[LargeFormat] lightweight 300mm enlarging/copy/repro lens?

[Richard Knoppow]

----- Original Message ----- 
From: "Michael Sullivan" <michael@haywood-sullivan.com>
To: <largeformat@f32.net>
Sent: Friday, March 19, 2004 10:42 AM
Subject: [LargeFormat] lightweight 300mm
enlarging/copy/repro lens?


> Dear List,
>
> I'm in need of a lightweight enlarging/copy/repro lens in
the 300m
> length.
> I currently own a Rodenstock Rodagon 300mm, but it is one
heavy beast!!
> In comparison,  my Apo-Nikkor 360mm weighs but a fraction.
> The ideal lens would be optimally used at 3:1 copying
artwork.
>
> Any recommendations?
>
> Michael Sullivan
> THE PRINTWRIGHT STUDIO
> P.O. Box 552
> Marshfield Hills MA 02051
> 617.529.0603 cell
> http://www.haywood-sullivan.com/printwright
>
>
  A process lens like the Apo Artar or Apo Ronar should work
fine. Actually your Apo Nikor should be good although a bit
longer than you want. Most process lenses are optimized for
1:1 but are actually good over a range of about 5:1 to 1:5
(Goerz specs.). Actually, the corrections vary little with
distance out to infinity for the four element "dialyte" type
lens. The main aberration which appears is coma which is
eliminated by stopping down. This should not be a problem at
1:3 even wide open. Some later Goerz Artars, The Red-Dot
series, were optimized for ratios other than 1:1 for some
focal lengths, typically for around 1:3 for barrel mounted
lenses. Shutter mounted late Artars could be ordered
optimized out to about 1:10 for some focal lengths.
  The main advantage of the Rodagon is that it has larger
coverage. It is a Plasmat type. At infinity focus a Plasmat
typically has about 75 degrees coverage where a Dialyte is
limited to about 45 degrees. Of course, at 1:1 the image
circle is double that at infinity focus.
  The longer focal length lens will have a slight advantage
in having somewhat less light fall off at the margins of the
image than the "normal" FL lens. Of course, the paper to
lens distance is greater.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com