[LargeFormat] Wolley Ex W 6.25" f12.5 series III 8x10

[Richard Knoppow]

At 01:19 PM 08/14/2002 -0700, you wrote:
>I finally got around to fixing this lens I got in a box lot of other 
>neat stuff.
>
>I've noticed that the iris is limited to f12.5 but the glass is much 
>larger than that.
>
>I was wondering what part of life as I or the lens knows it would come 
>to an end if I removed the stop and allowed the iris to open up to it's 
>full potiential?
>
>While I understand anything less that 12.5 will not give desireable 
>sharpness,
>
>but it might be a whole lot easier to focus........unless there's a 
>focus shift when you stop down on this lens.
>
>Any body have any experience with this one?
>
>
>Les
>
  I am not sure what design this lens is but believe its a Series IV Protar. 
  The oversize elements are to prevent mechanical vignetting. The lens
opens to f/12.5 for focusing and composition. It should be stopped down to
f/36 for use. The maximum coverage is at f/45.
  The Wide Angle Protars are part of the family of lenses designed by Paul
Rudolph, of Zeiss, and considered to be the first anastigmats. They are
four elements in two cemented groups. The front is made of "old" glass, the
rear of "new" or Jena glass. Wollensak may well have modified the design.
  You can tell something about the construction of the lens by shining a
flashlight into it and counting reflections. Glass-air refelctions are
bright, cemented surfaces are very dim. Even in single coated lenses the
coated surfaces will have much brighter reflections than the cemented ones.
I have a couple of multicoated lenses and its still possible to
differentiate the surfaces. If I am right each cell will have two bright
and one dim reflection. 
  I think Wollensak may also have made an f/12.5 version of a lens which is
more commonly f/9.5. Essentially a four element double-gauss type but with
all four elements compounded. The reflections from this type will show four
bright and two dim reflections per cell. 
  The same thing about stop applies to this type, wide open is for
composing, the lens is meant to work at around f/22 - f/36 mimimum.
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com