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Clip-on and D-mount Wollensak 1½ inch f/3.5 cine telephoto
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PostPosted: Fri Aug 11, 2017 12:27 pm    Post subject: Clip-on and D-mount Wollensak 1½ inch f/3.5 cine telephoto Reply with quote

The Wollensak Cine Telephoto lens of 1½ inches focal length for Bell & Howell Filmo 8s, also sold as Bell & Howell Telate, is a triplet. The less satisfying punch-through diaphragm leaves again. Pinching threaded bushes and nothing to secure the lens from being screwed apart, a mess. This one cost me $13 with eBay.

$42 in 1948, $426.89 as of today. When bought from the Bell & Howell Company, the price was $46 in 1940, $804.85 today. Theft.



I shall report about other ciné lenses, better ones, also cheaply available now. Not that it were impossible to shoot with Wollensak lenses, but after all these years we must have a closer look at the mechanics and what future they probably have. One could of course stamp fresh diaphragm leaves from spring steel stock, press in pivots, harden and anneal them, and thus breathe new life into such a lens. I won’t do that, just CLA.


PostPosted: Sat Sep 02, 2017 2:16 am    Post subject: Reply with quote

Good work Like 1


PostPosted: Sun Oct 15, 2017 3:28 am    Post subject: Reply with quote

Hello,

Can you tell me how many glass elements are in front. I'd like to clean mine but I'd prefer now more about its architecture before.

Thanks !


PostPosted: Fri Oct 20, 2017 9:03 am    Post subject: Reply with quote

Negens, you don’t read too carefully, do you? It’s a triplet.
https://en.wikipedia.org/wiki/Triplet_lens


PostPosted: Fri Oct 20, 2017 9:16 pm    Post subject: Reply with quote

Sorry, it's just that I am a newbie in lens conceptions and disassembly.
Thanks for the link.

I should have precise my question : Is there a doublet group in the front element ? I ever broke a rear doublet group in a triplet lens, because I was not prepared to encounter a doublet group.



PostPosted: Mon Oct 23, 2017 6:08 am    Post subject: Reply with quote

Excuse me for becoming quite uninhibited but you are stubborn.
Despite the Wikipedia article with its drawings you presume more than three elements.
No, a triplet is a three-elements system. No doublets, no achromats, three separate, distinct pieces of glass

https://en.wikipedia.org/wiki/Cooke_triplet


PostPosted: Mon Oct 23, 2017 4:35 pm    Post subject: Reply with quote

I would not be stubborn if I had not experienced that : If I broke the rear glass of the Wollensak 6.5mm f/1.9 D-mount , it's because it has two joint glasses like in the Tessar and Heliar lenses. One of the two joint glasses broke in three pieces on the ground as I tried to catch it from falling.

Tessar : improved from the Cooke-triplet


Heliar : improved from the Tessar


I just want to be sure that Wollensak did not use Heliar structure in some lenses because if they did, I have to be more careful with the front elements.
And from the bad experience I had disassembling the 6.5mm, they could have.


PostPosted: Tue Oct 24, 2017 6:03 am    Post subject: Reply with quote

This thread is about a telephoto lens. Long focal length lenses almost invariably are of simpler design than normal and especially retrofocus wide angle lenses. A telephoto triplet does not need to contain an achromat. Different story with your 6.5 mm, please read about retrofocal designs. https://www.lensrentals.com/blog/2011/03/the-development-of-wide-angle-lenses/


PostPosted: Tue Oct 24, 2017 6:11 am    Post subject: Reply with quote

OK, thanks Wink