Film-Tech Forum ARCHIVE: Max wattage Lamps used for 35mm film..

This is topic Max wattage Lamps used for 35mm film.. in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Peter John Anthony. C (Member # 2500) on 10-21-2005, 01:04 PM:

Is it advisable to use 6k & 7K lamps for 35mm films for a large auditorium screen if needed???

What is the maximum wattage lamp we can use for a 35mm film.

If we are using a higher wattage lamps what all points we have to consider to maintain the tempreture of projection equipments.....

Thanks,
cheers

Posted by Steve Guttag (Member # 268) on 10-21-2005, 04:44 PM:

It really depends on the lamphouse/reflector in question as to what is the maximum lamp for 35mm.

I have successfully used up to 7KW on 35mm with Kinoton lamphouses without any observable damage.

On Christie lamps (SLC) when using a heat filter, running 6KW lamps will work but you will be slightly embossing the film (not to the point of blistering but observable heat damage when run over time). So far, no problem with Strong Ultra-80 running 6KW on 35mm film with a heat filter.

Posted by John Pytlak (Member # 331) on 10-21-2005, 07:25 PM:

It is very important to test for heat-related damage after you have aligned your lamphouse and checked your heat filtration. Run a loop of a trailer having very dark scenes for about 500 passes. Then carefully examine the film for any blistering, scorching, or embossing.

On a color print, severe heat damage will show as an opalescent scorch mark in the "hot spot" of the lamphouse focus. Using reflected light, it will appear magenta from the emulsion side, and yellow-green from the base side. Even if you have no scorch marks, severe embossing of each frame is indicative of excessive radiant energy, as it may permanently make the print difficult to focus.

Posted by Steve Guttag (Member # 268) on 10-21-2005, 10:08 PM:

Exactly...

After setting up these high-wattage 35mm systems, I run B&W test film with the 1.85 plate in a 10-foot loop...such as Schneider's CLT-2000 that is very black (a good way to end the life of a worn out loop)...check it after 10-15 minutes of continious running. If the 1.85 aperture es embossed onto the image...that is the type of radient energy you are putting on the film...Christie's SLC's consoles running 6KW with a heat filter will emboss the film under this test within 10 minutes of continious running (about 90 passes). A Kinoton Universal lamphouse with the 200x200 heat filter (and glass reflector) will not, even with 7KW running full-tilt..in fact, I've run 5KW on 16mm with the Kinoton. Strong's Ultra-80s seem okay, with a heat filter and lots of exhaust running 6KW on 35mm film. 5KW with an Ultra-80 I have a ton of experience with never a problem.

If you start to see any white flecks appearing on the screen when running B&W then you are actually scorching the film.

With any of the lamphouses listed above, if you tighten up the focus to the point of creating a hot spot, you WILL blister the film.

Everything has to be set up perfect to get the light through the film and not burn it up.

[ 10-22-2005, 08:59 AM: Message edited by: Steve Guttag ]

Posted by Peter John Anthony. C (Member # 2500) on 10-22-2005, 01:13 PM:

Thanks a ton Mr. Steve and Mr. John for your support...