Re: [Leica] CoF and Macro

[apbbeijing <apbbeijing@yahoo.com>]

Erwin,

Thanks for the enlightening answer!

I am aware of the general construction pattern of zoom optics but still
reckon that the 100APO uses an Elpro rather than the usual extra extension
in order to maintain a long focal length at high repro ratios and keep a
flat field due to the corrective rear group: I understand that the 100APO
loses more focal length at close focussing settings than say the 100 Macro
Elmar due to the addition of the extra group of stationary optics at the
rear. Is this correct? In any case it is only of idle interest to me since I
am not a big macro user. I find the 60 Macro fits my needs much better
anyway! I would still like to hear from the horse's mouth though so let us
know what you learn from Solms. My methods are not as rigorous as yours nor
my memory so good so I am grateful to be corrected about Herr Kölsch's
involvement. Maybe you could let us know where he came in design wise in the
current line up?

In the Canon line the old 100 EF Macro lost a lot of focal length at 1:1 and
was not much different to the 50/2.5 Macro with it's close up
adapter/extender which is basically a teleconverter producing a 70mm or so
lens at 1:1.

My experience is that the dual element close-up lenses are better at
maintaining a flat field (for the lenses for which they are recommended by
the manufacturer) than extension tubes and far better than single element
close-up lenses. They are not as sharp as real macro lenses though and I do
stop way down.

Whilst I am addressing you about optics: what do you know about the Zeiss
S-Orthoplanar and S-Biogon lenses as enlarging optics? I understand they are
the absolute best lenses for enlargements though they were not intended for
regular photography. Have you ever compared them to the best Apo Componons
and Apo Rodagons, the Leica lenses or the legendary Apo El Nikkor 105mm?
Just wondered at which point the difference might be noticeable...

Bests

Adrian
- -- 
Adrian Bradshaw
Corporate and Editorial Photography
Beijing, China
tel/fax +86 10 6532 5112
mobile +86 139 108 22292
e-mail apbbeijing@yahoo.com
OR adrianpeterbradshaw@compuserve.com

website:   http://www.apbphoto.com
           http://www.liaisonintl.com/bradshaw.htm
           http://www.liaisonintl.com/bradshaw_e.htm



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