Altman Comet colorframe problem

[Max]

Long time lurker, first time poster
I am a student at a school that is doing a play. My TD has other things to do like focussing and geling to do, and as I am appointed "Spotlight manager" he tasked me with fixing the problem.
We have Altman comet followspots that work, but, on the gel boom, if you use a frame that is farther away from the first lense, soime of the light "misses the gel. this causes a blotch of uncolored light. I have affixed a photo of my hand in front of the gel behind the 2nd lens, you should be able to see my problem.

If somone could tell me how to fix it that would be appreicated.

ps: I can take more pictures upon request
PPS: when image uploladed it got flipped

 

[derekleffew]

I can't remember ever actually using a Comet, but I'll take a stab at your problem. Is frame #6 (closest to the stage/PNK handle) moving the same distance as frame#1 (closest to the lamp/RED handle)? That is, is the color boomerang working correctly? Might something be somehow preventing the farther frames from being fully engaged?

I can't imagine the light would spread that quickly in the ~3" of throw distance, but what if you made the "frame" bigger by adding some blacktak around the outer circumference? You'd mask the "blotch of uncolored light" and shouldn't interfere with the optics, but if a dark spot is visible in the pool onstage, there's an optics problem someplace.

I think you said you have multiple fixtures. Are they all doing it? I'd usually add to check the bench focus, but since the unit uses an MR16 lamp where the relationship of filament to reflector is fixed, there's no adjustment there. But is the lamp seating fully in its holder?

In case you don't have it, here is the Altman Comet Parts Manual/exploded diagram:
http://www.altmanltg.com/altman-lig...followspot/Comet-Followspot-Parts-Diagram.pdf . There is really no User Manual.

 

[Les]

The Comet's boomerang isn't terribly unlike the 1000Q boom except this has that self-cancelling feature. The only things I can think of is that the self-cancelling mechanism isn't holding the frame at the proper height; the frame's arm somehow got bent; or that the boom isn't seated in the fixture correctly. There should be a weather striping-like material forming a gasket between the boom plate and the barrel of the fixture. Make sure that's still present. Otherwise, it's hard to tell without seeing a video demo or the entire unit pulled from the fixture. How does the pool on stage look?

You could also cut the gel just slightly too large if you are unable to come up with a fix.

 

[derekleffew]

... You could also cut the gel just slightly too large if you are unable to come up with a fix.

That's brilliant, and a much better idea than my Blacktak solution. Still it's only treating the symptom and not the disease.
.

 

[Max]

Yeah just the self canceling mech does not work, I can get pics but you'l have to wait ~35 mins
I will take one of the pool and one of the boomerang assembly for you(Les).
Thanks

 

[ccm1495]

We have two Altman comments that we use on a regular basis. I have found that when the fixture is used at the extremes of its zoom it is prone to light leaks. Im also thinking that if your frame holder is broken and spring no longer functioning your gel frames may be traveling too far and coming out of the top of the light beam.

 

[Les]

Aw shucks, thanks derekleffew.

Thanks in advance for the pics -- if we can fix that self-cancelling mechanism, I'd be surprised if that didn't help the alignment issue as well. Many Altman spots do have some adjustability in the boom, so it shouldn't be too difficult to get under control.

Also, ccm1495 raises a valid point.

 

[JD]

Inspect the rail where the frames latch. I have seen a problem where the frame starts forming a wear channel causing certain frames (that are used the most) enough slop to drop out of position. This part is replaceable. I remember having a welder build up a braze in the area as a quick fix once.

 

[Max]

I have found that when the fixture is used at the extremes of its zoom it is prone to light leaks.

Do you mean iris, Our comets have no "zoom" only focus

 

[Les]

Comets have two independently moving lenses (front and rear). The front lens serves as the focus lens, while the rear lens acts as the 'zoom lens'. Do your lights not have this?

Good point on the possibility of wear channels, JD. I've seen that on old 1000Q's.

 

[Max]

Sorry to all that chimed in w/ solutions after I said that the self canceling mech eas shot, I just went to take pics for les and it turns out that the self canceling mech is fine. (also thanks for the prompt responses, this place and you all are the best!)
The effect is the most pronounced (therefore photographable) on the blu handle. The red handle does it but not as pronounced. We have R05 in the grn handle so I cannot see the effect even if it is there.
Affixed find Pics of the pool w/ blu gel engaged.
also pics of the boomerang assembly.

 

[Max]

Got 2 lenses in the front after the boomerang, The one directly in front of the boomerang moves on the focus slider, the other one I thought was fixed.

 

[FatherMurphy]

I sold a Comet to a school some years ago, and the box arrived showing signs of taking a hit on the side. The tilt knob was broken, and the latch/cancel mechanism on the boomerang had gotten bent diagonally, so it would hold the colors up, but each color ended up at a different height. If your lights get moved around much, they might have fallen over at some point, and been damaged. Comets are especially prone to doing face plants when being rolled down a hall on their wheeled stand, and they hit a bump - I always try to keep one leg pointed straight ahead to help prevent this.

The MR16 lamp holds the filament and reflector in alignment, but the lamp itself mounts to a plate that is held by three spring-loaded thumbscrews, accessible through the door on the back of the head. If someone's gotten in there and twisted them randomly, that could put the lamp out of alignment with the rest of the optics. Your pictures seem to show an off-center hot spot, is that visible when in plain white light? If you have an even spacing on all three springs (about 3/8" or so), then you should pretty centered and square.

It's also possible that some former student tried fixing something in the past, and didn't reassemble the light correctly. In that case, you might have to spend some time comparing the light in front of you to the exploded parts drawing linked above, or call someone local who knows what a Comet is supposed to look like.

 

[Max]

Okay, I have determined that if I move the zoom lens a little it will fix the problem, now. How do I adjust the zoom lens?

 

[Les]

Okay, I have determined that if I move the zoom lens a little it will fix the problem, now. How do I adjust the zoom lens?

Move the handle circled in red, just like the focus lens.

Or is there some type of internal adjustment that needs to be done?

 

[Max]

Thanks very much

 

[BRDinNC]

The Comet's boomerang isn't terribly unlike the 1000Q boom except this has that self-cancelling feature. The only things I can think of is that the self-cancelling mechanism isn't holding the frame at the proper height; the frame's arm somehow got bent; or that the boom isn't seated in the fixture correctly. There should be a weather striping-like material forming a gasket between the boom plate and the barrel of the fixture. Make sure that's still present. Otherwise, it's hard to tell without seeing a video demo or the entire unit pulled from the fixture. How does the pool on stage look?

You could also cut the gel just slightly too large if you are unable to come up with a fix.

Yes I had to do the same thing to our rental units. It seems to only be an issue at a short throw though.