Super Symmar XLs and removal from shutter

[Tom Stanworth]

Hi,

Just found this on the Schneider website, suggesting that the lens cannot be removed from the shutter without upsetting fine alignments. Anyone know about this? Presumably this does not stop you removing the rear assembly to remove the locking nut to get the lens on an off a panel!!! I presume this means one should not remove teh front assembly from the shutter?

So that its outstanding image quality achieved is not placed at risk, the photographer
must observe the following rules:
¡. The lens, which at great expense was adjusted at the factory during its installation
in the shutter, should never be unscrewed
and taken apart unnecessarily, in order not to change the very precise distance between the front and rear component
which must be maintained, and in order to prevent its being screwed on crooked if both parts are not put back together properly.
2. If, for some reason, the shutter has to be replaced, this must be done only at the factory, because the tolerances which the shutter has must be replaced by a new precise calibration. For just as a Formula-¡ race car tuned for the highest performance
responds more sensitively to “sand in the gears” than a tractor, so does the Super-Symmar XL Aspheric react more sensitively to deficient adjustment in connection
with installation in the shutter than a more simply constructed lens

 

[PHOTOTONE]

Well, it doesn't say you can't, it just says "should never be unscrewed and taken apart unnecessarily." I would think dust or haze on the inside surface of the lens group would be a necessary reason. Probably they may use thin shims to optimize performance. Don't lose them.

 

[GeorgesGiralt]

Hi !
I own an old Zorki Jupiter-8 lens with a totally scratched front lens.
I use it as a paper weight and as a toy when I'm a bit nervous.
The infinity setting is made with an aluminium ring of precise thickness between the lens barrel and the mount into which the barrel is screwed.
Every time I disassemble the lens, on reassembly, the infinity mark has changed, meaning that the ring has been somewhat compressed.
Imagine that Schneider people put a really fine brass collar to adjust cell spacing. This collar having been precisely calculated and made to have the best of the best of the performance. If you squash it when remounting it, or if you do not screw with the right torque, what would you have ? A top of the line lens ? I don't think so.
I own an Apo-Symmar 120. There is a small ring on the front lens barrel. To test, I removed it and made two picts of a distant tree, one with, the other without. There is a difference. Not huge but it shows. I can't find the negs to show you, but I was able to see it using a 10x magnifier.
So better safe than sorry ......

 

[Tom Stanworth]

Thanks for teh replies. I have notices shims with some lenses too. The point I was getting as is the one has to remove the rear section to be able to mount the lens! Surely this is not a problem and therefore were tehy referring to the front rather than rear assembly??

 

[GeorgesGiralt]

Well IMHO, they refer to both.
I suppose the ask to be careful and not to play with the lens, as I do with my zorki, removing cells at will.
The less you touch it the better....

 

[Roger Hicks]

Hi !
Imagine that Schneider people put a really fine brass collar to adjust cell spacing.QUOTE]
Deae Georges,

Except that it's almost certainly very thin German spring steel which distorts a lot less than thick, soft Soviet light alloy. What they're really warning against, I think, is the merry re-shuttering that so many LF enthusiasts indulge in, including 'borrowing' the shutter for another lens.

But I'll second your suggestion to have it apart as little as necessary, and only for panelling at that.

Cheers,

Roger