Re: [Leica] CoF and Macro

["Jacques Bilinski" <jbilin@axionet.com>]

My understanding is that as the APO macro 100mm is focused at close
distances it acts like not like a regular 100mm on the end of a bellows but
rather like a lens of shorter focal length focused at a close distance. I
think this is what Adrian was referring to when he stated that this lens
shares some attributes with a zoom lens.

Since I don't have one of these I can't do any tests. But someone who owns
one could try projecting an image of a distant subject on a groundglass with
the lens (the 100mm APO macro) focused at infinity and also with the lens
set to a close distance. I suspect that the magnification would be higher
with the lens set at infinity. This means that at closer distances this lens
is no longer a real 100mm lens but acts like a shorter focal length lens.
This also implies less light reduction at close distances (a plus), a
shorter distance to the subject (often a minus), and a smaller physical size
of the lens.