Conventional Fixtures - Lycian Midget with GLD?

[BobHealey]

Has anyone tried switching their 1206 Midgets from FEL to GLD? What were your thoughts with the results?

I'm in the process of getting all the FELs out of the 360Q collection, and needed to put fresh lamps in the spots for an upcoming show. I'm not happy with the bench focus I was able to achieve with the GLD. The beam does pick the actors out of the 6x16 FEL wash though, so the GLD is working. I just haven't been able to eliminate the filament shaped hotspot.

I'd really prefer to not have any G9.5 lamps greater than 750W on hand due to the fun I'm having fixing the 6x16s and 6x22s with cooked innards.

[JD]

Check the spec on the LCL or "Light center length" between the two lamps, if they are the same, it is worth a try. The FEL is a sloppy lamp for follow spots although several use it (Altman 1000Q among others.) The reason I say it is sloppy is due to the length of the filament. For a follow spot, you want as close to a point source as possible. To use the FEL, spot manufacturers end up wasting a lot of the lamp output, which is why the Altman Luminator at 360 watts is almost as bright as the 1000Q. I remember the filament being shorter on the GLD, but it has to have the same LCL to be effective, and the reflector design may still work against it as it was designed for an FEL.

[derekleffew]

LCL of 120V 1000W 300hr 27,500 lumen FEL: 2.374 in (60.3 mm)
LCL of 115V 750W 300hr 19,000 lumen GLD: 2.370 in (60.2 mm)
So close enough.


The difference may be in the geometry of the ellipsoidal reflector, specifically the flatting might have been "tuned" to the longer filament of the FEL. It's possible that the fixture doesn't allow enough peak-cosine adjustment (axial socket travel in-out). Then again, if you're getting an exact image of the filament being projected in the beam, the reflector is doing its job perfectly. Too perfectly, in fact. I've seen this in PC spots with a non-coated/textured lens. Only way to eliminate the filament image is to defocus the beam. Some moving lights (x.Spot) have a "beam flattener" or "beam homogenizer" after the lamp and before the lenses to compensate, but it adds a loss of intensity.


Personally, I'd go the other direction, and use Ushio's "1200W FEL" in the followspot: BulbConnection.com - $26.19 Ushio 1000972 JCV120V-1200WCH Replacement Lamp . But I always want the brightest, loudest, biggest ... Must be a Vegas thang.

[BobHealey]

I was just trying to get FELs out of the theater so they wouldn't keep ending up in 360Qs where they don't belong, and then run at 40% because they're too bright otherwise.