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

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Uncrisp image (Page 1)

This topic comprises 2 pages: 1  2

Author Topic: Uncrisp image Peter Mork Expert Film Handler Posts: 181 From: Newton, MA, USA Registered: Jun 2002 posted 01-16-2005 09:08 PM                     A conundrum. I run two side-by-side houses, #1 and 2, that are virtual twins. Same screen size, same throw. Both have straight-gate Century C's, seemingly in good mechanical shape with steady pictures, both have the same 2000w Strong lamphouse. But the image in #2 is noticeably inferior to #1, especially apparent when running scope. It's not really a focus problem: focus is consistent across the screen in both houses, but #1 seems crisp and clean and #2 looks smeary around the highlights, like looking through a dirty window. I'm thinking it's a dirty, damaged or just plain inferior lens, but I swap lenses between the cinemas and the problem stays put, with #1 crisp and #2 muzzy. (Porthole glass in both is as clean as I can get it. Also, I've run the same print in both houses and seen a difference, so it's not like I'm comparing apples and oranges.) Anyone got any bright ideas? I am stumped, and that NEVER happens y'know.  |  IP: Logged Paul Mayer Oh get out of it Melvin, before it pulls you under! Posts: 3836 From: Albuquerque, NM Registered: Feb 2000 posted 01-16-2005 09:18 PM                        Shutter opened a hair too wide? Could cause just enough symmetrical travel or shutter ghost to give a slightly smeary appearance. I'd like to see "Uncrispitude" added to the official list of SMPTE terms.  |  IP: Logged Peter Mork Expert Film Handler Posts: 181 From: Newton, MA, USA Registered: Jun 2002 posted 01-16-2005 10:25 PM                     Nope, it's definitely not a travel ghost thing. The problem's more of an overall dinginess or lack of contrast.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-16-2005 10:29 PM                     ...check your mirror focus..you could have a slightly warped mirror that is throwing off the light temperature spectrum or even the focus. Strongs, with their weak air travel inside and the way the mirrors are made and shaped are good for overheating. Course, is this a Super Lume-X or a X-90 console? thx and good luck with this. I know this can be frustrating at times - Monte  |  IP: Logged Peter Mork Expert Film Handler Posts: 181 From: Newton, MA, USA Registered: Jun 2002 posted 01-16-2005 10:37 PM                     It's a Strong X-90. But I don't get how mirror focus could cause the problem. Doesn't seem to be running extraordinarily hot. I should mention I recently changed the lamp and had the same problem with the old, relatively dim bulb as the new, much brighter one.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-16-2005 10:57 PM                     ..it could be that the back part of the mirror could be just slightly warped, which one really can't see until you take that mirror out, lay it face down and place a straight edge across the rear opening, then you can see the warpage. Usually was due to a bulb that was slightly sitting just slightly too far back and heating up the rear quarter of the mirror. Is the backside of the mirror darked by getting too hot, which could easily happen with a stack fan going out and being out for quite a while? I should send you a pict in this area of a good warped mirror, which looks good from inside, but you should see the warpage at the back of the cone. I had a horrible time getting some decent light out of this one, which was remedied with a mirror replacement. thx-Monte  |  IP: Logged Peter Mork Expert Film Handler Posts: 181 From: Newton, MA, USA Registered: Jun 2002 posted 01-16-2005 11:03 PM                     Hm, I shall take a look at that and report back. There were times when the fan below the mirror got clogged with dust and didn't turn for who knows how long.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-16-2005 11:13 PM                     quote: Peter Mork fan below the mirror got clogged OUCH! that'll heat up a back end of a mirror for sure. That fan that cools down the bulb contacts, and with the channel that the air has to travel through to do both ends, was a poor design in my book for the end cooling practice. There must have been some air to travel to keep the cathode's failsafe switch's "sailfin" in the "on" positition (unless the switch has been bypassed...), but still not enough to kelp cool down the rear end of the mirror. You must have an older version of the X-90 lamphouse (the one without the muffin fan that blows on the anode of the bulb), like I have. good luck once again. - Monte  |  IP: Logged Peter Mork Expert Film Handler Posts: 181 From: Newton, MA, USA Registered: Jun 2002 posted 01-17-2005 12:19 AM                     I didn't see any obvious blackening or warping of the mirror. My screen illumination is fairly even. I still don't understand how any lamp issue could result in the problem I described, unless perhaps it got the film so hot that it caused it to buckle in the gate, but I don't think that's happening...  |  IP: Logged Wolff King Morrow Master Film Handler Posts: 490 From: Denton, TX, USA Registered: Feb 2004 posted 01-17-2005 02:08 AM                        Is there any way you could remove your port glass just to make sure its not an impurity in the glass? Might be worth checking after close just to conclusively rule out the glass. Also, do you have UV shields? I once had a minor blurry problem that I discovered was from someone having smudged the UV shield.  |  IP: Logged Adam Martin I'm not even gonna point out the irony. Posts: 3686 From: Dallas, TX Registered: Nov 2000 posted 01-17-2005 02:34 AM                     PLEASE EDIT YOUR ORIGINAL POST AND CHANGE THE NAME OF THIS THREAD TO SOMETHING USEFUL  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 01-17-2005 09:50 AM                        quote: Peter Mork My screen illumination is fairly even. I still don't understand how any lamp issue could result in the problem I described, unless perhaps it got the film so hot that it caused it to buckle in the gate, but I don't think that's happening... All else being equal, lamp alignment could affect optical flare. Simplistically, if the cone of light is not on the optical axis of the lens, or is overfilling the entrance pupil of the lens, you could have some light "bouncing" around inside the lens, causing an increase in flare light.  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 01-17-2005 10:43 AM                    I've always wondered if a sub standard (or dirty or whatever) screen could cause this.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 01-17-2005 11:06 AM                        quote: Mark J. Marshall I've always wondered if a sub standard (or dirty or whatever) screen could cause this. Usually, a dirty or stained screen will reduce the light level, or change the color temperature of the reflected light. If the screen material (often vinyl) did not have pigments in it, it could theoretically "light pipe", which would cause a halo around light objects. Or you might be able to see a reflection of a light or shiny surface behind the screen through the perfs.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 01-17-2005 11:16 AM                        I know it's a bit of a faff removing the lamps, replacing them and refocusing the mirrors; but swapping the mirrors would either identify or rule that out as the cause of the problem, once and for all. Also, do you have any heat filter glass in the lamphouses?  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1  2

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.