Re: [Rollei] Rollei Users list digest V10 #100

[Richard Knoppow <dickburk >]

At 09:24 AM 12/19/2001 -0800, you wrote:
>I have an Ektar I=on my 1000F which believe it our not works great, I would
>be happy to count the elements if someone tells me how to do so Mark
>
>
  If a lens is not too complex its possible to get some idea of its
construction by counting the reflections from a small source, like a pencil
flashlight. Uncoated glass air surfaces have a quite bright reflection.
Cemented surfaces have a very dim, but visible reflection, coated glass-air
surfaces are somewhere in-between, but even multi-coated surfaces are
usually a little brighter than a cemented surface and single coated
surfaces are much brighter.
  If the curvature of a surface, especially a cemented one, is extreme it
may be difficult to see but usually shining the light from both ends will
show up all surfaces. Its helpful if the cells are removable and can be
examined individually. 
  With some practice its possible to tell if the surface is convex or
concave toward you but mostly just the number of elements in each section
and whether they are air spaced or cemented is enough to identify a given
construction. 

- ----
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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