Another ebay oddity.

[gafftapegreenia]

I'm thinking the composite that holds the envelope to the screw base would loosen and detach.

I'm going to attempt a summary:

Mazda was GE's name for a standardized lamp system. These lamps used the then-new tungsten filament technology. This was an improvement from the old carbonized filaments. GE then liscensed the use of the Mazda name to other manufacturers, such as Westinghouse, to denote to the consumer that the lamps bearing such a marking were quality, standardized lamps.

As for reflectors, I have a few theories.

The first is that most reflectors were silvered glass. This would probably have been too expensive for the standard spotlight. Seeing as most manufacturers saw a fixture with a lense as a great improvement over say, a box flood, they might have seen no need for the "extra" reflector.

Also, in the early days most P/C fixtures with incandescent bulbs were refitted arc spots. I don't think many arc spots used reflectors, if any did at all. I believe that all the knobs and levers for arc control meant a reflector got in the way.

 

[avkid]

I'm thinking the composite that holds the envelope to the screw base would loosen and detach.

Wow, sometimes I completely forgot the most obvious things.

 

[ship]

Yep, that’s what I’m thinking especially if it were a hot washing. Rise and hold perhaps if adjustable for cold water setting. Still Alcohol and or if necessary glass cleaner (incandescent lamps only) on the rag and not sprayed on the glass, than followed up with denatured alcohol would probably be the only safe solution.

Thanks for the summery.

Box floods assuming like an ovalite does send a directional beam instead of a soft wash. Still there are effects projectors and versions of follow spots within that era that had reflectors. Money as with today can be a factor but polished aluminum will have been an option. In these types of fixtures, at some point the stage and studio Fresnel came on the market and it had reflectors. PC fixtures by way of being the same fixture for all intensive purposes / different lens also started at that point using the same reflector. I’m thinking nope, that is not the answer why these fixtures did not have a reflector as a primary reason beyond budget and slapping oneself upside the head and thinking “I could have had a V-8.”

Think the screw base lamp, how is it different than a medium pre-focus lamp? On the Major PC fixture, it for a lamp focus slide has a three part system to it. The slide part is 3/8" NPT. In it sleeves a 1/4" NPT fitting that at it’s center is tapped for 10-32. The #10 screw locks that fitting to the lamp base yoke - a little brass yoke inside the two piece aluminum lamp base mount and surround. The 1/4" NPT fitting has a slotted side to it which lets you screw the lamp base assembly up and or down, while the 3/8" NPT part allows you to focus the light forward or backwards in relation to the lens.

Why was it necessary to focus the lamp up and down in the early days, as opposed to on a Fresnel or even more modern screw based PC fixture, there is no such adjustment. Granted it could be in part for a more oval beam but there is only realistically about ½" of play up or down.

Given this concept and past notorous lamps that were never really the same in needing to bench focus each time, plus the screw base that could be screwed in more or less dependant upon who is doing it, and the screw base lamp’s filament that could wind up in any clock wise setting, I’m thinking that doing a reflector will have made the fixture too inefficient in stray hard edge beams everywhere. Instead, while they lost at least 50% of the light output, some extent of point source to the light was maintained. A parabolic reflector will given the range of not able to focus a screw base lamp, perhaps it was not feasible to do a reflector. It’s a concept.

Also in the “Go Fres” USITT tech briefs, removing the reflector or covering it is the concept as with doing linenbacher projectors. Point source of light perhaps trumped the efficiencies of reflectors.

 

[gafftapegreenia]

Well, ship, I have to say, right when you started talking about screw bases vs. pre-focus I had one of those "duh" moments. That sounds like a very likely reason as to why few fixtures had reflectors.

Refresh my memory, what is a go-fres exactly and how is it used? Is it really just a Fresnel without a reflector?

 

[ship]

Yep, USITT Theater Technology Exhibit 1991, article 15 by Mark Zetterberg, Central Washington University.

Remove the lens and cover or remove the reflector. Both as shaft of light in the Craig sense and Linnenbach Projector sense, a Fresnel can be used. The sperical reflector creates multiple images in the projection field. Though as mentioned, multiple images can at times be useful.

In this write up, they found products such as Gam Wrap - foil wrap adiquate for use as a gobo when placed right side up in the accessories slot of the fixture. Steel cut gobos/slides would be better but it depends upon heat. Glass slides could also theoretically work.

This study also noted putting this slide into the gel holder of a rotating barn door so as to further cool the slide, adjust it in rotation and increase the distance from the lamp to sharpen it further. This and also fight spill or direct the beam further plus focus it further. It appears from the article that quite the control was made in this technique by way of just 6" Fresnels.

A few years back after reading this article I did try this concept only I was using two 2Kw Century 8x9 fixtures. Removed the reflector and entire gate/shutter assembly, than mounted a like 24" square slide assembly to the fixture something like 24" from the lamp. While not all the way refined by way of plexiglass and black paint, it did amazingly a absolute magical job of projecting scenery on my backdrop. We are talking a 20' long section of backdrop covered by a single fixture placed 4' from that drop on the side of it. This projected scenery from behind a scrim to wash and even it out a bit. Yep, technique works.

By way of Fuchs, you see box spots that have PC, Fresnel and no lens as used. For a Fresnel, all three options are a feasible way to use it by way of expanding your inventory. Remembering that the modern lamps are a bit more accurate, it might not always be necessary to remove the reflector as further note.

 

[gafftapegreenia]

Very Interesting. I'll have to try that out some time.

Back to the reflector question. I remembering reading in one of the old Kliegl cataloges about a P/C spot that was advertised as also being a flood- simply remove the lense plate.