jup12 front lens...

Would a early Jup 12 frontlens be exhangeable with a wartime biogon 35 front lens...? because of course I've a wonderfull biogon 35 T LTM with very nice glass except a scratched front lens... someone did iceskating on this front lens... and I would love to use it, of course.
SO
1/ is it possible ?
2/ does anyone have a wrecked early jup 12 with a clean front lens...

as usually jup 12 are prone to have back lens scratched I may have some chance.

Stephan

Stephan

Stephan,

it is an interesting point if the front lenses are exchangeable. As I know the J-12 is an exact rebuild of the prewar 2,8/35 Biogon.
So maybe it is possible to change the lens. Just try it :-) I don't have a wrecked up one for sell.

Ulrich
PS: If you want to have a post-war 2,8/35 Opton Biogon with a scratch on the front lens let me know ;-)

http://fotos.cconin.de

I have a nice Jup12 53 but it's too nice to cannibalise...
and Opton biogon I got 2 already (And 3 sonnars 1,5) and a rare orthometar and so on...

I'll try ... and I'll tell you about it.

Stephan

This is not a simple task! at least diameters are different.
I Have tried once and refocusing lens become a problem.When done final results became poor.
J12 and Opton Biotar have complete different glasses.
Competent Polishing is the best way to renew te lens.
LP

the swap would be between a prewar formula biogon (but T) and a jup12 .... the post war opton biogon is a different formula indeed...


Stephan

Also there are differences on prewar Sonnars and Jupiter 12s
I dont know between prewar Sonnars and "ZK 35"
LP

I won't cannibalise a BK to save even a true LTM biogon... but an early jup12 may be...

to be clear
Biogon 35/2,8 > BK > jup 12
Sonnar 50/2 > ZK 50/2 > jup 8
Sonnar 50/1,5 > ZK 50/1,5 > jup 3
Sonnar 85/2 > ZK 85/2 > jup 9
Sonnar 135 > jup 11

Stephan

Your table is completely correct.
I took a mistake calling the Biogon as Sonnar and BK as ZK... But mathematically speaking Biogon 35mm have the same basic formula from Sonnars. By that reason All of them are called Jupiter in the next generation. That does not apply to post war Biogon 21mm that were derived from "MR" lenses.
Regards
LP