A Little Help w/ 90mm Angulon 6.8

[uavplane]

I'm rather new to large format photography and I just obtained a 90mm 6.8 Schneider-Kreuznach Angulon for a steal. The shutter and the lens are clean and functional but there is some form of residue buildup on the threads. I would greatly appreciate it if anyone can help me identify the buildup and give some advice on how to clean it. ( I need to move the lens to another lensboard and its stuck.)

http://img594.imageshack.us/img594/461/dscn3614y.jpg



http://img600.imageshack.us/img600/8812/dscn3617.jpg

[IanG]

The Aluminium is corroding badly, once that starts it's extremely difficult to stop and it spreads.

Usually when this occurs the whole of the corrosion has to be removed completely before restoration can take place. You have a serious problem there.

I had to grind away a significant depth when I restored a Speed Graphic (non standard) two or three years ago because when Aluminium corrodes it tracks following the grain structure in all directions.

Not sure what;s the best course of action here it's a specialist job.

Ian

[uavplane]

Ian, thanks for your quick response. So what is the recommended course of action? Should I just try to remove the rear cell?

[IanG]

I wouldn't want to start with that one, to remove the glass from the rear mount would be near impossible.

Probably best to clean carefully with cotton buds gently teasing off the corrosion and see how bad it is before thinking of doing anything else. Most people would then leave it as it is after that as they aren't valuable lenses.

Ian

[BetterSense]

It looks like it's in a speed graphic lens board. These are good lenses for speed graphics, so if it were me I wouldn't even try to get it out of the lens board. If I didn't have a speed graphic I would sell it to someone who does. That corrosions looks mighty bad.

[uavplane]

Thanks guys! I purchased it as a lighter lens to carry in my pack along with my Sinar (didn't plan on using much movements). I guess I'll leave it be for a while.

[IanG]

You need to remove as much of the corrosion as possible because once Aluminium starts to corrode it can spread.

Better a careful clean to try and at lerast stabilise the problem.

Ian

[ic-racer]

I'd use penetrating oil and heat to remove that lens ring

[uavplane]

Thanks all for the advice. I sealed off the rear element and used a bit of penetrating oil and was able to get the lockring off and mounted it onto my Sinar lensboard!