Skopar front element

SalveSlog · Oct 22, 2024

The front element of the Skopar 4,5/13,5cm on my Voigtländer Avus has the inside lens surfaces fogged. I thought I would be able to take it apart.. but then I read the manual!

From the "Sundry hints" section:
"On no account must any attempt be made to unscrew the separate parts of the front and rear lens elements for it is beyond the skill of even an experienced amateur to put them together again so perfectly as to restore their original optical quality. Anyone who tries the experiment in disregard of this caution will discover to his chagrin the extreme precision with which the assemblage of a lens of this kind is done."

I'm reasonably deft with my head and fingers. Should I heed this warning or not?

Andreas Thaler · Oct 22, 2024

Such explicit warnings from the manufacturer should be heeded.

Without knowing the lens, I could imagine that the lenses in question are not fixed in the only possible position by screw mounts or supports for the optical elements. Then the optical calculation is no longer correct if you don't have any instructions for adjustment.

A service manual showing the structure of the lens would be helpful.

lobitar · Oct 22, 2024

I don't agree. Go ahead and take it apart if you can. If you cannot do it yourself with reasonable care, then probably nobody can. After all it's not rocket science - but perhaps it was in 1926?

Andreas Thaler · Oct 22, 2024

lobitar said:
I don't agree. Go ahead and take it apart if you can. If you cannot do it yourself with reasonable care, then probably nobody can. After all it's not rocket science - but perhaps it was in 1926?

Anyone who can center lens systems and has the equipment to do it can do it properly.

Everyone else can do it more or less well.

You should always know what you are getting into and what you are capable of.

Don_ih · Oct 22, 2024

SalveSlog said:
The front element of the Skopar 4,5/13,5cm on my Voigtländer Avus has the inside lens surfaces fogged

You probably can't make it much worse than internally fogged.

I think I've taken that exact lens apart before and never noticed anything magical about how it was assembled.

Romanko · Oct 22, 2024

Don_ih said:
You probably can't make it much worse than internally fogged.

It is fairly common and inexpensive lens and camera. Go ahead and fix it. There is nothing to lose here. You can get two Avus cameras for the cost of a CLA. It might not be perfect when you put it back together but so be it.

Donald Qualls · Oct 22, 2024

You're talking about separating the two front elements, removing the rear one from the cell? On the only Skopar I own (1927 Rollfilmkamera 6x9 folder) the second element screws into the front cell from the shutter side, and if there are shims they stay on the second element. If you have one that's front-element focusing, however, it'll be a different setup, with a four-start focusing thread that changes the spacing between first and second element. This was very common with Tessars, but I don't know how often it was done with Skopars.

SalveSlog · Oct 22, 2024

It's a plate camera that focuses by moving the whole lens/standard.

And it seem the rear glass is glued to the cell while the front glass can be taken out by unscrewing the ring with the text on it.

Donald Qualls · Oct 22, 2024

Good! So you can't screw up the second element position unless you remove it from the cell, and as long as you don't lose any shims (they'll be behind the front element) it should be easy to return it to correct position. The only gotcha I see is if the front element has lateral play inside the cell, and it likely doesn't or it would be prone to move over time without being disassembled.

Then, of course, the next trick is to get that name ring out without marring it (or accept drilling a pair of small holes for a spanner's pins; the one on my Rollfilmkamera has those from before I got the camera). I'd start with the usual rubber bung type gripper, and several layers of leather to protect the threads from whatever you use to grip the cell itself.

chuckroast · Oct 22, 2024

SalveSlog said:
The front element of the Skopar 4,5/13,5cm on my Voigtländer Avus has the inside lens surfaces fogged. I thought I would be able to take it apart.. but then I read the manual!

From the "Sundry hints" section:
"On no account must any attempt be made to unscrew the separate parts of the front and rear lens elements for it is beyond the skill of even an experienced amateur to put them together again so perfectly as to restore their original optical quality. Anyone who tries the experiment in disregard of this caution will discover to his chagrin the extreme precision with which the assemblage of a lens of this kind is done."

I'm reasonably deft with my head and fingers. Should I heed this warning or not?

YYE told me he won't even work on the Leica mount Skopars because the glue is so hard to overcome on the lenses.

I just had DAG look at one that had internal haze and he told me it was beyond repair because the outgassing of said glue had made the haze permanent and unremovable. (Fortunately, I was still within the return window for the lens.)

These lenses are great when they're clear, but they do have a reputation for getting internal haze. I'd avoid trying to take it apart unless you don't care whether it ever works again or not.

Don_ih · Oct 22, 2024

chuckroast said:
Leica mount Skopars

The Skopar on the Avus is quite a bit older than the Leica Skopars and is likely quite different, though. The Avus was from around 100 years ago.

Marcelo Paniagua · Oct 22, 2024

Probably it needs a collimator to adjust? not everyone has one of those laying around (then and now), so it explains the warning. Just guessing here.

chuckroast · Oct 22, 2024

Don_ih said:
The Skopar on the Avus is quite a bit older than the Leica Skopars and is likely quite different, though. The Avus was from around 100 years ago.

Gotcha.

RalphLambrecht · Oct 22, 2024

SalveSlog said:
The front element of the Skopar 4,5/13,5cm on my Voigtländer Avus has the inside lens surfaces fogged. I thought I would be able to take it apart.. but then I read the manual!

From the "Sundry hints" section:
"On no account must any attempt be made to unscrew the separate parts of the front and rear lens elements for it is beyond the skill of even an experienced amateur to put them together again so perfectly as to restore their original optical quality. Anyone who tries the experiment in disregard of this caution will discover to his chagrin the extreme precision with which the assemblage of a lens of this kind is done."

I'm reasonably deft with my head and fingers. Should I heed this warning or not?

I would take this warning seriously!

Skopar front element

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