Recent content by dbn

I downloaded the Light Jockey User Manual, and after a breif scan, I'm left with the question as to whether it natively supports "desk channels", i.e. dimmers for non-moving lights. Anyone familiar enough with this product to answer that question off hand? Or do I need to go back and carefully...

Might have been, but I always thought it was the fresnel lens that was developed for lighthouses. I've seen some 18th century examples (in museums).

Step lenses are different from fresnel lenses. Both are "reduced glass" equivalents of plano-convex lenses. In a stepped lens, the front surface is a smooth convex, and the back surface is a series of flat, concentric "tiers", with the deepest "cut" at the center. Think of the shape of a...

I'm guessing, too, but it looks like Van may be right. These look like they may be lenses that were intended to mount inside the barrel of an instrument via a narrow slot and slide back and forth for variable focus or zoom. The rubber layers and the tightening wing-nut look like they would...

This is slightly off-topic, because it isn't a pointer to down-loadable CAD symbols, but it's an interesting reference. The USITT is in the process of standardizing CAD symbols for lighting design. The latest draft, still available for public viewing on their web site is at...

There are still some of these in use. :-) I think there is a Channel / Submaster switch on the rear apron, to allow the Scene X channel faders to become submasters. To record the submaster, you push and hold the green illuminated button, run the submaster up to 100 and back to 0 then push...

Not advised, to be sure. It's not so uncommon a practice in the industry, though. We purchased all of our 360Qs used from two rental houses (as they were coverting over to S4s). All of them that came from one large rental house were lamped with FEL. Those from another shop were lamped with...

There are some surprisingly broad and apparently obvious patents being granted these days. I've dealt with this enough to know that you have to actually examine the claims in each patent to see what it really covers, however. To perform patent searches in the US, you can use this link...

Having 240 volt mains is an advantage in terms of the decreased ampacity requirement of conductors and connectors. It is a disadvantage in terms of the increased fragility of indandescant lamp filaments, however.

Sorry, that's not correct. With transformer windings, as with all inductors, the inductive reactance must be considered in addition to any DC resistance. The back-EMF reflected from a lightly loaded transformer secondary to the primary winding will increase the inductive reactance of the...

The utilities don't like it when you draw unbalanced power from their system. Yes, it does tend to average out. The system design is for balanced consumption, though. Additionally, _some_ systems used to have what's called a "reduced neutral". Given that evenly distributed loads on a three...

I've rented these on a number of ocasions, and the rental units always come with a Cam-Lok tail. I think that from the factory, they come without a tail or connector, just an internal terminal block. The CD-80 portable packs can be internally strapped for 120/240V single-phase (2-pole) or...

Ah, now I understand. We only have GLC/GLA lamps in the FOH (Box Boom) positions, which in the repertory plot are gel'ed with light warms (LUX 02, 05) and medium blues (LUX 65, 68). These tend to be used at full or near full most time for most of the shows in our venue. We have Altman 65Q...

How quick is "quick"? Remember that gels are "expendables" and not expected to last a very long time. The lower the transmissivity, the shorter the life. If the R/G/B set-up is sufficiently long term so as to justify the investment, you can switch to dichroic glass color filters. These are a...

My favoriate on the artistic issues of design is another out of print book: "The Lighting Art: The Aesthetics of Stage Lighting Design" by Richard H. Palmer, (C) 1985, ISBN 0-13-536566-X.