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UltravioletPhotography

Lee #729, #183, C47 Dichroic compared


Cadmium

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This is the Lee #729, #183, and MR16 C47 Turquoise 7 Dichroic compared.

The Lee Scuba Blue #729 is the original filter I used for this.

The Lee #183 Moonlight Blue is one that David tried.

The Lee C47 is a Dichroic glass filter similar in transmission to #729.

 

Summary:

Each of these three Lee filters were stacked with Schott KG3 2mm.

Each of these is individually white balanced on a gray card, in camera, no post processing, no mixing of white balance between filters.

 

In my opinion, the #729 stack is still the reddest. It is redder than the #183, or the Dichroic glass C47 filters.

I will show the #729 last, along with one of my original #729 shots from March.

 

Lee #183

post-87-0-20410200-1557448669.jpg

 

Lee Dichroic glass C47

post-87-0-61928300-1557448713.jpg

 

Lee #729

post-87-0-10011400-1557448769.jpg

 

Lee #729 With a slightly different time of day, light angle, etc. (March 17, 2019)

post-87-0-29679700-1557448854.jpg

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Well one thing is for sure that for some reason with the #183 you loose your truck. Must have been really expensive.

 

I am still looking for an out of the camera more golden lee combo. That is why I like the #183 more than the red #729. But have not had any good sun light, so testing will wait. Also ideal if it can be used directly on my EM5mk2, which is not full spectrum converted. But that might be a long shot. The IR filter is weak on Olympus cameras, but maybe not weak enough.

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Well, if you like #183, then their Dichroic C74 performs the same, and it is glass, and not too expensive, comes 3mm thick standard, could special order thinner though.

That is not my truck.

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I hadn't heard of Lee dichroic filters before. What's more interesting is this statement on their website:

 

“After experimenting with standard polyester gels, it became apparent to us that longevity was a significant issue with LED sources.

The bleaching of the dyes in the gels did not allow for permanent installation, which is a necessity in large scale architectural applications.

The dichroic coatings allowed us to access a range of architectural filters without worrying about fading, and the polycarbonate base material gave us the flexibility to customize bulbs in ways not possible with glass.”

 

In the years I used filters infront of very hot hallogen and incandescent light bulbs, I saw melting, but not bleaching. I wonder what makes LED lighting different. This was in my past life doing lighting and sound work for high school plays.

 

Now I use a holder infront of my Sd15 internal dust blocking filters on Leds. So hopefully the dichroic uv/ir SD15 blocking filter will prevent the bleaching. I do notice that the SD15 filter gets quite hot though, so maybe a heat distribution issue. I may have to rig up a tube to allow for better cooling.

 

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Andy Perrin
In the years I used filters infront of very hot hallogen and incandescent light bulbs, I saw melting, but not bleaching. I wonder what makes LED lighting different. This was in my past life doing lighting and sound work for high school plays.

I'm speculating, of course, but halogen and incandescents have very little UV and a lot of green/red/IR. LEDs may have a lot more blue in them. Blue and UV light would be more likely to cause photobleaching, which requires high energy photons to drive the reaction.

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I am not using them here for lights, I am using them on the front of a lens, and thus not exposed to long intense radiation,

and given the price of the polyester filters, I have no worries.

Architectural lighting is a whole other scenario.

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It is hard for me to decide which of the Lee #729 and MR16 C47 I like best. There is some subtle difference, which I can't really define.

They are very close though.

The polyester costs about $7, for a rather large sheet, and the C47 costs about $15 plus shipping, and you can only get the C47 from Lee 'project department', it is special order, but doesn't take more than a week or two,

looks like just clear glass with dichroic coating on one side.

You can special x special order them in thinner glass, but I don't know what the price would be on those, or the quantity.

The one I got was 50mm dia x 3mm thick.

The quality...? I mean the diachroic surface has a few scratches right through the coating (yep), maybe they sent me a kind bad one? ...but it works.

If I were getting a quantity of them, then I would complain about dichroic surface scratches. But then, maybe they don't think about that the way I tend to... giving they expect them to be used for lighting, I don't suppose they expect them to be used on a camera lens. I get a little picky about filter surface quality, even if it doesn't show up in photos. It represents quality though, one way or the other.

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The C47 alone is almost the look I am looking for, just a little dull. I will have to play with some of my current filters using incamera WB now. I have a feeling based on this dichroic spectra, that the dichroic luminol filter I have, that has been poorly damaged (coatings wipped off), may actually work for what I wanted. Will have to test.

 

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