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Topic: K19 on silver nitrate?

Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999

posted 07-20-2002 02:41 PM

OK, Gordon, I know this is going to take a left turn off topic here, but since you brought it up, let me put this to you: I am having trouble with one of the ORCON lamphouses in that no matter how well I seem to align and focus it, I can't get rid of a very distinct hot spot. I used the mechanical distance setting tool -- the one that sits in lens holder and passes the rod thru to the gate and sits on the bulb holder. The distance seems fine but the rod does seem like it has a slight angle to it. Problem is, this ORCON lamphouse and the Xetrons that I use at in the small theatre, they all sit on the pedestal base with the mounting holes all matching. However, the base has no adjustments whatsoever in the platform that the lamphouse is mounted on. There is no way to adjust the physical height or left/right orientation in relationship to the projector head. The lamphouses sit in a groove in the pedestal and the only thing you can do is make a gross distance adjustment toward or back from the head by way of the slots in the platform that holds the lamphouse locking screws. Even that is a bit silly because the mating cone of the lamphouse and the docking cone of the Century head don't have much leeway -- if you were to back the lamphouse off, even an inch or two, you would have this big gap spilling light between the lamphouse and the projector. So even though the lamphouse looks like you can set it at any distance you want (the screw slots are about six inches in length), only a single position will actually mate with the projector correctly and prevent light spill from the lamphouse.

This leaves only the three allen adjustments on the lamphouse -- the left and right mirror adjustments and the focusing adjustment. So far, no manner of adjusting these will eliminate that hot spot. And believe me, I have spent hours trying. I've followed the book about centering the round shadow so that no hot spot "peeks" out around it, but then when the lens is in, it is obvious that there is a hot-spot and the adjustments will move it side ways, up and down, but not eliminate it. The focus adjust will reduce it, but also that reduces the overall brightness. The second machine seems to give me very good brightness and almost no hot spot, but even this is not as even a light as I am used to getting from the old Peerless Magnarc.

So this is what I don't understand -- since the alignment of the lamphouse to the projector head is supposed to be so critical, how is it that there are no physical adjustments other than distance of the lamphouse to the projector head? The lamphouse and projector are sitting on a standard Simplex pedestal. It seems that the lamphouse platform is aligned to the projector head because when the lamphouse sits in the platform grooves, the two cones do meet perfectly.

I am assuming that xenon alignment is even more critical than carbon arc because with the Peerless, you just got the physical distance between the projector aperture and the lamphouse arc to 18in and that was all the physical adjustment you needed to do in the placement of the lamphouse on the pedestal -- any vertical or horizontal alignment was done by the fact that the lamphouse could only be screwed into one place on the pedestal platform -- same as with the ORCON and Xetrons. Once the Peerless lamphouse is sitting on the platform correctly you could get perfect end-to-end brightness simply by the mirror adjustments and the focus adjustment on the lamphouse.

So what other kind of adjustment can be made to this xenon lamphouse that will rid me of the hot spot? Is the pedestal not the correct base for this lamphouse? Should it have the ability to physically move the lamphouse in relation to the head -- up and down, left and right? Funny thing is, with a picture on the screen, the hot-spot was hardly visible. Yet, I want to get a much more even illumination than I am getting, especially since the second machine is putting out very good light with hardly any hot-spot.

Any help will be appreciated. If I am missing something very obvious, please be gentle.

Frank

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 07-20-2002 04:55 PM

Actually carbon arc alignment is also criticle and there were rod alignment kits and string kits for most. But the large plasma ball in the crater was more forgiving
Most bases have adjustment, the simplex is the least (except for the 3 and five point bases) but there is some left right adjustment and verticle adjustment
On one version it entails a excentric locking bolts
As for between the nose cone and the head just put a piece of stove pipe to fill in the gab if required

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