Re: IR with a 500 mm mirror telelens?

[Steve Hodges <shodges@xxxxxxxxxxxxxx>]

If the lens has no other elements other than mirrors, you need no
correction.  In practical cat lenses there are a number of glass
elements.  

This leads me to suspect that the focus change would be negligible, but
my cat lens has no IR marking and I've not used it for IR.

Eckhard Stephan wrote:
> 
> I think that some focus
> corrections might be necessary, especially with Konica IR (I never used
> any focus corrections for HIE with a #25 so far). Unfortunately, the
> mirror tele hasn't got any IR focusing marks. So I'm not quite sure how
> to focus... Any suggestions will be greatly appreciated.

You correct focus with Konica, but not with HIE?

Steve
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