----- Original Message -----
From: "Jerry Lehrer" <jerryleh@xxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, December 28, 2005 1:00 PM
Subject: [rollei_list] Re: Spinning front taking lens and
postings
This is the Goerz Hypergon. I am not sure Zeiss ever built any Hypergons after merging with Goerz. It is not an eleemnt which spins but rather an external light equalizer. The Hypergon covers a very wide angle, something like 120 degrees. It has tremendous light fall off, even more than the rule-of-thumb cos^4 theta rule. In order to partially equalize the fall off the lens came equipped with a sort of obstructive stop in the form of a propeller shaped obstructive stop fitted to the front of the camera. The stop was spun by an air pump. It was supposed to be used for about 85% of the exposure and fall away for the remainder. Because the Hypergon is not corrected for spherical aberration or chromatic aberration it must be used at very small stops, around f/36 to f/45 so the required exposures were long enough to make this set up practical.Ruddy,
You think I am joking about the spinning lens elements?
In fact there was a line of Zeiss(?) lenses that had an
internal component that was deliberately spun by the action
of a pneumatic bulb and rubber air tubing. This was done to
permit uniform exposure an the film. Even Richard can
explain that.
Jerry
--- Richard Knoppow Los Angeles, CA, USA dickburk@xxxxxxxxxxxxx
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