my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Kelmar Lens Turret ajustment

Author Topic: Kelmar Lens Turret ajustment Paul Vollmers Expert Film Handler Posts: 161 From: Sister Lakes, MI, USA Registered: Jul 2001 posted 02-22-2013 03:30 PM                     A friend of mine has a Century SA with a kelmar lens Turret. He has a scope lens, and a flat lens. The screen throw is about 25 ft. The scope lens fills the screen however when changing to the flat lens it is offset to the left by about 12 inches off center on the screen. Is there an adjustment of some kind to center both pictures on the screen? I looked up the manual on Film-Tech but there is no mention of centering both lenses? Any help here?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 02-22-2013 05:01 PM                        Yes. First determine which lens is correct and leave it alone. Use an alignment tool. Remember that the lens is NOT in the center of the film; it is offset by half the soundtrack width. When one lens is correct, project image and mark center of test chart on screen. Rotate to other lens and loosen the large allen screw that holds the lens clamping assembly for that one lens. Move lens so that centers agree and that is it. Louis  |  IP: Logged Paul Vollmers Expert Film Handler Posts: 161 From: Sister Lakes, MI, USA Registered: Jul 2001 posted 02-22-2013 05:55 PM                     Use an alignment tool....? What is that..? And how does one find the correct lens placement?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 02-22-2013 10:10 PM                        We had a long tube with a small hole in one end and a crosshairs in the other end mounted in a metal block shaped like a lens. Using a worklight in the shutter area, you could look down the tube. The goal was to have the crosshairs aligned with the center of the RP-40 test loop. Logical, right? The center of the lens is located in the center of the picture. (Be sure to realign the lamphouse after you get the picture on the screen.) Louis  |  IP: Logged Paul Vollmers Expert Film Handler Posts: 161 From: Sister Lakes, MI, USA Registered: Jul 2001 posted 02-23-2013 09:23 AM                     Louis, "loosen the large allen screw that holds the lens clamping assembly for that one lens". We are trying to figure out which large allen screw you are describing. And how it adjust the lens. Sorry for the confusion?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 02-23-2013 11:36 AM                        When you insert a new lens, you tighten 2 small allen screws in a clamping metal piece. The large allen screw is a pivot point for this clamping piece. I would agree that this looks unlikely, but its hole is oversize and it works. Louis  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 02-23-2013 11:36 PM                     Louis, while I agree that using the alignment tool is the 100% way of doing this, for the sake of discussion and since Paul is unlikely to have or be able to get said alignment tool, what procedure would you suggest? I am thinking of the following: Since the scope lens fills the screen properly (Paul: Is the illumination in Scope even across the full width of the image, i.e. the lamp is/appears to be properly aligned to the projector?) I would mark the center of the screen using RP-40. Then, without shifting anything else, set the turret to the flat lens and adjust the flat lens holder to proper center. Now, IF the flat image cannot be centered using the adjustment of the turret, then that means the Scope lens is also offset. If that is the case, I would then do this: Running RP-40, and with the turret in Scope, loosen the Scope lens adjustment. Turn the adjuster in both directions, noting the offset at each extreme. Then turn the adjustment to the center of it's travel, even if the image is not yet centered on screen. (Make sure the illumination remains uniform..if not, then the lamp will need to be re-aligned as well.) Now, shift the position of the PROJECTOR Console/base to center the image on the screen. Now, go the flat lens and center the image using the turret adjuster. I feel the above will yield acceptable results without going thru the expense of buying the alignment tool.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-23-2013 11:59 PM                       Before doing anything else, rotate the scope lens 180 degrees and see if the vertical center line changes. I had a pair of Schneider lenses that would move quite a lot. This made it impossible to get a common center line with flat lenses. I finally changed out the attachments and the problems went away. This particular set of lenses were quite eccentric.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 02-24-2013 07:01 AM                        Good point. Some lenses are slightly eccentric. (If very eccentric, I have seen Schneider lenses that had loose elements that, after they vibrated for a year or two, developed grooves in the side; they would not rattle. Reassembling the lens repaired everything.) Tony's procedure would probably solve the problem as described. Louis  |  IP: Logged Paul Vollmers Expert Film Handler Posts: 161 From: Sister Lakes, MI, USA Registered: Jul 2001 posted 02-24-2013 07:30 PM                     Okay........here what I did so far.....! I ran the RP-40 with the scope lens first, and found that the left and right edge alignments were pretty much where they were suppose to be equal. Then did the same with the flat lens....auto rotated it to the flat position and found the same left and right edge alignments for the flat position to be pretty close to be equal. However, when in the flat position the total picture is off to the left of center by 10 to 12 inches. I also loosened the flat lens, and rotated it 180 degrees, but the picture frame on the screen was the same, off to the left. I made no adjustments to the Turret as yet. So at this point I don't know if the scope lens is causing the problem or the flat lens, or both. Hope I made this clear........!  |  IP: Logged Victor Liorentas Jedi Master Film Handler Posts: 800 From: london ontario canada Registered: May 2009 posted 02-24-2013 08:03 PM                     One thing I always do is rotate the scope lens 180 degrees and compare focus both ways...it's almost always different. One usually better than the other. Since you may not have the alignment tool to get a perfect optical center...I would get the best scope image possible and then adjust the flat lens to agree with it.If flat focus sucks then you have more work to do but it's a good starting point.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-25-2013 12:53 AM                       The scope lens is way more likely to be eccentric or out of round than the flat. First, any out out roundness is magnified by 2 and the lens is longer and more complex. I did say scope in my earlier post, right?  |  IP: Logged Paul Vollmers Expert Film Handler Posts: 161 From: Sister Lakes, MI, USA Registered: Jul 2001 posted 02-25-2013 06:08 PM                     Yes, Sam, you did mention the scope lens. So today I rotated the scope lens 180 degrees and looked at the picture on the screen and found that it was the same frame size and location. It's like the very front of the flat lens needs to go a tad to the right, to center the picture on the screen to make it uniform ( equal) on both sides of the screen. I have a 65mm scope Schneider, and a 42mm flat Isco lens. They both have the same space upper and lower on the screen.  |  IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.