the minimum aperture is slightly smaller than f64. I can live with that.

The total effect is nicer with the shutter mounted flat against the lens board, without the spacer ring adding extra extension.

BradS
1-Aug-2011, 09:28
There's no reason to use the spacer in front on the Linhof Technika boards either.

Considering how heavy some of the Copal 3 lenses are I prefer to not move the center of gravity any farther forward than absolutely necessary.

Just mount the shutter with the controls at the side rather than on top, which is how I mount all of my shutters anyway regardless of size. My lenses are usually at eye level when I'm shooting, and it's easier to see the controls when they're on the side. (Note that Copal shutters have scales on both sides, to facilitate use in this orientation.)

The controls all operate normally with no interference or binding at any point.

As to the long screw protruding out the back of the shutter... just remove it. It serves no purpose other than possibly being used as an anti-rotation screw.

http://www.mayadate.org/pix/Copal3Tech96.jpg

- Leigh


Hi Leigh,

I completely agree with you on all of the points above. I especially agree with the desire to not move the weight of the (usually massive) lens any further forward than necessary. I've tried to mount my Copal 3 lenses as you've shown. I don't remember why I decided against that configuration. My memory says that the aperture control lever interfered with the front standard of my camera (Ebony RW45) but I may have to go back and try it (again). I ended up mounting all the Copal #3 stuff in Sinar boards and avoiding the issue. This, of course, necessitates use of the bigger camera with the bigger lenses....but, it's not really that big a deal...

thanks for making the effort to post a photo.

Mark Stahlke
1-Aug-2011, 09:44
This has turned into an interesting and informative discussion.

I disassembled my APO Symmar 240/5.6 in a modern Copal 3 shutter. From the photo below you can see that the only purpose of the brass pin is to limit the range of motion of the aperture ring. When I removed the pin the aperture ring did not move beyond its normal range as constrained by the pin. Obviously there is something internal to the shutter that also limits the range of motion of the aperture ring. I have no idea what it is or how strong it is or what might happen if the aperture ring is forced beyond its normal range. I wonder why the shutter manufacturer saw fit to include the aperture ring stop pin unless its function is to prevent damage to the shutter.

[Edit] Maybe the brass pin is just an anti-rotation device like the set screws in smaller shutters.

Next, I note that this shutter has enough of a shoulder that it can be mounted (sans pin) with the spacer on the rear of the lens board without binding the aperture ring. But, depending on the orientation of the shutter on the board, the lens board mounting mechanism may interfere with the aperture control lever.

I'll keep the pins in my Copal 3 shutters and mount them with the spacer between the shutter and board. Everyone else is free to mount their lenses as they choose.

rdenney
1-Aug-2011, 11:39
[Edit] Maybe the brass pin is just an anti-rotation device like the set screws in smaller shutters.

I don't own a Copal 3--all my big lenses are in Ilex shutters and my 240 is slow enough to fit in a No. 1. But shutters have frequently been equipped with an anti-rotation pin. If the whole backside of the shutter is part of the rotating aperture ring, then an anti-rotation pin would have to project through it somehow. And that would necessitate a slot. So, is the slot there to provide limits for the aperture ring, or just to get the aperture ring out of the way of an anti-rotation pin?

Of course, one could always drill a small hole in the board for the screw to project into, and then they would not have to remove that screw at all.

Rick "extrapolating from the picture" Denney

Leigh
1-Aug-2011, 11:45
Hi Rick,

It appears to be just an anti-rotation pin.

The aperture control ring doesn't actually touch the pin at either end of its travel on any of the four Copal 3 shutters I have.

In all cases the aperture control works exactly the same whether the pin is installed or not.

- Leigh

Gem Singer
1-Aug-2011, 12:20
Rick,

After reading Mark's reason for not removing the brass pin, I re-installed the pin that I had removed from my Copal 3 shutter and re-mounted the shutter on the Canham lens board with the spacer ring placed between the shutter and the lens board.

The brass pin does not appear to be an indexing pin like the small steel pins that are supplied with Copal 0 and Copal 1 shutters.

