[Leica] Has anyone here fixed their own cleaning marks on a lens?

[freakscene at weirdness.com (Marty Deveney)]

Hi Vick,

>Has anyone here fixed their own cleaning marks on a lens?

Before he retired my father was an optical engineer - he showed me how to 
reprofile a scratched lens, among other things.  I am not an expert.

>Is polishing out the cleaning marks hard?  I wouldn't think so, with the
>proper setup.

It is relatively difficult.  Optical glass is very hard, good coatings even 
more so.  You need low-speed polishing equipment that has extremely high 
precision, the right grinding tools and compounds and a fair bit of 
experience to not end up with something that produces results that the Great 
Wall Plastic Factory (the manufacturer of the Diana) would be proud of.  If 
you change the profile of the surface, you will introduce a lot of 
aberrations into the system.  

>Then, what about putting on an anti-reflective coating?  I can't conceive of
>doing that at home, but, what about a UV-cure spin-coated film?

This win't work.  The coating needs to be 1/4 the thickness of the average 
wavelength of light - any variation from this will diminish the performance. 
 A UV cure film will not be consistent enough in terms of thickness or hard 
enough (Leica's coatings, for instance are not as good as Zeiss T* coatings, 
but they are extremely hard).  Even with a plasma coater designed for 
coating lens elements coating is demanding work.

You're obviously very handy - take the lens apart, package the elements up 
and send it to Arax or send the whole lens to John van Stelten and have it 
reprofiled as best as is possible and re-coated.  If the doublets have 
de-cemented these can be separated, the old glue removed and the elements 
re-cemented.  That will make a greater difference to the performance of the 
lens than removing the scratches.  This will get rid of the cleaning marks 
if not the gouge.

Having said all this, I'd send it back, tell the vendor they're dreaming and 
look for another one.

Marty


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