colinbm Posted October 15, 2014 Share Posted October 15, 2014 I have just come across this, dated 4th August 2014, New UV lamps for Ultraviolet photography.http://chsopensource...uv-lamp-tested/CheersCol Link to comment
nfoto Posted October 15, 2014 Share Posted October 15, 2014 A pity it is just a strong 365 nm illuminating device. Wish it were broadband UV. Link to comment
Andrea B. Posted October 15, 2014 Share Posted October 15, 2014 Col, that's a nice find.If one is going to use a UV-LED type of lamp, the ones mentioned in this review look very nice. And that is a good review, as reviews go. Covers the pros & cons, etc. For photography, we know that a UV-LED (365nm) is somewhat narrowband and will give a somewhat monotone result as far as false colours go. However, it will certainly help record a UV signature. (I'm writing that for those new to UV photography.) Like Bjørn I wish that multiple UV-LEDs could somehow be combined to give a broadband UV lamp. Maybe we will get that eventually. Another cool point => I'm very pleased to have been pointed to that site where I can read a bit more about the use of UV/IR in the Art world. I see there a section on Infrared fluorescence and other interesting stuff. Chlorophyll emits infrared fluorescence? I MUST try to induce that. Link to comment
Andrea B. Posted October 15, 2014 Share Posted October 15, 2014 OK, the guy used a max-max CC1 filter to block IR. I wonder if it blocks enough IR to be able to claim Visible-induced IR Fluor in chorophyll ?? Looks to me like there is enough IR between 700-800 with that CC1 to have produced just an IR photo in a long 30" exposure. And what about the UV component of the CC1? Maybe that IR fluor (if it is IR fluor) is really UV-induced? Again, it was a 30 second exposure. This could have "forced" that IR leak. But I won't know until I try this myself. IR Fluor in Chlorophyll Photo here: http://chsopensource.org/2013/04/29/infrared-fluorescence-photography-review-2/#comment-118454 Some references are given. I will go look them up. Link to comment
Andrea B. Posted October 15, 2014 Share Posted October 15, 2014 Chlorophyll a fluoresces around 673nm and 735nm. See: http://en.wikipedia....iki/Chlorophylland also http://en.wikipedia....ll_fluorescence They show a Chlorophyll Fluorometer - how cool is that !!See: http://en.wikipedia....ted_fluorometer Turns out that measuring chlorophyll fluorescence helps determine plant "stress".The more fluor around 735nm, then the more chlorophyll content and thus the healthier the plant. ***** Anyway -- I don't think the guy on the art site showed IR fluorescence if he was using a Heliopan 1000 filter !!! Should we tell him? ***** Shootpoop. All those articles and I can't yet find what wavelength induces the chlorophyll fluor. ***** I LOVE my website. I learn SO MUCH interesting stuff from everyone and from what's posted here. Thanks again Col for this morning's interesting chain of links. :D Link to comment
Andrea B. Posted October 15, 2014 Share Posted October 15, 2014 Chlorophyll fluorescence - a practical guide by Maxwell & Johnsonhttp://jxb.oxfordjou...9.full.pdf+htmlBut dang it. It also does not mention inducing wavelengths. Chloro fluor is very small => 1-2% of total absorption.There is a rise, then fall in chloro fluor when a leaf is moved from darkness into light => Kautsky effect.So there are some tricks done with light to make sure that isn't what is being measured. Link to comment
Andrea B. Posted October 15, 2014 Share Posted October 15, 2014 Here's a cool Chloro Fluor gadget called the Handy Pea. And more about how to measure a leaf.http://www.hansatech...2/Handy-PEA.pdf In the specs for the Handy Pea I finally see some information:Illumination: Focused array of ultra-bright red LED’s with NIR short pass cut-off filters.Peak wavelength 650 nm. Spectral-line half width 22nm.Max intensity at leaf surface 3000μmol m-2s-1 Detector: Fast response PIN photodiode with RG9 long pass filter.Added: That is a 720nm longpass. So chloro IR fluor is red-induced IR fluor. Link to comment
colinbm Posted October 15, 2014 Author Share Posted October 15, 2014 Thanks Andrea & Bjorn, glad you like the links & info.I will be trying the IR fluorescence out too, thanks for the fine details Andrea....."So chloro IR fluor is red-induced IR fluor."CheersCol Link to comment
Andrea B. Posted October 16, 2014 Share Posted October 16, 2014 It will be fun, Col. Go for it !! Can't wait to try myself, but I'm caught up in domestic & social duties currently. Maybe I can find a couple of hours soon - and a dark closet. Link to comment
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