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UltravioletPhotography

New UV Lamps for Ultraviolet Photography


colinbm

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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.

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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.

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Chlorophyll a fluoresces around 673nm and 735nm.

See: http://en.wikipedia....iki/Chlorophyll

and 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

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Chlorophyll fluorescence - a practical guide by Maxwell & Johnson

http://jxb.oxfordjou...9.full.pdf+html

But 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.

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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.

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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."

Cheers

Col

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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.
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