[rollei_list] Re: "Kaligar" Telephoto Accessory lens for Rollei Automat

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <rollei_list@xxxxxxxxxxxxx>
  • Date: Sun, 26 Feb 2006 21:14:33 -0800


----- Original Message ----- From: "Jerry Lehrer" <jerryleh@xxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Sunday, February 26, 2006 7:31 PM
Subject: [rollei_list] Re: "Kaligar" Telephoto Accessory lens for Rollei Automat


Richard,

No, the Kaligar Accessory lenses have NEVER improved
the optical properties of any prime lens. They only derogated
it.

Jerry

Richard Knoppow wrote:


An afocal attachment has no effect on the stop scale. The
entrance pupil is magnified (or reduced) in the same ratio
as the focal length, so the ratio of its size to the FL
remains the same.
The entrance pupil is the image of the stop as seen from
the front of the lens. Its size is the _effective_ size of
the stop.
This is true for both afocal attachments and for simple
diopter mensicus lenses. The difference is that the menicus
type has no correction and will introduce aberrations into
the optical system where the afocal attachment is at least
partially corrected so the optical properties of the system
are likely to be better.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx



I see how what I wrote could be misinterpreted. I did not mean that an afocal attachment would _improve_ the lens it was used on, only that it would not degrade it as much as a simple diopter lens.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx


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