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UltravioletPhotography

MultiSpectal reflectance test of fat, sugar, plastic, flowers


dabateman

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Thinking about absorption of and the fuzzy limit of looking through stuff. I am becoming interested in what allows for the reflection of light we see. So I set up a first attempt test with stuff to try and represent "pure" forms of salt, fat, protein, plastic and other. However, I know what I have here is not ideal. Also couldn't think of a best pure protein source. Maybe a chunk of Marmite may work (yeast extract), I actually have a jar.

 

I have a 15W long tube 302nm bulb above the stuff and one immediately in front, shinning slightly upwards. These are about as close as I can get to the stuff. They also allow for a nice range of UV and into IR, that nearly matches the cameras response as Johnathan has shown.

 

The lens is Pentax UAT at F8 for all images on my full spectrum EM1

 

Visible labeled image:

post-188-0-25048500-1560585050.jpg

 

1000nm 2mm filter ISO 400, 4 seconds:

post-188-0-76317300-1560583882.jpg

 

720nm fitler ISO 200, 1.3 seconds:

post-188-0-26720500-1560583896.jpg

 

No filter (unlabeled), ISO 200, 1/20 seconds:

post-188-0-45710900-1560584352.jpg

 

330WB80 improved filter, UVA at ISO 200, 2 seconds:

post-188-0-93769500-1560583923.jpg

 

313bp25 with 330WB80 (to cut any IR), ISO 200, 15 seconds:

post-188-0-03970800-1560583939.jpg

 

300bp10 with 330WB80 (to cut any IR), ISO 800, 30 seconds:

post-188-0-22676400-1560583952.jpg

 

280bp10 with 330WB80 (to cut any IR), Auto color adjust in IrfanViewer, ISO 800, 60 seconds:

post-188-0-91482300-1560583972.jpg

 

280bp10 with 330WB80 (to cut any IR), Auto color adjust in IrfanViewer, ISO 800, 1118.4 seconds:

post-188-0-51794700-1560583992.jpg

 

 

Not surprisingly PTFE is the best at reflecting the light through all wavelengths. Plastic wrap was also good, as was plastic metal looking like foil. The Coca butter (pure fat) also was reflective down at 280nm, as was the salt and rock. The other stuff is hard to see. But I don't think the sugar is very reflective in UV and may be what causes the darkness we see in flowers. I will have to test with a white sugar cube one day.

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  • 2 weeks later...

This was a cool setup with all those items. Love the inclusion of a chocolate chip.

 

It's quite impressive that you are getting results down in the germicidal range. (You didn't mention eye/skin protection but presumably you did use some, yes??) For what it's worth, your 280BP10 photo looks pretty much like what I got with my 293BP10 in sunlight. Faint reflections and lots of noise. I suppose if we had 10 or so of those 302 tubes, then maybe something more would be recorded. But I'll leave that to you or others. Me, I'm chicken about playing with germicidal rays!

 

On a side note, there must be somewhere some UV reflection (or UV absorption) charts or data for such substances as sugar, cocoa butter, salt, etc.

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Being easily accessible and allowing me to see something at 280nm, I would say the 302nm bulbs are extremely dangerous and should be avoided.

 

The 100% chocolate chip was fun and I do see reflectance from it. Would be interesting to maybe test a bunch of different % chips to see the sugsr effect.

 

I have been so busy with other stuff, I haven't followed up on the sugar test yet either.

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