"Peter" wrote in message
...
On May 7, 7:32 pm, "otzi" wrote:
....

I just wondered if the HM was more for colour work, rather
than B&W.- Hide quoted text -

- Show quoted text -

Sometimes Bob Salomon posts on this board and he would have
more
details at his fingertips.

My opinion is that unless you need the extra coverage the
obvious
choice is whichever is cheaper. It wll be hard to see a
difference in
image quality between the lenses using either B&W or color.
The
Componon-S, the Rodagon, the Nikon and the HM Componon are
excellent
lenses (usually - individual variation or especially damage
in a used
lens is possible).

One problem with "wide angle" enlarging lenses is light
fall off. Fall off is due to geometric properties and
increases with the image angle. It can be reduced to some
degree in some types of wide angle lenses but I don't think
this principal is used for enlarging lenses. As an example I
use a 135mm lens for enlarging 4x5 negatives and must burn
the corners. Standard for this format is 150mm but 180mm
would be better for corner to corner uniformity, however, it
would require a very long throw (tall column). I concur
that unless you need a wide angle lens because of lack of
projection space its better to use a longer focal length.
As far as the MTF charts from the various manufacturers
go they really don't tell you much. Rodenstock's chromatic
correction curve shows that their "apo" lenses are not
apochromatic but acromatic and AFAIK so are Schneider's.
This really makes no practical difference because both lines
are very well corrected.
For the most part the older Schneider Componon-S is
excellent and there is not a lot to be gained by using newer
and much more expensive lenses although their performance is
marginally better.
BTW, one of the reasons for the redesign of both
enlarging and camera lenses in the last couple of decades is
the lack of certain kinds of optical glass due to some
components being considered environmental hazards. For
instance arsenic was a common ingredient in glass to clarify
it and must not be used now. Since some of the glass
constants have changed the designs have had to be changed.
Not a big deal with computer assisted design but it does
require making some changes. The original Tessar could not
be built now because the glass types it calls for are no
longer available.


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Richard Knoppow
Los Angeles, CA, USA