When it comes to seeing in strange spectrums, David Prutchi is the guy you want to talk to. He’s taken pictures of rocks under long, medium and short UV light, he’s added thermal imaging to consumer cameras, and he’s made cameras see polarization. There’s a lot more to the world than what the rods and cones on your retina can see, and David is one of the best at revealing it. For this year’s talk at the Hackaday Superconference, David is talking about DIY Ultraviolet Photography. It’s how bees see, and it’s the bees knees.
The visible portion of light is just a tiny portion of the spectrum; right now, there are kilometers-long radio waves flying around you, and hopefully not too many gamma rays blasting through your skull. Closer to the visible portion of the electromagnetic spectrum, we have infrared and ultraviolet. Infrared visualization is well-studied, and even moreso since the Raspberry Pi foundation started shipping a camera without an IR filter. Ultraviolet, on the other hand, is a bit stranger. That doesn’t mean it’s not used in nature; bees can see deep into the ultraviolet, and flowers have evolved to be visible to bees.
But this is a talk about UV photography, and this means modifying a camera. This means taking apart a camera and removing the IR and UV filter. Yes, all cameras are very sensitive to IR and UV, and most cameras have a filter that only passes the visible spectrum of light. Of course, once you get rid of that IR and UV filter, you’ll need to block out the IR and visible light. This can be done by simply stacking UV band-pass filters and IR short-pass filters. Dedicated UV lenses are extremely expensive, but photo enlarger lenses are nearly transparent to UV, and some old Soviet and East German prime lenses don’t have a UV-blocking coating.
This is an amazing talk that goes into the depths of UV photography, in the end producing UV images simply from stacking filters, no Photoshop involved. Of course, this is just a teaser; David literally wrote the book on UV imaging with a DSLR, and a quick perusal of this volume shows there’s much more than a thirty minute talk can cover.
Update: David Prutchi has made the slides for this talk available as a PDF.