Film-Tech Forum ARCHIVE: Bulb out of focus or do I need to.....

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Posted by Justin McLeod (Member # 1329) on 09-25-2002, 01:55 AM:

I have a bulb on a Christie that seems to be out of focus. The Image on screen is bright in the center but dark on the outside. This Christie projector does not have a auto focus feature I think. I dont know how to focus a projector bulb either,especially the ones in a Christie.

Now on the other hand, the charts for the bulb replacement's ( for this projector ) say it need's to be changed out. It will be a year old next month.

I really need some help.

Posted by Brad Miller (Member # 2) on 09-25-2002, 02:06 AM:

What is the model xenon lamp? How many hours has the bulb acquired since it was installed?

Bulbs don't suddenly go out of focus like that. Even if this was something you have seen for awhile, xenons burn the other way, such that the light will get more spread out, not more condensed in the center of the picture. Someone has jacked with the controls on the unit.

Get your lamphouse manual out, or download the one here. In there it shows where the controls are to adjust focusing. It is definitely focused down too tight. Regardless, if it has indeed been a year since the last bulb change, odds are it is severely over hours and needs to be changed out. Contact your tech to handle the new xenon bulb installation.

Posted by Manny Knowles (Member # 1171) on 09-25-2002, 10:43 PM:

I just dealt with this very issue. It only seriously affected my scope image. It turned out to be a three part problem.

* Bulb focus and alignment - wasn't too bad but we improved the light output somewhat
* Cooked lens - probably from too many tail-outs without automated shut-down. Changing the lens had a dramatic impact.
* Scope adapter "tube" was too long and caused vignetting around the corners of the image. This could resemble what you are describing.

Posted by Justin McLeod (Member # 1329) on 09-26-2002, 04:15 PM:

Everything seemed to work fine a week ago. I really wont know anything more until I figure up the hours on the bulb to date and learn how to focus the bulb. I think that when that happens I will figure out if its a lense problem. I hope its not a cooked lense. I will switch flat with scope and see what happens, if it is a cooked lense. It's a flat feature that this has occured on.

I do know the automation has been failing on this projector,and sometimes I been having to manually raise the douser and shut off the slide machine and sometimes the sound wont be heard with the start of the trailers.

Posted by John Pytlak (Member # 331) on 09-26-2002, 07:42 PM:

Justin wrote: "sometimes I been having to manually raise the douser "

Are you sure the douser is not blocking part of the light? Sounds like you have lots of maintenance issues that need attention from your technician. Those accumulating problems may be driving away some of your audience.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Justin McLeod (Member # 1329) on 09-26-2002, 08:30 PM:

I can tell when the douser is not up all the way or when its not up at all. The problems on this projector are for one of our four smallest screens.

I will have more info on this problem after work friday to share with you all.

Posted by Justin McLeod (Member # 1329) on 09-28-2002, 02:16 AM:

I did a lense changeover today and its the same thing of both flat and scope but we have been running flat features with this projector for over a month now. I really think the buld is out of focus and needs to be replaced.

Posted by Brad Miller (Member # 2) on 09-28-2002, 02:25 AM:

Justin, crack open that manual to your lamphouse. We cannot help you because you have not even told us the model of your lamphouse. Focusing the bulb is relatively easy. Instructions on how to do it are in the manual. Bulbs are too expensive to just randomly go changing them out whenever the light isn't good. Besides, a brand new bulb you put in there may line up and give worse light. Then there's the fact that changing out a bulb is more troublesome than simply focusing it. Read that manual.

Posted by Michael Rourke (Member # 1142) on 09-28-2002, 12:13 PM:

I have had a bulb lose focus due to the focus adjustment springs needing to be replaced. Justin, if you don't know how to adjust a lamp, then I assume that you don't know how to replace bulbs either, since it is nearing the end of the rated bulb life I would get your tech to change the bulb and focus it, during the focusing he will be able to tell if the up/down, left/right, in/out adjustment springs need to be replaced. After changing the bulb and refocusing if the problem still exists then it's probably the lens.