Questions about UV fluorescent photography
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Re: Questions about UV fluorescent photography
As a cautionary note, at least with my Nikons you generally need to dramatically underexpose to not blow out fluorescence (this varies by the color of fluorescence of course). No filtering was applied on the light source or camera side, and along the top/right you can see the natural deep green of this Rogerly fluorite. There is essentially no violet pollution; the brilliant blue is accurate for this particular specimen.
For comparison, here's the same specimen with same settings but natural light alone.
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Re: Questions about UV fluorescent photography
What settings do you use for nominal white balance?physicsmajor wrote: ↑Tue May 31, 2022 12:46 pmNo filtering was applied on the light source or camera side, and along the top/right you can see the natural deep green of this Rogerly fluorite. There is essentially no violet pollution; the brilliant blue is accurate for this particular specimen.
--Rik
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Re: Questions about UV fluorescent photography
In this quasi-studio setup I match the in-camera white balance to the exact Kelvin color temp setting from a trusted bicolor LED panel, which lets me set its Kelvin color temp. I don't change that when adding the 365nm source. Keeping a little dim white light is deliberate, I find this is preferable for most UV work and 'proves' you haven't let the camera WB go off the rails. The fluoro colors captured then match reality in my experience.rjlittlefield wrote: ↑Tue May 31, 2022 12:48 pmWhat settings do you use for nominal white balance?physicsmajor wrote: ↑Tue May 31, 2022 12:46 pmNo filtering was applied on the light source or camera side, and along the top/right you can see the natural deep green of this Rogerly fluorite. There is essentially no violet pollution; the brilliant blue is accurate for this particular specimen.
--Rik
For color rendition comparison, this site has a good example of a Rogerly fluorite under UV and white light https://www.naturesrainbows.com/post/20 ... erley-mine. The UV activity so strong that it gains a blue-teal tinge under sunlight, which is an effect known as daylight fluorescence.
Re: Questions about UV fluorescent photography
Funnily enough, I just finished correcting the final proof of a paper I've written which covers some of what you are seeing here Mark.
With 'normal' colour cameras, there are filters which are supposed to remove the UV and IR before it reaches the sensor. However some cameras do this better than others. My Canon cameras for instance have quite 'leaky' filters especially around 365nm, and this typically produces red specular highlights in UV fluorescence images, while Nikon and Sony are more efficient at blocking this. It looks like you will need an additional filter to block the UV rather than just relying on the ones in the camera. Lou mentioned Zeiss T* filters. I'm glad to hear that as the Zeiss T* was the one I concluded that was the best option to replace the now no longer made Schott KV-418 (at least among the commonly available highstreet type filters).
With 'normal' colour cameras, there are filters which are supposed to remove the UV and IR before it reaches the sensor. However some cameras do this better than others. My Canon cameras for instance have quite 'leaky' filters especially around 365nm, and this typically produces red specular highlights in UV fluorescence images, while Nikon and Sony are more efficient at blocking this. It looks like you will need an additional filter to block the UV rather than just relying on the ones in the camera. Lou mentioned Zeiss T* filters. I'm glad to hear that as the Zeiss T* was the one I concluded that was the best option to replace the now no longer made Schott KV-418 (at least among the commonly available highstreet type filters).
Jonathan Crowther