Conventional Fixtures Altman Shakespeare - hotspot

[randerson]

I'm working on the lighting at a community theater and they have a bunch of 50 degree shakespeare (no S4.... ). I can't get rid of the hot spot on these fixtures to save my life. They have a similar adjustment for this as the S4s but if I turn the knob all the way clockwise (moving the lamp back) there is still a hot spot. And yes the bulbs are fully seated. Any suggestions?

By the way, if you don't know already, these fixtures are horrible compared to S4. Just one short rant about how bad they are... When you turn the little knob that moves the bulb back and forth the location of the hotspot wobbles all over the place, making the larger centering knob useless.

 

[gafftapegreenia]

By chance, do they have the right lamps in them?

 

[JD]

Do any of them work correctly? If so, switch the lamp/cap assy and see if the problem stays with the fixture. You spoke about the hot spot moving around, If it is not in the center, then the lamp or lamp base is off center. That would be the first thing to fix. Once the hot spot is in the center, then as long as the lamp LCL is correct, and the base hasn't been modified, then you should be able to minimize it. Suspect something funky with how the bases are mounted. Do the lamps fit into the base snugly?

 

[derekleffew]

...Do the lamps fit into the base snugly?

One can only assume so, since the base is part of the lamp. What is it that causes people who should know better to misuse the terms base and socket? I think that may be an even greater pet peeve of mine then misusing "than" and "then."

Sorry for the thread derailment, randerson. The idea of exchanging lamp cap s is a good one, provided you have any that are properly aligned. Now it may be such that the optics of the 50° lens train exacerbate the issue. Do you have any non-50° units? Are you using the GLC lamp family, even though EHD, EHG will fit?

If all else fails, R114/R119 can hide a multitude of sins.

 

[randerson]

I do have one fixture that is half way decent, I'll try switching the caps. Yes the "base" fits very snugly into the "socket". In fact, so snugly that you sometimes need tools to remove the lamps. The whole lamp cap also fits snugly into the back of the fixture.

The lamps do look a bit different than what I'm use to working with, I'll get the model number and repost the next time I'm up there.

Yes we have a few 30 degree fixtures, they're a bit better but not much.

I already have R132 on it, which is a quarter of R114

 

[Les]

Seems like an isolated case relating to the batch you're working with, because I've never had terrible hot spot issues with the Shakespeares I've worked with. No, they're not quite as good as Source Fours, but there are much worse fixtures out there. Do make sure the lamp caps are completely seated. They push in, and should click to the right. Then the thumb screw on the back can be tightened. I know you know this, but it's a good thing to mark off the list.

 

[jglodeklights]

It sounds like an HX series lamp may be in use. HX series lamps, with the single, long filament, WILL cause this problem as the reflector is designed for the compact filament. HP600/GLC lamps are my recommendation. GLA's are ok, but somewhat dim. This is the problem when using the standard bi-pin base. Just because it fits in the socket doesn't mean it will work (well). Often, people just don't know better.

End Rant.

I work with Shakespeares all the time, and have no problem with them as long as the lenses are clean and the lamp is correct and isn't old. The centering mechanism does, frankly, suck. The field (at least for luminance) isn't as flat as a S4, except on the 20's, but some R119 should clean it up nicely.

 

[randerson]

The lamps are GLC. So that's not the problem.

The lamp cap is correctly mounted as described by Les.

I switched the lamp caps and it didn't help. When I put the good one back, it was no longer that good. I found that if I just push on the knob or turn it slightly all of the sudden it gets better. (there is also a dimness problem, where the lamps fall completely out of alignment and are considerably dimmer. By messing with the knob the lamp jumps back into the correct position and it brightens up again.)

As far as hotspots, I'm pretty sure that derekleffew was correct that its simply the 50 degree optics. I took a close look at the fixtures from on stage, when your standing just at the outer edge of the beam, you can only see a part of the last lens, the rest is blocked by the tube.

 

[Les]

The field (at least for luminance) isn't as flat as a S4, except on the 20's, but some R119 should clean it up nicely.

Interesting. I said I have never had an issue, but come to think of it, I've only ever worked with 20's.

 

[jglodeklights]

Les, I actually prefer my Shakespeare 20's over a S4 19, especially with patterns. Unfortunately, due in part to the dual lens optics, they just don't have the punch for things like being used as a followspot or medium to deep color washes from my booth pipe (which actually needs a 14 or 15 degree to be the right size anyway).

Been thinking about this, and yes, the Shakespeare 50 is actually spotty in comparison to a S4, but it is still way better than some other instruments. The biggest problem is what you are mentioning. The lamp height and center adjustments just suck. The centering doesn't stay put. The aluminum threaded piece the center adjust screws onto often strips, and makes for a poor paperweight. We try not to strip our box booms at my theater because of this. Simply carrying them the 15 feet to the stage causes them to lose proper bench focus.