Stefano Posted October 25, 2020 Share Posted October 25, 2020 Today my dad and I tried to cook some chestnuts on a "barbecue" (a little more than a pan with charcoal). It was a fail, since the chestnuts were too dry. But it provided material for invisible light imaging. [color=#282828][font=helvetica, arial, sans-serif]Camera: [/font][/color][color=#282828][font=helvetica, arial, sans-serif]Full-spectrum Panasonic DMC-F3[/font][/color] [color=#282828][font=helvetica, arial, sans-serif]Filter: Hoya R72[/font][/color] Lit charcoal glows IR-blue, since its blackbody radiation is heavily weighted towards longer wavelengths, and peaks in the deep SWIR-early MWIR region (roughly around 3 [color=#282828][font=arial, helvetica, sans-serif]µm).[/font][/color] [color=#282828][font=helvetica, arial, sans-serif]F-stop: f/2.8, ISO 200, 1/30 s exposure.[/font][/color] [attachment=20552:P1000206.JPG] [color=#282828][font=helvetica, arial, sans-serif]F-stop: f/2.8, ISO 200, 1/13 s exposure.[/font][/color] [attachment=20553:P1000227.JPG] [color=#282828][font=helvetica, arial, sans-serif]F-stop: f/2.8, ISO 400, 1/15 s exposure.[/font][/color] [attachment=20554:P1000258.JPG] Then I noticed some flames were IR-yellow. That's odd for a flame. We initially used a chemical to help the flame going (not exactly healthy, but it hopefully burned out, even if we didn't eat the chestnuts), and I think it has an emission line in the 700-800 nm range. Sometimes flames change color depending on the chemical burned. I have seen cyan-green flames when burning some thin residues of plastic from a metal wire I heated to cut a plastic bottle. Yeah, avoid this experiments indoor. [color=#282828][font=helvetica, arial, sans-serif]F-stop: f/2.8, ISO 400, 1/400 s exposure (both images).[/font][/color] [attachment=20555:P1000274.JPG] [attachment=20556:P1000275.JPG] Link to comment
colinbm Posted October 26, 2020 Share Posted October 26, 2020 Beautiful study Stafano, I like the violet/blues you have captured. The yellow is interesting, a diffraction grating would have been handy.... Link to comment
Stefano Posted October 26, 2020 Author Share Posted October 26, 2020 Thanks colin. Yes, it would have been interesting to see the spectrum of the flame. If I had a diffraction grating with me I would surely have given it a try. I was once in a supermarket and I was curious whether the ceiling lights were LEDs or HID. I found a diffraction grating in my pocket and took a look. I saw a discontinuous spectrum, which indicated they were HID lamps. Link to comment
Cadmium Posted October 26, 2020 Share Posted October 26, 2020 Stefano, That looks cool! I mean hot!, I mean... Link to comment
dabateman Posted October 26, 2020 Share Posted October 26, 2020 Standing on uts own, I like your last image.Yes you might have been seeing contaminant in the wood or from your lighter fluid. I remember as a kid throwing in powders into the fire to change the visible color.Atomic absorption/atomic emmission is fun chemistry. Link to comment
ulf Posted October 26, 2020 Share Posted October 26, 2020 Standing on its own, I like your last image. So do I.It has a free-floating abstract touch and would work well on a wall in a frame. Link to comment
Stefano Posted October 26, 2020 Author Share Posted October 26, 2020 Channel swapping (BGR) gives this: In this image I also tried to fix the color of overexposed areas (which is not white since there is a white-balance apoplied) by replacing it with white (tolerance 10): Link to comment
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