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Ari
7-Dec-2017, 19:36
Hi,
I was lucky enough that a dear friend sold me back my old Computar f9 210mm lens, and I'm happy to have it back.
I gave it a quick cleaning when I got home, and noticed that the rear element had a thin brass spacer or shim installed under the element.
Now I can't remember if both front and back elements used a spacer or if it was just the rear one.
Can anyone confirm?
Thanks in advance.

Leigh
7-Dec-2017, 20:43
Shims are used to accommodate slight differences in dimensions of the lens cells or the shutter.

Those result from manufacturing tolerances. They're different for every lens and every shutter.

- Leigh

Jason Greenberg Motamedi
7-Dec-2017, 22:14
Mine has the shim in the rear...

Ari
8-Dec-2017, 13:17
Thanks, guys.
It's worth a couple of sheets to make sure the lens works properly; I haven't had it for some time.

John Layton
8-Dec-2017, 15:33
I owned this lens years ago...lucky to have purchased this new with instructions - which indicated that the included spacer, more than merely placed to accommodate differences in flange measurements - was actually to be utilized to maximize performance for either close or distant work...but I do not remember which.

One must wonder how many lenses we purchase as "used" are missing shims!

Keith Pitman
8-Dec-2017, 17:28
One must wonder how many lenses we purchase as "used" are missing shims!

Or, they come in the box and you wonder forever which side to install them on.

Pfsor
9-Dec-2017, 07:27
Or, they come in the box and you wonder forever which side to install them on.

It doesn't matter for the overall distance between the lens cells. It only matters for the placement of the shutter in between them which is not as critical.

Tin Can
9-Dec-2017, 08:00
I found a shim on my floor and have no idea what lens it fit...

I will be forever looking for my soft/sharp lens problem and it may have come from a visitor's lens.

Worse yet, my old factory made shims and it even could be from there.

dentkimterry
9-Dec-2017, 08:11
I am looking at a G Claron 355mm f9 that is in an incorrect shutter. The owner had the lens in barrell and bought a new copal shutter for it. I know the F stop scale will have to be fixed. I asked if he knew if it needed any shims when he assembled it. He said that he talked to Schneider about it and their answer was that it wasn't that critical because the lens is a symmetrical design. Does that make sense?
Terry

Luis-F-S
9-Dec-2017, 09:29
I bought my 355 G-C in barrel so I had SKG check the optimization when he made the scales for the Copal 3!

asf
10-Dec-2017, 22:20
Rear 1mm shim only for infinity

Ari
11-Dec-2017, 06:18
Rear 1mm shim only for infinity

Funny, I was told the (lone) rear shim was for close-up work.
You're supposed to remove the shim for infinity.

asf
11-Dec-2017, 06:24
Ok, guess we have a 50/50 chance until one of us runs a test Ö

Everything Iíve read says spacer in for infinity, out for greater coverage (11x14) or close up


Sent from my iPhone using Tapatalk

Ari
11-Dec-2017, 06:38
Who doesn't want greater coverage?
Thanks, Adam; I'll burn a couple of sheets soon, but only on 4x5; I'm in between 8x10 cameras at the moment.

asf
11-Dec-2017, 06:41
http://www.largeformatphotography.info/forum/showthread.php?44314-Mounting-a-210m-f9-Computar-in-a-shutter

Ari
11-Dec-2017, 09:53
Thanks