colinbm Posted December 1, 2013 Share Posted December 1, 2013 Hi everybodyAnother test with an Allamanda flower (it is the only flower in my garden that gives a good UV reflection) :DI'll have to plant some Gazania's & perhaps a Lasiandra too (I am not a gardener). This Allamanda is in a studio setting (my laundry) & I have set it up with a 400 watt 365nm UV party lamp. Yes it is big...the globe is as big as a football!My beloved Sigma DP2 had told me that I have opened it up too many times & refuses to go :DSo I converted a Sigma DP1 to full spectrum to try these shots. The extra UV output is an improvement & I can actually see the background now, I focused with a tape-measure. CheersCol Link to comment
nfoto Posted December 1, 2013 Share Posted December 1, 2013 Take care not to fry the poor flower .... If not already done you should try to include UV neutral target(s) in your captures. The Sigma sensor may respond in blue, or the blue results from later processing. I would expect the flower corolla to show up in something else than monochrome blue, but as references apparently are missing, it's hard to tell at present. Maybe converting the images to b/w will be better? At least give it a try. Studio flash units with uncoated Xenon tube is the currently best option for UV studio work, but unfortunately, performance comes with a stiff price to pay.However, don't overlook the possibility of sourcing such units on the second-hand market. The prices then tend to be less unacceptable. Link to comment
colinbm Posted December 1, 2013 Author Share Posted December 1, 2013 Thanks BjornThe Sigma Foveon responds in blue channel only in pure UV light, none in the green or red worth using.This is just processed from the RAW to JPG with just some fine tuning. Over exposed areas gives some pink/magenta artefacts that have been reduced only.Yes B&W will give better fine details.I am working on getting a Sigma dSLR to be more receptive to UV & of course better UV lenses will be nice too.I will keep an eye out for a suitable flash unit.If you want me to post other processed images of this I can, please ask.CheersCol Link to comment
nfoto Posted December 1, 2013 Share Posted December 1, 2013 Not necessary - just curious. Still, the false -UV colours arise from the cross-over sections of the Bayer matrix dyes, not the presence of the matrix itself. So even a Sigma/Foveon should in principle be able to show additional colours in UV unless the RGB layers have vastly different dyes. It is unlike these act as perfect 'brick wall' filters though. Link to comment
colinbm Posted December 1, 2013 Author Share Posted December 1, 2013 Thanks BjornActually there was more in the red channel then I thought. But nothing in the green channel.The Foveon sensor has no colour dyes. It is measuring the wave lengths at three depths in the silicon.http://www.foveon.com/article.php?a=67CheersCol Link to comment
Andrea B. Posted December 1, 2013 Share Posted December 1, 2013 Seems like the short UV waves would go directly to the (highest) blue level in the Foveon ??And not "sink" to the green or red levels ?? Link to comment
colinbm Posted December 1, 2013 Author Share Posted December 1, 2013 Yes Andrea that is correct.I will post atriptych of the three channels later when I get back home. Can I add more pictures in this post or should I start another thread ?CheersCol Link to comment
Andrea B. Posted December 2, 2013 Share Posted December 2, 2013 You may add to your thread as you wish - whatever you think makes sense. If the additional fotos are from the same shoot, then prolly posting additions here makes sense so they can be viewed as a whole to offer comments or suggestions. Col, what converter/editor are you using?Also, I would love to get my hands on a raw Foveon foto. Do you have a drop area where you could upload one for me to play with? We used to use the free account on YouSendIt.com for this but they seem to have changed to become a paying service. I'll try to find a free one if you don't have one. But, no prob if you don't have time to do this!! Link to comment
nfoto Posted December 2, 2013 Share Posted December 2, 2013 Hightail.com is the new name for yousendit.com and the basic service (up to 50 MB transfers) is still free of charge. Link to comment
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