Film-Tech Forum ARCHIVE: Substitute Lamphouse

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Posted by Al Chaney (Member # 794) on 03-15-2001, 02:36 PM:

Can some tell me is there a substitute
or replacement lamphouse (110 volt) I can use on my 35mm Century C projector. Can I use a slide projector or incandecent lamp as a replacament?

al wk:916-341-6233

Thank you forum members

Posted by John Pytlak (Member # 331) on 03-15-2001, 03:58 PM:

The optics of a 35mm projector are designed to have the film illuminated by a cone of light formed by an eliptical reflector that focuses the light of a carbon or xenon arc lamp just in front of the aperture. Since you would have to design a reflector for a standard tungsten lamp, your idea of using a slide projector to focus light on the film at the aperture should work for a small screen. An integral halogen lamp / reflector (e.g., FXL lamp) used in some AV projectors might work, but you may have difficulty getting it close enough to the film plane due to the shutter.
Best advice is to look for a used arc lamphouse, since a 5400K source is specified by standard SMPTE 196M anyway.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Paul G. Thompson (Member # 655) on 03-15-2001, 06:18 PM:

Years ago, ORC 1000 integrated xenon lamphouse was built that works with 35mm applications. It was small, compact, and self-contained. It simply plugged into a 120 volt receptacle. I am sure you can still find some around somewhere. However, be prepared to pay a hefty price for them. Last I heard, they go for about $1,000 or so.

Posted by Mark Gulbrandsen (Member # 72) on 03-15-2001, 09:09 PM:

Hi Al,
Any relation to Dick? What type of setup is this home, or theatre? At home you can get away with murder if you want to but as JOhn says the correct color temperature also has allot to do with it.
Mark @ GTS

Posted by Jeff Stricker (Member # 224) on 03-16-2001, 07:55 AM:

I have built a homebrew lamphouse using ENX 360 watt quartz halogen lamp and a condenser lens liberated from a photo enlarger. I had to do a bit of experimenting to determine the distance between lamp and lens : lens and film plane, but when finished I got great results (of course this is a home set up and, yes, the color temp. is off, but....). Also you will need a muffin fan to cool the lamp. This who effort set me back about $20.

Posted by Scott Norwood (Member # 30) on 03-16-2001, 09:12 AM:

Couldn't the color temperature be corrected with a gel on the port glass? Maybe John P. or someone else could post the exact number. I'm guessing that you want something like an 80A filter/gel, which is normally used on a camera when shooting film balanced for daylight indoors. You lose something like 2/3 of a stop, but it balances the light more toward the blue end of the spectrum (like xenon).

Posted by John Pytlak (Member # 331) on 03-16-2001, 11:08 AM:

To convert 3200K to 5500K, you would use a Wratten 80A or equivalent filter. But the light loss is almost 2 stops, so it will much harder to get a bright image.

If you can't find an arc light source for home use, I'd just use the tungsten-halogen lamp and settle for 3200K on the screen. In a darkened theatre, the eyes adapt quickly, and a slightly yellow highlight is preferable to having a dim picture.

Posted by Al Chaney (Member # 794) on 03-16-2001, 03:05 PM:

Thank you Forum Member for your help. I am running a home screening room (20'x 40'), curently running video. I am a Newbie and don't want to invest a lot of money until l learn more about the equipment. I have looked into the ORC 1000 and they are priced at $1200.00 as Paul stated. However, as mark mentioned I do want to get away with murder on the less than perfect projector while I am learning. I do have an old Holmes 8, with a lamphouse on it. Can the Holmes lamp house be used with my Century C projector. I welcome your comments and sugesstions for a substitute lamphouse.