Film-Tech Forum ARCHIVE: Xenon Lamp House Focus with Christie P35C. Seeking Advice.

This is topic Xenon Lamp House Focus with Christie P35C. Seeking Advice. in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Alan Gouger (Member # 543) on 06-17-2008, 03:19 PM:

Hey guys. I have three lamp houses and Im having the same issue with all three. Maybe this is normal and Im expecting to much which is why Im seeking the help from those with more experience.
For a projector I am running a Christie P35C. Of the 3 lamp houses I have a vertical Christie, a small Kinoton and a ORC.
What I am questioning is uniformity. Im having a very hard time getting anyone of these to give anything close to a uniform brightness pattern with 1.85. Scope looks OK but open gate no film flat looks as if I am not filling the entire 35mm aperture as the corners & L/R side of the screen really dim compared to the center. I thought pulling the lamp house further back will increase the size of the light beam but it results in just the opposite. Butting each lamp house right up to the projector gives the best results but again I still have the dim corners. Ive tried to defocus the lamp to help spread out the light but then its to dim.
Is this normal. Nether of the LH have that negative lens. Is that a requirement and why I am seeing what I am seeing? Watching a film it is not as noticeable but because I am aware of how bad it looks without film it is bothering me but maybe I am striving for something not possible hence this post. Using my incandescent lamp house from my DeVry with its 1000 watt lamp & condenser lens yields far better uniformity but the light output just does not cut it for flat films.
For the most part I am running low wattage lamps...500 and 800watts.

Any suggestions appreciated. Thank you.

Posted by Louis Bornwasser (Member # 3063) on 06-17-2008, 06:25 PM:

Other than the vertical Christie, we still don't know exactly what model you have. Depending on vintage; you could be very good or very bad.

Prescription: take (1) Super Lumex or Christie SLC and call me in the morning. You will be amazed. Louis

Posted by Richard Fowler (Member # 893) on 06-17-2008, 06:33 PM:

Most lamphouses do not give a 100% flat field due to reflector design. Projector lens can be a factor either f speed not matching reflector or wide angle short throw lens creating an increased hot spot. The ORC is more matched for a fast f speed lens, may need an correction spreader lens in the snoot based on your model. The BF type vertical Christies also had a limited adjustment range with a hot spot "fix" sometimes (via a strip of metal or "dot") required in the snoot. the baby Kinoton lamphouse had optional auxilary condenser lenses in the projector to even the field but may not fit your projector.
So many answers.....but more questions need to be asked (lens, throw, screen surface, screen mounting, specific model of lamphouse et cetera) [Smile]

Posted by Jack Ondracek (Member # 1466) on 06-17-2008, 06:59 PM:

I may have missed a model, but the only Christie I ever saw with a vertical bulb was the BFD16, a horrible excuse for a lamphouse; seemingly designed specifically to keep at least 50% of the available light within the cabinet.

No ORC lamphouse is worth the space it keeps on a shelf... except possibly as an emergency spare of last resort. Their designs weren't very efficient, either... though maybe just a bit better than the Christie.

That would leave your Kinoton as the only possible choice for a decent lamphouse... I've never seen one.

Posted by Alan Gouger (Member # 543) on 06-17-2008, 07:58 PM:

The ORC model is 7100. It takes an external PS. The Christie is a BF5L.

No model on the Kinoton but here is a pic.

Posted by Mark Gulbrandsen (Member # 72) on 06-17-2008, 08:23 PM:

In my pile(literally) of old verticle lamphouses out in my garage which are mostly Shakamecannica I have a Christie BF-5L and I'll state that you'll never get even light out of it. Believe it or not at home though it makes a great 70mm lamphouse. Focus the lamp way way back and it actually gets pretty darn even... Used one for yuears to project 70mm at home and the light is also extremely cool with the lamp set this way. The only reason I'm saving these lamphouses is because of scarcity of mirrors and I have some Phillips FP-56 machines machines that have barrell shutters and the only zenons that'll work half way decent are verticles.

Louis's solution will cost you megabucks but at least for once he is right! For practical proposes you need to get or aquire an ORC 1000 and set it up very carefully. Its not only economical to operate but if very carefully set up IT CAN meet or come very close to meeting uniformity specs on a smallish 10 to 15 foot wide screen but no larger.

Ahhh, so I see you have the "Ben Vista Unregestered Version" of the Knoton lamphouse.... Ooookahhh....

Mark

Posted by Tim Reed (Member # 137) on 06-18-2008, 01:12 AM:

quote:
Louis's solution will cost you megabucks but at least for once he is right!

'For once'?! To paraphrase the poet, Louis has forgotten more than you'll ever know, you arrogant @#$&*!.

Posted by Mark Gulbrandsen (Member # 72) on 06-18-2008, 07:50 AM:

quote:
Louis has forgotten more than you'll ever know,

How would you know that??? Its highly likely that Louis and I have forgotten the same amount but you sure make it clear that you've forgotten everything!

Posted by Richard Fowler (Member # 893) on 06-18-2008, 08:06 AM:

They both have using the same synthetic oil to slow down the effects of gummy gear deposits in the brain [Wink]

The baby 500 watt Kinoton was designed to hang on the shutter housing on a FP type of machine and use the optional recommended
condenser near the gate.

Posted by Alan Gouger (Member # 543) on 06-18-2008, 09:09 AM:

Who would sell condenser or negative lens?

Thank everyone.