Film-Tech Forum ARCHIVE: glass and angle

This is topic glass and angle in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Anhtu Vu (Member # 7689) on 10-02-2015, 08:24 AM:

I need to change the glass for my projection window. Any recommendations ? Ideally in the montreal area. And how about the ideal angle ? thx

Posted by Rick Raskin (Member # 1561) on 10-02-2015, 10:50 AM:

Tilt it so it puts reflections onto the floor.

Posted by Sam D. Chavez (Member # 1841) on 10-02-2015, 01:29 PM:

Floor of audience or booth? Can't be too careful with someone who posts multiple times on the same question.

Posted by Rick Raskin (Member # 1561) on 10-02-2015, 04:00 PM:

Good point.

Posted by Mark Gulbrandsen (Member # 72) on 10-02-2015, 05:04 PM:

There IS actually a spec for this as far as maximum and minimum tilt is involved. I was involved with some Goldberg ports way back when and they did track down a recommended spec for it. Not sure if it was SMPTE or Kodak or who the heck wrote the spec, but one does exist.

Mark

Posted by Anhtu Vu (Member # 7689) on 10-02-2015, 09:15 PM:

So strange as i've gotten so many different suggestions/recommendations from professionals on this topics.

I'm setting up a mix room for a friend with a Barco 4K, we tried both tilted and non tilted glass….no difference. The non tilted arrangement did not produce any ghosting…

Mark…do you know where i can find this SMPTE document ?

Posted by Marco Giustini (Member # 4544) on 10-03-2015, 06:04 AM:

if it's a single glass, it should not produce ghosting. If you have a double glass, parallel sheets WILL produce awful ghosting.

It's always nice to tilt it a little anyway, to avoid possible reflections from the lens or the 3D device, if any.

Posted by Paul Mayer (Member # 355) on 10-03-2015, 04:07 PM:

I don't remember the exact number, but it's called the Brewster Angle. Laser guys know about it. Do a Google search on things like Brewster Angles and the US Bureau of Radiological Health laser standards...