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UltravioletPhotography

Laser-Stimulated Fluorescence of a Pumpkin


Andy Perrin

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Here is a pumpkin (or in some parts of the world, a squash) using Laser-Stimulated Fluorescence (LSF). LSF was described in my first post on it back here. Please reference that post for the procedure and background, safety requirements, and equipment used.

 

Camera was the Sony A7S (modified).

Lens was the Nikkor 20mm/3.5 (which I haven't tested in UV reflectance).

Filters on camera were the Tiffen Haze 2E + BG38 2mm.

 

30 sec, F/16 (for depth of field reasons), ISO400.

White balance altered to suit taste.

post-94-0-25653400-1610861073.jpg

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That seems to be working well Andy.

I wonder if you had two lights working in parallel, either side of the lens, you would get less shadows.

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Thanks Steve!

 

Colin, my big problem right now (aside from figuring out how to attach one of those Powell lenses which is turning out to be very hard) is that the light painting is hard to do without leaving bright lines by lingering too long in one spot. I badly need to automate the scanning process with a turntable setup. Dealing with two lasers at once is a problem for some other day!

 

In this case I actually like the shadows though.

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dabateman actually it really is leftover from Halloween. It never rotted so I never threw it out.

 

Stefano I actually shot a UVIVF also but it’s very similar. Colors are slightly bluer. The intensity isn’t making much difference to the results here because the pumpkin already glows pretty strongly in UV.

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There is a beautiful unexplored jurassic-jungle-world in there. Dinosaurs might be encountered.

 

An interesting aspect photographically is the cool reflection (perhaps off aluminum foil?) underneath

which gives the impression that the pumpkin is glowing from inside.

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Andy, you have a good compositional eye in case I haven't mentioned that before.

 

For about a year I have been quite lazy about making any UVI fluorescence photos. They can be so cool and dramatic and interesting.

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I really like these images and their composition.

 

I wish I too had time and locations suitable trying UVI fluorescence photos.

 

Andy, what is the reason for using a laser instead of a high power LED with 405nm?

The line laser idea makes my design mind literally spin with ideas of how to get some scanning of the line over the motif.

I am tempted to get a line laser and do some proof of concept tests of my ideas.

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Ulf these are proof of concept tests for large scale fluorescence on the sides of buildings! I want to do fluorescence at the 10m scale.

 

I’m actually already working on a turntable idea with a stepper motor.

 

Also- line lasers with cylinder lenses are a bad choice for this actually. Powell lenses are a must.

Check the paper I linked on the original topic here:

https://www.ultravioletphotography.com/content/index.php/topic/4293-laser-stimulated-fluorescence-first-tests/

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