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Author Topic: Focusing scope lenses issues John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 12-17-2005 09:39 PM                     Frank, I think you misunderstood Woody Allen. I believe he is saying that because white credits on a black background absorb a lot more heat than the rest of the film, they are much more likely to be subject to embossing, and thus to have a different focus point than the rest of the film. --jhawk  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 12-19-2005 10:14 AM                        I recall a recent B&W production with silver-image prints had intertitles that alternated between white letters on a black background, and black letters on a clear background --- the focus difference due to varying levels of curl from the radiant energy absorption was quite noticeable, especially on larger screens with large lamps and short throws (less depth of focus). Despite numerous Kodak publications, people sometimes forget how much more radiant energy silver-image B&W prints absorb.  |  IP: Logged System Notices Forum Watchdog / Soup Nazi Posts: 215 Registered: Apr 2004 posted 01-23-2009 06:00 AM                 It has been 1130 days since the last post.  |  IP: Logged Justin Hamaker Film God Posts: 2253 From: Lakeport, CA USA Registered: Jan 2004 posted 01-23-2009 06:00 AM                        Not sure if this is the correct thread to post this or not, but I've always had issues getting a sharp focus in scope on one of my houses. Tonight when I was playing around with it, I realized the scope lens comes apart into two pieces, one of which looks like our flat lenses. I also realized there was a ~1" ring that appears to have been removed from the lens - it's been laying around since I came to this theatre and I never knew what it was for. Just for grins, I put this piece between the two other pieces. When I put the reassembled lens in place and ran a test loop, I was able to get it focused better than I could ever remember. Does this sound correct? For what it's worth, it's a Schnieder(?sp) lens.  |  IP: Logged Jonathan Althaus Master Film Handler Posts: 435 From: Bedford, TX Registered: Dec 2008 posted 01-24-2009 12:27 AM                     Sounds like the throw adjustment. We had one Schneider scope lens never focus, turned out someone had adjusted the throw, and that was the whole cause.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-24-2009 01:03 AM                     . That 1" ring mentioned is for your focal length between the "prime lens" (what you mentioned as the 'flat' lens), and the attachment that is set for your location there. With you adding it, it lengthened the distance from the prime to the attachment so the attachment adjustments could be made better. You oughta see scope lenses for drive-ins: a pretty long lens due to the length of spacing inbetween the prime and the attachment since they got a super long focal length. By lengthing the distance, it keeps the light within the glass elements inside the attachment itself instead of flooding against the side of the attachment barrel when leaving the front lens - prob why you were having focus issues. Kinda image an "X" with the middle of the "X" being the back of the lens. the right legs of the "X" has to pass through the lens without touching the inner walls of the entire lens barrel - why of these spacers..  |  IP: Logged

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