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Author Topic: Light efficiency with 62.5 mm v/s 70.6mm diam. lenses Jerry Axelsson Expert Film Handler Posts: 107 From: Stockholm, Sweden Registered: May 2005 posted 07-08-2012 05:11 AM                     Is there any difference in light output/efficiency in a modern 35mm projection lens (3-5 years old). If you compare the same lens model in a 62.5 mm diameter version and a 70.6 mm diameter version?  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 07-08-2012 07:16 AM                     I have found next to none differences in most lenses since the glass is manufacturered in modular form to fit as many situations in their product line. I see the same situation in some camera lenses we service....many common metal "plumbing" parts to make an end product.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 07-08-2012 08:23 AM                     It is only going to make a difference as you approach 140mm EFs. Schneider and ISCO's lenses below 100mm (and for ISCO above 40mm or so) are identical with respect to 62.5 and 70.6mm. The outer most lens barrel (hollow) is all that is different. On lenses like the Kiptar...unscrew the outer most silver sleeve and you will have a 62.5mm barrel on the inside.  |  IP: Logged Jerry Axelsson Expert Film Handler Posts: 107 From: Stockholm, Sweden Registered: May 2005 posted 07-08-2012 09:04 AM                     Thanks for the info guys.  |  IP: Logged

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