What was the purpose of the painting of the step lenses, perhaps it's the same purpose on Fresnel lenses?
Fresnel Lens types
- Thread startership
- Start date
What was the purpose of the painting of the step lenses, perhaps it's the same purpose on Fresnel lenses?
Ship,
The answer to the question about painted steps is in my privious post.
I think W. Bellman in talking about cheap and expensive was refering to cheap cast lenses and exspensive ground lenses. Curiously enough most of us just use the things with no discoarse from the manufactures about the optical setup. Can't say I have ever seen any info on optics from a manufacturer. I do know they keep getting better, or at least the ones I use.
You have never done a nautical play that needed a lighthouse????? ;-)
The answer to the question about painted steps is in my privious post.
I think W. Bellman in talking about cheap and expensive was refering to cheap cast lenses and exspensive ground lenses. Curiously enough most of us just use the things with no discoarse from the manufactures about the optical setup. Can't say I have ever seen any info on optics from a manufacturer. I do know they keep getting better, or at least the ones I use.
You have never done a nautical play that needed a lighthouse????? ;-)
Last edited:
Okay, research can be handy. Willard Bellman, Lighting the Stage Art and
Pratice second edition 1974(ISBN 0-8102-0040-6) pages 79-81
Discussion on Fresnel lenses "black enamel is used on oval beam cylindrical lense...these do not have the dappling pattern on the back and thereby produce a sharper edge beam" The oval beam is a pattern on the back of a Fresnel lens.
This oval pattern apparently provides slightly better optical properties, as I read the book there may be a lot more of this around then we might think.
Again, if I understand the priciple correctly the black enamel on the risers cuts down on stray light to help keep a sharper edge.
As I only currently use one instument with a concave lens I have noted all I can on that.
Pratice second edition 1974(ISBN 0-8102-0040-6) pages 79-81
Discussion on Fresnel lenses "black enamel is used on oval beam cylindrical lense...these do not have the dappling pattern on the back and thereby produce a sharper edge beam" The oval beam is a pattern on the back of a Fresnel lens.
This oval pattern apparently provides slightly better optical properties, as I read the book there may be a lot more of this around then we might think.
Again, if I understand the priciple correctly the black enamel on the risers cuts down on stray light to help keep a sharper edge.
As I only currently use one instument with a concave lens I have noted all I can on that.
Last edited:
From the Kliegl.com website.
Turns out Kliegl had the patent for the oval beam lens.
www.klieglbros.com/patents/2853599/us002853599-002.pdf[/[/URL]URL]
Turns out Kliegl had the patent for the oval beam lens.
www.klieglbros.com/patents/2853599/us002853599-002.pdf[/[/URL]URL]
Last edited:
Ok time to take a whack at it, first, the non-fresnel varieties, to clear things up.
1)Plano-Convex with clear plano side. Direct lighting with hard edge.
2)Plano-Convex with stippled back. Lighting harder than Frensel but softer than a Leko.
3)Step Lens without risers. Spill light resulted from the cutaway sections, gave rise to the...
4)Step Lens with risers. Baked black risers to eliminate spill light. Was developed for use in Lekos.
Ok Fresnel time.
1)"Standard" Fresnel. Cutaway portions on face with a plano back. Stippled to diffuse ring patterns, such as seen on Step Lens. Softest beam. I have also seen what amount to small plano-convex 'bubbles' or a hexagonal pattern instead of the stippling. There is also another version that has crosshatching for a wider spread, don't know if that saw stage use though. By my book a frost is a transluscent coating where as stippling is a textured "sand like" pattern molded in.
2)Oval Fresnel. Has striping on the plano side to spread the light beam.
3)Concave Fresnel. I actually saw this in the KOPP catologe. Has the fresnel cuts on the face and a concave back, not plano. I would assume it has a wide light spread.
Guess time, could the fourth be:
Square Fresnels? The earliest Kliegl cateloge's to have Fresnels had them in square versions. I'd love to see one of those first hand, but then again I might already have, the old lights in the ceiling above the bleachers in the gym at school look like square Fresnels.
