This is topic Port glass Problem need help in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Brooks M. Davies (Member # 1349) on 07-13-2002, 02:39 AM:
My question is about cleaning the port glass, our 14 plex has a tint on our port glass, yes tint, pretty dark too, anyway when cleaning the glass it leaves streaks. I have tried every glass cleaning method i have ever heard of in reducing the streaks, yet still they are there. It registers fine on the light meter, even with the streaks, and im not sure if it can be see on screen, I cant anyway, but has anyone seen this or dealt with the "tint that cant be clean"? ive tried all the port glass cleaners there are and windex, vinegar you name it any secret potions out there??
thanksits the glass that is tinted not a stuck on tint just thought id throw that in.
Posted by Daryl C. W. O'Shea (Member # 1303) on 07-13-2002, 02:44 AM:
Run a search (link at top of page) for search words: napkins and user: Brad Miller. You'll find lots of info in the resulting thread.
Posted by Steve Kraus (Member # 476) on 07-13-2002, 01:56 PM:
OK, I give up: Why is the glass tinted? And since that is SO wrong why should we care about cleaning it as opposed to replacing it?
Posted by Bruce Hansen (Member # 281) on 07-13-2002, 04:45 PM:
Is the "tint" an anti-reflective coating?
Posted by Paul G. Thompson (Member # 655) on 07-13-2002, 07:41 PM:
I would guess the tint is the coating to increase the efficiency of light passing through it, just like a projection lens.Ammonia works well, but your nose might not like it. However, I don't know if it will damage the coating.
I have seen someone really saturate the window with rubbing alcohol and wiped it down with soft lint-free towels. Again, then the window was generously re-saturated and a squeegee was used to finish the job.
I was amazed with the results.
Posted by Frank Angel (Member # 248) on 07-16-2002, 01:03 AM:
Darkly TINTED port glass? Or is that - Through a Tinted Port Glass Darkly? I am with Steve on this -- the proper way of dealing with tinted port glass is the same as what you do with dead Xenon bulbs. You take the port glass out carefully, wrap it in heavy newspaper and place it in a heavy duty plastic bag, put it in a garbage pail and smash it with a hammer.
And THAT's what you do with tinted port glass.
Seriously....when you look THROUGH it, does it look tinted? A coating like you find on a lens is deceptive -- the color that you see while looking AT the lens surface is the coating affecting the light bouncing off it -- when you look THROUGH the lens, you don't see any color at all -- it becomes obvious that the lens glass has no tint and is clear. If you look through the port glass and you see that the screen looks anything but pure white, then take the steps outlined above.
Frank
Posted by Patrick McDonough (Member # 1363) on 07-16-2002, 07:10 AM:
I couldn't imagine using tinted port glass. I would think it would darken the picture.
Posted by Carl King (Member # 398) on 07-16-2002, 07:41 AM:
How old is the 14-plex. If the port glass is new it may have a protective coating on it. I could be wrong but I seem to recall the
port glass in my 7-plex having a green coating on it that the installers removed. I'll check with my tech guy, "Sparky".
Posted by Brooks M. Davies (Member # 1349) on 07-17-2002, 03:52 AM:
ok to answer the questions yall had, its not a surface tint its tinted glass and it is def. tinted. looking out into the auditorium with the overhead cleaning lights on, you can def. tell. kinda like a car window tint yet not stuck on, i dont think its a reflective coating as we can see the picture on the port glass and it reflects back in to the booth, and you can even watch some of it off that wall, the theater is a "hollywood" wallace 14 all staduim seating about 3 years old, yes only 3 years old ,when put up to the meter it registers ok just dont understand the tint myself and its a bear to clean, but the mcdonalds tip from brad works pretty well. yes im stumped......
Posted by Brian Tristam Williams (Member # 1235) on 07-17-2002, 07:13 AM:
I would think that the reason to have tinted portholes is because it looks cool 
. Also, it is increased security against booth-jackings. 
Posted by John Pytlak (Member # 331) on 07-17-2002, 12:50 PM:
Measure the screen luminance both with the port glass in place, and then without any port glass. If the reading with the port glass is more than about 1 footlambert less than without any glass, you are losing too much light.Likewise, compare the stray light just to the side of the screen with and without the port glass. In a totally darkened theatre, briefly project "open gate" white light on the screen, and observe the amount of stray light that can be seen on a white piece of cardboard held near the screen, just outside the projected beam. Remove the port glass, and see how much less stray light there is. (Don't project "open gate" more than a few seconds at a time, to avoid damaging the lens with excessive heating).
Anti-reflection coatings on clear optical-quality glass are well worth the additional expense compared to plain glass.
http://www.kodak.com/US/en/motion/newsletters/pytlak/dec99.shtml
------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
Posted by Frank Angel (Member # 248) on 07-18-2002, 06:15 AM:
Definately if the glass is reducing the light output to the screen as John says, it has to go, but even if you don't read a significant drop, if it is imparting an color change, i.e., adding color (actually subtracting color) to what should be the pure white light of the xenon, then get rid of it, that is if you can convince management that they have been living with a mistake all this time -- that might be a lot harder to do than just swapping two pieces of glass!
Posted by William T. Parr (Member # 677) on 07-18-2002, 07:53 AM:
Brooks, What you may have in booth for glass, is called Maltese Parallel Lens. I have it in my booth at the Highland and I have no problems with it. Although it is not tinted, it does have a look to it that makes it look tinted. I have had great sucess cleaing mine with lens cleaner and brown paper towles or newspaper with no streaking.
Posted by Gordon McLeod (Member # 33) on 07-19-2002, 09:47 AM:
Another possibility is that it is heat tempered glass and in some cases local fire deptartments require its use whenever a fire wall is pierced with no fire damper.