Damon Posted February 17, 2015 Share Posted February 17, 2015 Do you know of something that can be easily obtained & put on a bench and shot at with a UV camera setup to test for the efficacy of a UV lens? I may be coming across a bunch of older Canon lenses & I keep killing off my flowers from UV saturation. Nothing alive please. I read some of Enrico's site, which is amazing BTW. Every time I go there I am reminded on how much he has experienced over the years. Kudos to you Enrico.If you have not spent time on there you should. If I did, I am sure I would slow down on asking so many newbie goofy questions (that and if I read more of the stickies that Andrea, Bjørn et al. so painfully put together). Anyway, I read that and some of the sticky but was wondering if any new ideas have cropped up.If not, is there something known to reflect UV using a 365nm light, that I can use? Could I smear Sunblock/Sunscreen on a piece of wood for example? Thanks, -D Link to comment
JCDowdy Posted February 17, 2015 Share Posted February 17, 2015 Sunscreens are within my professional scope. I can tell you that the high SPF products which are free of reflective particulate actives like ZnO and TiO2 will look black and those with various mixtures of ZnO & TiO2 look similar to exterior paints that have TiO2. I have thought that a dried flower with a known UV signature might be good to use as a reference. Others have used various filters, such as those we may have in our kits. A UV/IR cut filter or a GG400 should look dark, whereas a UV pass filter should not. Link to comment
Andrea B. Posted February 17, 2015 Share Posted February 17, 2015 There's an interesting question - would a dried sunflower show the UV bullseye?I don't know.We have seen in the field that some flowers have a change in their UV signatures with age. Link to comment
JCDowdy Posted February 17, 2015 Share Posted February 17, 2015 There's an interesting question - would a dried sunflower show the UV bullseye?I don't know.We have seen in the field that some flowers have a change in their UV signatures with age. I had not considered that ageing effect, perhaps freeze dried at peak condition? Link to comment
Andrea B. Posted February 17, 2015 Share Posted February 17, 2015 I don't really know JD. It will be an interesting experiment. I have a bowl of sunflowers here now. So I'll put one aside to dry out. I don't have any way to fast-freeze one. It's below freezing outdoors right now, but that's still not cold enough for freeze-drying methinks. Link to comment
Damon Posted February 17, 2015 Author Share Posted February 17, 2015 Thanks.I kinda thought when I started on this forum I asked if UV signatures were contingent on being alive and I think the answer was that flowers or some flowers retain their sig.I also have a sunflower that I am basically killing but not yet. After another session today (snow day=no work :) I may l also may relegate it for this purpose. -D Link to comment
rfcurry Posted February 18, 2015 Share Posted February 18, 2015 I used a sectioned pill container with Magnesium oxide, Zinc oxide, Titanium dioxide, and IIRC, Magnesium carbonate. That gave me, at 365nm, a strong white (MgCO3 - 81%), a very strong white (MgO - 94%), a very dark blue (ZnO - 4%), and a dark blue (TiO2, anatase - 31%). The powders were pressed into the container and kept safe with the hinged caps. I hope that helps. Visible light on left, UV 365nm reflection on right Link to comment
enricosavazzi Posted February 18, 2015 Share Posted February 18, 2015 I remember taking test pictures of a (perhaps) Zinnia naturally dried in open air and shadow (=indoors), and the UV pattern was still visible. I don't know how durable that will be, especially if exposed to light. Link to comment
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