[LargeFormat] Dagor77 (Was cult lenses)

[Richard Knoppow]

----- Original Message ----- 
From: "Tim Atherton" <tim@KairosPhoto.com>
To: <largeformat@f32.net>
Sent: Wednesday, June 04, 2003 6:50 AM
Subject: RE: [LargeFormat] Dagor77 (Was cult lenses)


> >   f/8 Dagors were not prototypes. I don't think any
standard
> > Dagors were made in this speed. However, one version of
the
> > wide angle Dagor is f/8 (the Zeiss version is f/9) and
> > Dagors longer than 12" are f/7.7.
>
>
> Weren't all the Wide Angle "Golden" Dagors f8? 3 3/8", 4
3/8" and 6 1/2"
>
> (And if anyone knows the whereabouts of a goerz dagor carl
zeiss jena 180mm
> f9, let me know...)
>
>
> tim
>
  The Wide Angle Dagors made by Goerz American were f/8. I
think some early ones may have been f/9. Those made by Zeiss
were f/9. These have larger coverage than the standard
Dagor, but not by a lot. Goerz claims the Dagor has 87
degrees coverage at f/45. I think the claim for the WA Dagor
is about 100 degrees.
  The Schneider Angulon (not Super Angulon) is a variation
of the Dagor. The orders of power in the cemented components
are reversed. This results in a somewhat thicker lens for
similar glass types. Tronnier resorted to enlarging the end
elements to avoid vignetting. There is also some power
shifted to the rear component to obtain better performance
for distant objects. While the Angulon is an f/6.8 lens it,
like both Dagors, has its maximum coverage at f/45, wide
open its useful for composing but has the same problem with
zonal spherical aberration the Dagor, and indeed, all double
meniscus lenses, does.
  When first announced (1930) Schneider claimed 102degree
coverage for the Angulon. Actually, it does have a circle of
_illumination_ that big, but the image quality is poor
beyond about 90 degrees even at very small stops.
  Modern WA lenses are significantly better than the old
designs but one pays a price in size and weight for that.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com