Re: Enlarger lens options.

"Peter" <w2tga@[EMAIL PROTECTED]
> wrote in message 
news:e9848d99-d0df-41db-a06c-f8d57f9abbca@[EMAIL PROTECTED]
 May 7, 7:32 pm, "otzi" <x...@[EMAIL PROTECTED]
> 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
dickburk@[EMAIL PROTECTED]