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TOPIC: Bulb too hot?

Bulb too hot? 22 Jul 2007 20:04 #22542

  • BurneyFalls
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I had a print several years ago that was really dark throughout the film. After a few showings I saw small white spots on the screen. It got worse every showing. As I recall, the print process was different for that movie, because of its extremely dark scenes.

I am again seeing this on a print now, but only in the really dark scenes. I will check my bulb gauge readings tonight.
Any one else experience this? Any suggestions?
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Re: Bulb too hot? 22 Jul 2007 23:54 #22543

  • rodeojack
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Yep, you're burning holes in your film. You've either got your bulb focused too tightly (one major hot spot in the center), or you need heat filters... maybe both.

It's not recommended (John Pytlak has a lot of info on this), but I've had lamphouses that have run 4,000 watts with little-to-no filtering. Perhaps I had poor reflectors and you have great ones.

In any case, check your bulb focus immediately. It probably needs to be widened out some. Any damage you've done sofar is permanent.

Incidentally, the damage will occur in darker scenes, as the dark emulsion absorbs more heat than light/clear scenes.

[This message has been edited by rodeojack (edited July 23, 2007).]
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Re: Bulb too hot? 23 Jul 2007 10:26 #22544

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The spots are not centralized in any one location, but dispersed throughout the screen, similar to, but not nearly as many as the black with white spotted background on this website. I will adjust the bulb back immediately. Thanks for the reply.
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Re: Bulb too hot? 23 Jul 2007 17:09 #22545

  • rodeojack
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If you think it's already adjusted pretty well, you might want to have it looked at. You didn't say what your wattage is, but I think John said you could go up to 2,000 watts without heat filtering. Still, a Super Lume-X with an UltraFlat reflector might be a problem, as the Ultraflat process does not have heat filtering and throws literally everything forward.

I have 7,000 watt lamps here, with dichroic reflectors and heat filters behind the snood. I have no problems if I take the time to adjust a new bulb in (which I do... now). However, my first night with the first new lamphouse included some pretty interesting special effects on the screen... a LOT like the background on this forum!
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Re: Bulb too hot? 24 Jul 2007 20:12 #22546

  • John Pytlak
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Heat damage will often first be seen on the color print itself as a opalescent discoloration when viewed by a bright reflected light. It will look like magenta-colored spots from the emulsion side, and like yellow-green opalescent spots from the base side of the print. This is caused by the heat causing a separation between the emulsion layers of the print. As the damage progresses, you will sometimes see a "snowflake like" or spiderweb pattern in the darkest areas of the print (because they absorb the most heat), eventually, breaking out into colored or clear spots or even charring.

It is HIGHLY advised that any lamp over 2000 watts use some form of dichroic infrared heat filter. Lamp alignment and focus should be immediately checked, and the focus should be "backed off" so as to spread the light evenly over the full frame, and not "hot spot".

Silver-image B&W prints are even more prone to damage than color, as they absorb almost all the additional infrared heat energy, and not only the visible. Damage may first show up as a blister or charring.

Heat issues also affect focus stability, as the film "buckles" and deforms from the heat, and may show soft focus

John P. Pytlak, Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: +1 585-477-5325 Fax: +1 585-722-7243
E-Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Website: http://www.kodak.com/go/motion

[This message has been edited by John Pytlak (edited July 24, 2007).]
John P. Pytlak, Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: +1 585-477-5325 Fax: +1 585-722-7243
E-Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Website: http://www.kodak.com/go/motion
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Re: Bulb too hot? 25 Jul 2007 00:46 #22547

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This is a 2000w bulb in a Xetron. The damage is not in every scene, not even in every dark scene. The credits are fine, as are all the trailers. Most of the movie itself is fine also. I adjusted the bulb back a little yesterday.

I have a new reflector that I ordered awhile back. We couldn't figure out how to install it earlier, but talked to Neumade today and should be able to put it in this weekend. Will that even help--or make things worse?

I will give the print a good inspection when I tear it down this weekend.

Even though I only have a 2000w bulb, should I install a heat filter? How do I do that?

Thanks for the replies everyone. Nice to see you on-line, John. Hope you are feeling better.

[This message has been edited by BurneyFalls (edited July 25, 2007).]
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Re: Bulb too hot? 25 Jul 2007 19:22 #22548

  • John Pytlak
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As long as you can back off the focus to the point there is no "hot spotting", and the print damage stops, you should be able to do without having to purchase a heat filter. With only 2000 watts, damage can usually be eliminated by proper alignment and focus of the lamp.

John P. Pytlak, Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: +1 585-477-5325 Fax: +1 585-722-7243
E-Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Website: http://www.kodak.com/go/motion
John P. Pytlak, Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: +1 585-477-5325 Fax: +1 585-722-7243
E-Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Website: http://www.kodak.com/go/motion
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