[LargeFormat] multi coating

[Ken Hough]

Multi coating is a VERY simple prospect. Search "vacuum coaters"
"MF2 coating""metalic optical coating"  etc. There are many in the USA that 
will do it.
The problem is the cost. and volume you want to send. I recement lenses as 
a business. I wanted to offer coating better than I could do myself with my 
1947 B+L vacuum coater. I found a company in NJ that was reasonable and 
did Multi coating. He would do just 6 elements as a minimum run. My cost 
was 40.00 total. A good deal considering that the machine costs a couple of 
hundred thousand dollars and takes an hour or so. Then he got greedy.
After 3 years he raised his prices and the minimum number of elements went 
to 50 at a cost of 40.00 each surface. Thats 4000.00 an order. He went out 
of business.
Ken 

From:           	Michael Briggs <MichaelBriggs@Earthlink.net>
To:             	largeformat@f32.net
Subject:        	Re: [LargeFormat] multi coating
Send reply to:  	largeformat@f32.net
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Date sent:      	Sat, 01 Dec 2001 22:33:10 -0600 (CST)

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On 02-Dec-01 Les Newcomer wrote:
> Okay so where does one go to get a lens multi coated?
> 
> les
> Ken Hough wrote:
>> 
>  I disassembled it and had it multi coated.


I am doubtful about the possibility to have any lens multi-coated except as
part of the original manufacturing process, at least at anything other than a
prohibitive cost.  To be effective, multi-coating must be designed for the index
of refraction of the piece of glass being coated.  How would an independent
repair service know this information?  Plus, the labor of applying the multiple
coatings in the correct thickness, different for each glass type, would be
prohibitively expensive (lens manufacturers do many lens elements
simultaneously, using an established procedure on a production line).  I
suppose someone in an optical lab could do it if they felt like it, ignoring
the cost of their own labor.

If you want multi-coating, the cost-effective way to get it is to buy a modern
lens (perhaps used) on which the manufacturer applied multi-coating.

I am aware of only one repair service that offers coating of lenses: Focal
Point, http://www.focalpointlens.com/fp_intro.html.  They don't specifically say
"single" or "multi", but their front page says that they use magnesium
flouride, which is the typical choice for single coating.   Their web pages
imply that their service is offered for repairing single surfaces of a lens and
is too expensive to apply to all air-glass surfaces of a lens.  They also warn
that coatings can't be applied to cemented groups because the cement would be
damaged by the heat of the process.

I have heard that decades ago, when single-coating was newly introduced, it was
fairly common to have existing lenses coated.

--Michael

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        ******Ken Hough Photographic Repair******
         Specializing in Deardorff Refinishing
          Lens Recementing and Shutter repair
          Contribitor to McKeowns Price Guide
                   Deardorff Section
           Custom machined Photographic items
           Text Contents Copyright 1999 KHPR
          http://deardorffcameras.0catch.com/
                   Est. 1980