Reverse Fresnels? Flat convex side with fresnel cuts on the concave side? The KOPP has a description of a "6" DIA. X 7-3/4" FOCUS CONVEX FRESNEL STEP LENS - 4 RISERS" Really I think this is just a version of the step lense with angled risers, similar to the very wide spread lenses used on those round semi-truck taillights
But what I think the fourth is is a Fresnel lense with black risers. I just found mention of one in a Kliegl architectural cateloge. Is is advertised as having low "ceiling spill". Essentially, its a built in tophat.
I could probably sit here all night classifying every lens variation shown in the KOPP cateloge.
And since I took the time to look through the KOPP cateloge, might as well mention the basic convex glass roundels:
1)Plain smooth.
2)Stippled roundel.
3)50 degree spread fluted roundel.
4)Cross hatched roundel
and one other I've come across
5)Plain roundel with small glass beads, such as used in highway lines, coated on the concave side. Found them on some old Major striplights.
Sometimes I think I obsess over variations.
KlieglBros.com is a great way to learn some history, if only there were similar sources for Major, Capitol and Century. I never find these old fixtures online and have NEVER seen catologes for them. The KOPP cateloge is useful too, I didn't even think they still existed till I found them a few months ago.
Altman also has a "What's Old" page, good archive of old products. Its crazy how long the 360/360Q line has been made.The Source 4 is also 15 years old this year.
1)Plano-Convex with clear plano side. Direct lighting with hard edge.
2)Plano-Convex with stippled back. Lighting harder than Frensel but softer than a Leko.
3)Step Lens without risers. Spill light resulted from the cutaway sections, gave rise to the...
4)Step Lens with risers. Baked black risers to eliminate spill light. Was developed for use in Lekos.
Ok Fresnel time.
1)"Standard" Fresnel. Cutaway portions on face with a plano back. Stippled to diffuse ring patterns, such as seen on Step Lens. Softest beam. I have also seen what amount to small plano-convex 'bubbles' or a hexagonal pattern instead of the stippling. There is also another version that has crosshatching for a wider spread, don't know if that saw stage use though. By my book a frost is a transluscent coating where as stippling is a textured "sand like" pattern molded in.
2)Oval Fresnel. Has striping on the plano side to spread the light beam.
3)Concave Fresnel. I actually saw this in the KOPP catologe. Has the fresnel cuts on the face and a concave back, not plano. I would assume it has a wide light spread.
Guess time, could the fourth be:
Square Fresnels? The earliest Kliegl cateloge's to have Fresnels had them in square versions. I'd love to see one of those first hand, but then again I might already have, the old lights in the ceiling above the bleachers in the gym at school look like square Fresnels.
Reverse Fresnels? Flat convex side with fresnel cuts on the concave side? The KOPP has a description of a "6" DIA. X 7-3/4" FOCUS CONVEX FRESNEL STEP LENS - 4 RISERS" Really I think this is just a version of the step lense with angled risers, similar to the very wide spread lenses used on those round semi-truck taillights
But what I think the fourth is is a Fresnel lense with black risers. I just found mention of one in a Kliegl architectural cateloge. Is is advertised as having low "ceiling spill". Essentially, its a built in tophat.
I could probably sit here all night classifying every lens variation shown in the KOPP cateloge.
And since I took the time to look through the KOPP cateloge, might as well mention the basic convex glass roundels:
1)Plain smooth.
2)Stippled roundel.
3)50 degree spread fluted roundel.
4)Cross hatched roundel
and one other I've come across
5)Plain roundel with small glass beads, such as used in highway lines, coated on the concave side. Found them on some old Major striplights.
Sometimes I think I obsess over variations.
KlieglBros.com is a great way to learn some history, if only there were similar sources for Major, Capitol and Century. I never find these old fixtures online and have NEVER seen catologes for them. The KOPP cateloge is useful too, I didn't even think they still existed till I found them a few months ago. Altman also has a "What's Old" page, good archive of old products. Its crazy how long the 360/360Q line has been made.The Source 4 is also 15 years old this year.
Similar threads