The larger brass pin on a Copal 3 shutter rides in a carefully contrived slot in the aperture ring that limits its movement to a specific range. However, when removed, it appeared to only have a slight affect on the movement range.

About six or seven years ago I had a Fujinon lens that was mounted in a Copal 3 shutter. The aperture ring on that shutter was a different design than the aperture ring on the shutter of my newer Nikon lens.

Believing that it was merely an indexing pin, I removed the brass pin and lost it. The aperture ring was free to turn way past the numbers on the scale. I needed to have the shutter professionally serviced, and after that it never operated the same as it did when new.

That problem seems to have been solved on the newer Copal 3 shutters, but the memory of that negative experience, when removing the brass pin on the older Copal 3 shutter, lingers on.

rdenney
1-Aug-2011, 12:59
It would appear to me that as the generations of Copal shutters have come and gone, there have been revisions in the way they work. Or, perhaps they work differently with different implementations by lens manufacturers. In any case, the best advice is probably to put the spacer between the shutter and the lens board if the brass pin is in the way. That way, it's not an issue, no matter what the particulars of a given shutter might be.

Rick "inclined to agree that a mere anti-rotation pin would be a stock steel item, not a machined brass part" Denney

Leigh
1-Aug-2011, 15:52
The larger brass pin on a Copal 3 shutter rides in a carefully contrived slot in the aperture ring that limits its movement to a specific range. However, when removed, it appeared to only have a slight affect on the movement range.
It's a clearance slot. The ring does not contact the pin at either end of its rotation.

If it were designed as a stop for the ring, why is it so long?

Size is money in the manufacturing world. No manufacturing engineer would install a part of that size for use as a stop for a thin ring.

- Leigh

Gem Singer
1-Aug-2011, 16:28
Why does the brass pin ride in a slot in the aperture ring? What is the function of the brass pin? I am unable to answer those questions, Leigh.

It sure would be helpful if a person who makes his/her living at designing/repairing Copal shutters would chime in here.

I just feel more comfortable leaving the pin in place and mounting the Copal 3 shutter with the spacer ring placed between the shutter and the lens board.

The front standard of my Canham MQC57 is strong enough to support the weight, and a few more millimeters of extension from the spacer ring doesn't seem to make a difference.

Leigh
1-Aug-2011, 16:31
It sure would be helpful if a person who makes his/her living at designing/repairing Copal shutters would chime in here.
I used to repair LF shutters, both Copal and Compur, along with Nikon and Hasselblad cameras. I'm retired now.

- Leigh

Gem Singer
1-Aug-2011, 17:09
Leigh,

It appears that you are determined to prove that you are right and I am wrong.

Why don't we agree to disagree, and leave it at that?

Leigh
1-Aug-2011, 17:23
Hi Gene,

It's not a personality thing. My comments aren't meant to single you out, nor anyone else.

My only concern is with the accuracy of the archives, on this or any other forum.

The common admonition to newbies is "search the archives".

When they do so, I would hope that the information they find is correct, to the extent that's possible.

I'm sure everyone would agree that the mounting arrangement for the Copal 3 shutter is quite odd. I certainly can't explain it, other than to postulate that it's meant to accommodate a wide range of lensboard thicknesses. I know the spacers are available in at least two different thicknesses.

Thanks.

- Leigh

rdenney
1-Aug-2011, 17:32
My only concern is with the accuracy of the archives, on this or any other forum.

CHIIIRRRRPPP! I'm throwing the BS flag on that one.

I already provided a way for people reading the archives to tread carefully and consider what they see on whatever shutter they have in hand, on the basis of conflicting reports from two people who know what they are looking at. The archives don't need anything beyond that--the people reading them are not children.

Rick "Ten yards for illegal procedure" Denney

Mark Stahlke
1-Aug-2011, 18:00
I dug out the paperwork that came with my Nikkor-M 450mm in a Copal 3 shutter. Here is a quick snapshot that clearly shows the spacer between the shutter and lens board. I don't think Nikon got it wrong.

Leigh
1-Aug-2011, 19:10
Here is a quick snapshot that clearly shows the spacer between the shutter and lens board.
Yes it does.

- Leigh