[rollei_list] Re: Rollei 35S, SE
----- Original Message ----- From: "Eric Goldstein" <egoldste@xxxxxxxxx> 
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Thursday, September 27, 2007 10:29 AM
Subject: [rollei_list] Re: Rollei 35S, SE



It was indeed. An Altman design according to Kingslake...

Eric Goldstein

--

On 9/27/07, Mike Bischof <nbg90455@xxxxxxxxx> wrote:
Wait a minute -- wasn't the Ektar on the Medalist a 5-element Heliar design (in contrast to the 4-element Ektars that were on the Graphics etc.)? 

Mike
Altman claims in his patent (USP 2,279,384) that the extra element is used to control "rim rays", in other words to make the lens sharper when used at large apertures. Kodak made a series of lenses based on this design including the 50mm and 75mm Enlarging Ektars. The Heliar type does not seem to have been very popular. It was exploited by Voigtlander, who held the original Harting patents and to some extent by others. Probably the most familiar beside the Voigtlander Heliar is the Pentac of Dallmeyer designed by Lionel Booth. Cemented lenses were popular with designers before lens coatings became available because they are a way of reducing flare. Once good coatings were available air spaced designs displaced most of the older cemented lenses. From what is in lens design books the Heliar type has some inherent problems which probably also account for its lack of popularity. The Voigtlander Apo-Lanthar is another Heliar type. 

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