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I bought an old brass lens and I think the glass needs some good cleaning as there is some dust inside the lens. I do not want to disassemble the lens myself as it has a rack and pignon mechanism and looks pretty complicated. I would like to have a specialist to clean this lens for me. Any suggestions where to send it?
thank you in advance,
Jan
Jan, if it has a rack and pinion mechanism chances are that the lens itself is fairly simple!
Front cell usually unscrews quite easily, and consists of two elements cemented together. Clean the outside. If the cement is going bad, it would have to be recemented which is not quite a DIY-job.
The rear is usually two single elements separated by a spacer washer. Unscrew the "keeper ring", take out the first element. Make a note of which way it's supposed to go. Set it aside. Then remove the spacer ring, and the inner element. Clean this, then put that and the spacer ring back in place. Make sure evrything goes back the same way. Then clean the outer element and remount that. In the end screw in the outer ring, and everything should be the way it was except cleaner!
I've assumed the lens is a Petzval type or similar, which these lenses quite often are. There are some Rapid Rectilinears / Aplanats with rack&pinion too, but they are even simpler to clean: One cemented group each end. The third possibility is a Triplet, which is more sensitive to correct mounting. The outer elements can be dismounted for cleaning, but the central negative element should be left in place. Yet another version is the "Hemi-Anastigmat" and similar, with a cemented pair in one end and a simple meniscus in the other. Again, simple to clean.
So the only lenses to be very careful with are the triplets, which have one negative element quite alone deep inside the barrel.
Ole, thank you very much for instructions but it appears that the cells are not easily removable. I did disasselmble/clean few of my old lenses: RR, both Heliars etc. but this guy seems much more complicated. I can not figure how to unscrew the cells. To me it looks like you have to disassemble rack&pinion mechanism to get access to the inner surface of the cells so this is why I am thinking of sending the lens to the specialist.
regards,
Jan
Jan,
That does make a difference. And in this case I can give no useful advice without having seen the lens, and probably not then either! :)
Ole,
thank you anyway, my guess was that if there small companies offering old lens re-mounting there should be some offering lens cleaning. And I guessed someone might know about that...
regards,
Jan
Jan, you might contact Tim at http://lensn2shutter.com/fungus.html
Although I have not had him clean any of my lens, I have used him to install my 45cm RD artar into a shutter. He is very knowledgeable and has reasonable charges. Good luck. Jon
Thank you Jon, sounds like a good idea - I will e-mail him.
regards,
Jan
John van Stelton of http://focalpointlens.com/ does this sort of work expertly, however I will warn you that his expertise comes at a high cost. If you believe the lens worth a significant investment, then I do recommend sending them to John.
If not, I have always had good luck with a small bit of penetrating oil and a pair of strap-wrenchs...
I'd second your recommendation... he mounted my 19" RDA into a Copal 3 and did a bang up job!Quote:
Originally Posted by Jon Wilson
Next up is a 210 WA Raptar that's going into a Copal 1 shutter.
He's a very busy fellow though! So, be prepared for atleast a month of waiting time.
But, he's well worth it. :)
Cheers