Re: HIE and Leica M

[Larry Bullis <lbullis@xxxxxxxxxxx>]

> > You may notice that there is no infrared mark on your Leica lenses.  
[.....]

> 
> The 'not doing things half-way' theory is correct, but not like you 
> said. It is claimed that Leica found the IR-focus indicator useless, 
> as it applies to infinity focus only....nearby the error is different 
> (I don't know in which direction....anyone?).
> 
Well, it would have to be longer and longer.  It seems that it works by a 
percentage; in other words, the ir focus makes a slightly longer lens of 
it for ir than for visible light.  I don't remember the percentage 
increase in extension Kodak suggests, but if you apply that extension to 
the nearer (extended) focus, it would always be longer.

Thanks for clearing this up.  Very interesting.

Larry Bullis 
Skagit Valley College
(but now in Tacoma, for whatever that's worth!)

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