The Leica Look/Glow

["Richard W. Hemingway" <n5xrd@telepath.com>]

This subject has been discussed about to death; however, having said that I
should remark that the reason that I have returned twice to Leica (usually
M) is becuase my slides taken with the M and usually the 35/2.0 had a
"look," smoothness, roundness, whatever - that I didn't see in the other
camera slides.  I can't describe it but it was there.
I have seen this described as shadow detail, etc., also.

I am assuming that this effect does exist - and have been wondering what
might contribute to it.  I am sure that the accuracy of manufacture,
centering etc all affect this.  However, one aspect that I have not seen
discussed it the manner of polishing of the lens elements.  

At one time I was a telescope nut and remembered in the book "How to make a
Telescope, 2nd ed" on pages 87 - 91 Jean Texereau talked about the effect of
micro-ripple on optical surfaces.  This is a very small effect caused by
different types of polishing materials. he states:

        "These defects have a width of the order of a millimeter and an
amplitude of only         a thousandth of a wave (several Angstroms), but
there are millions of them on the         optical surface and in serious
cases the corresponding diffracted light         represents a perceptible
level of stray light over the entire field. Micro-ripple         is
something to be particularly mindful of in the difficult case of faint
object         of interest near a brilliant source..."

On page 90 he has Lyotgrpahs of such surfaces.

My question is - does anyone know about Leica's polishing materials and
techniques and whether they differ from the techniques used by high volume
lens manufacturers??? Or whether Leica lens have less micro-ripple than
others???

Or is the effect due only to optical design???  I think that someone has
said as much but I don't remember any discussion of the type of design that
would produce this.

Just a thought on a rainy night with nothing else to do.

Dick Hemingway
Norman, OK