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UltravioletPhotography

UV Index


DaveO

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Here in Australia we are within reach of the Antarctic "Ozone Hole" which causes high UV levels during Summer (December - March) so that the Bureau of Meteorology issues UV alerts daily during the danger period.

You may find this of interest on this link http://www.bom.gov.au/uv/index.shtml

 

It shows that UV intensity varies with month of the year and time of day.

 

Dave

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Hi Dave

We get some good doses of UV in Queensland, sometimes up to UV Index #12 during summer.

I don't know if there are any affordable UV Index meters ?

I would like to have a UV meter that shows the UV Index & the wavelengths quantities too.....if such an instrument exists & is affordable ?

Cheers

Col

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These UV maps are so interesting. I haven't seen anything like that here in my part of the US. We do see the UV index posted on some weather sites.

 

Col, UV meters exist. Don't know how affordable they are. Let us know if you find one, OK?

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You have wandered into a subject that is within my professional scope. (key ominous music -or- laugh track as appropriate)

 

The UV-Index (UVI) is based on the human sunburn response, technically an action spectrum for UV-induced erythema on human skin (ISO 17166:1999/CIE S 007/E-1998).

 

This erythemal action spectrum is heavily weighted to the shorter more sunburning wavelengths and decreases sharply with longer wavelengths dropping nearly 3 orders of magnitude from 298nm to 328nm and then gradually declining slightly more than another order of magnitude to 400nm. Here is a typical plot versus a solar spectrum showing the resulting erythemal (sunburning) weighted solar spectrum.

 

As you can see the effective weighted spectrum, which UVI is based on, is nothing like the response of a UV camera which is basically the transmittance of a Baader-U filter multiplied by the wavelength response of the sensor array.

 

A better meter for UV-photography than a UV-Index meter would be a solar blind UV-A meter, since we are mostly imaging within the Baaader-U transmittance band. The term solar blind in this context meaning insensitive to Vis/IR. There are a lot of inexpensive UV-meters out there but most of the cheap ones are not solar blind and you cannot trust claims to the contrary.

 

A good handheld research grade UV radiometers can cost more than a nice camera. However an acceptable affordable broad band UVB+A radiometer exists from a company I can personally vouch for as my lab owns several different models of them. They are not much larger than a deck of playing cards so would be no trouble to add to your camera kit. I see there is an Australian distributor, I expect they do a good bit of business Down Under given your proximity to that troublesome Antarctic ozone hole.

 

G'Day Mates!

Ain't that what y'all say? :)

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o man!! That is a cool gadget for sure. Thank you bunches, JD !!!

 

This goes into the Stickety Stickah.

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