Vintage Lighting Before the Fresnel, Soft Edge Plano Convex Fixture Found

[ship]

A few months ago, I got in two 8" PC versions of Pevear brand color wheel accessory mounted spotlights for as theorized lighting the cyc. (One is complete from stand to accessory - really cool to find all the parts to it.) Two different styles of the fixtures - one like below where the glass mount is fixed, and one where it's adjustable - really cool! Possibly one of the most unusual fixtures I have ever seen.

Got one of two 6" box spots of the same brand from the down lights on the procenium arch this week. C.1924.... Introducing a theoretical pre-Fresnel... dead branch on the history of lighting tree of pre-Fresnel.

I theorized on the PC fixtures a frosted edge donut lens, here we have this asbestos padded pane of glass holder again (missing....)

Hopefully the second one still in the procenium has its lens - but doubtful in having to remove the lens to change a lamp, and it was still working over a year ago when I got to the theater.

So, PC single lens fixture has a very hard almost photographic grainy edge. Not clean edge like a modern Leko.... just kind of hard edge but hard to describe in once designing a show about that look from the PC. Got an "Elephant in a Shoe Box" award in part of this tasked lighting concept for that show. I have designed with PC fixtures in the past.

Kind of brilliant if my theory holds of a frosted donut edged lens softening the harsh edge of a PC fixture. Nobody else was doing this seemingly except Pevear. This would in theory make a kind of Fresnel soft edge beame look out of the otherwise PC beam of light. This is also in 1924, the Fresnel was not invented until 1928 or 1932 subject for debate in various texts. Love my job in at times in finding stuff. Unfortunately I don't always get a sample of what I see, but at least I saw it and know it exists.

Curious on top of the fixture is some kind of bracket / holder for a something I don't know... Assuming it's a down light projecting thru holes in the ceiling, what is the point of this bracket for something at the top of the fixture? Way too many vent holes - inefficient in labor needed to light shield the amount of holes, means it's a fixture for more than one angle. Never seen a card holder bracket to a fixture before. No idea on what is up with that other than, if lens is pointed downward as normal, any such card would tend to fall out. Curious.

 

[tjrobb]

Neat! Somewhere on here I shared the PCs I found from our 1928 theatre. Have a mogul screw base lamp and no frills. Fun to see how technology changes.

 

[ship]

The first I restored quick without learning from it. This second one for the museum, I really took apart. Pound rivet conscruction where not bolted. No spot welds. Looks kind of like Kligl designs in larger box spots with large holes everywhere. Perhaps Kliegl in a 6" lens also had the HRG glass frosted donut.

Again as per the PC version in a different post... these lights have a bracket to hold a 1/8" thick sheet of glass before the lens. In both of these box spot fixtures, and one of the PC fixtures, the lens is at a fixed distance to the lamp, and both move on the same normal PC or Fresnel focus assembly. The reflector on all is fixed to the rear of the housing in being different than a Fresnel, or a PC with the reflector as an option - but on the same focus carriage.

So internally, it/they work more like a beam projector of scene machine in lamp focusing seperate from the reflector. On all is the 1/8" thick heat glass mounting - on one PC fixture it is seperately adjustable, but on the other three at a fixed diistance. In none of the two normal shaped PC fixtures with a color wheel for Cyc light use, or the other two 6" box spots did I see almost 100 years later any HRG lenses between lens and lamp. Yet in all there was some asbestos padded pane of glass there.

Theory on my part is that is is a high temperature glass frosted donut, so as to soften the PC edges of it's single lens. And because it was just a pane of glass, it easily broke during the years.... the Fresnel design worked better and was cheaper to make by 1934, or was it 1928.

This fixture had a lot of rust. I want to save it's patina so am only using Rusoleum Rust inhibitor on it. Have to wipe the oil off over a period of days. Just noted that the top of the fixture I thought was a message pad is actually an access port for changing the lamp. Never seen that before. Probably why both the 6" box spots' lens locking in gel frame mounts were broken off also. Nobody after generations of use realized it was there.

 

[ship]

So something I have never seen before, and removed from this fixture... failure was gas seal at the base of the lamp. I do not know wehere the bubble was - top or bottom towards or away from the lens verses reflector. But there is a bubble in the globe of a 400wG30/SP lamp. Filament in tact, but as I unscrewed the lamp, that was failed in attachment. In this fixture, the proposed frosted donut glass plate was long gone by at least 50 years as a guess. No fragments of donut glass plate in evidence inside the fixture - cleaned out and completely gone.


A 400G30/sp is soft limeglass and not quartz does not have problems in touching it. The filament didn't explode or burn thru the globe. Facinating at least for me in yes, the baseseal failed, but should not causethis - should be a blackened globe ifanything. Perhaps a very dirty lens and gravity?