Incense

by Bart Arondson

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NOTE: there have been many edits to this question as I understand more and more, so answers might not be totally relevant to the question, sorry for this all...


My concern is: all the current flash equipment uses Xenon flashtubes. I have been reading about the hazards of using these flashtubes (e.g. http://donklipstein.com/xesafe.html#u). Indeed, Xenon tubes are used for killing bacteria and germs, and can cause severe permanent damage in the eyes.

I see photographers casually discussing whether they are going to use UV-coated domes or tubes just to get better pictures of white dresses. However, I am a bit confused.

Is there an official definition of the wavelenghts allowed for UV-coated and non-UV-coated?

I would rather not blind any people or models by using hard UV...


EDIT: After Caleb's answer, it seems that I got the UV-coated backwards...

And in general, I looked further. So there is the option of a dome being UV-coated or not UV-coated. Another issue is the glass itself, whether it is a clear glass or frosted, to decrease color temperature by ~600K.

So right now I am concerned about: using a clear glass dome without UV-protective coating.

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The question is not entirely clear. What sort of answer are you looking for? What do you mean for example with Can it happen that some tubes advertised as "UV-coated" actually manufactured for UV photography? Please revise your question such that it becomes clear what the question is exactly and try not to ask more than one question at a time. If you're interested in overall flash safety this is slightly relevant. If you're interested in differences between flash domes, ask exactly that. –  Bart Arondson Dec 23 '13 at 12:28

2 Answers 2

I see photographers casually discussing whether they are going to use UV-coated domes or tubes just to get better pictures of white dresses.

I think you misunderstood. From what I've read, wedding photographers particularly want to avoid bright ultraviolet light when photographing a wedding dress because the UV can cause the brighteners added to fabrics to fluoresce, giving the dress an unwelcome blue cast.

It seems that "clear" is between UV-coated and frosted, and it seems that UV-coated emits more UV.

I believe that's backward. The UV coating is supposed to reduce the amount of UV and avoid the fluorescence problem; see What does UV coating do for a flash tube? for more.

Also, note that this is mostly only an issue when talking about larger strobes, like studio units. Hotshoe flashes (a.k.a. Speedlights or Speedlites) typically have a plastic lens in front of the tube that will block UV light.

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Thank you for your clarification. Yes, I am talking about studio heads. –  TFuto Dec 24 '13 at 14:58

The duration of a photographic flash is so short, any effects will be short lived, and not permanent. Most sensors on modern DSLR cameras have IR filtering, so really, what's the point? Shoot/view. Not white enough? Change the white balance. Shoot/view.

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The first sentence doesn't make much sense. Short duration doesn't necessarily mean the effects aren't permanent. A hammer strikes a nail in an instant, but the nail doesn't (usually) pop out afterward. Likewise, a flash of light can certainly cause lasting effects if it's bright enough. I expect you meant something like "even though it's very bright, the duration is short and so the total amount of light delivered is not enough to cause lasting damage." Even so, it'd be helpful to cite a source to justify such a statement. –  William Shakespeare Dec 23 '13 at 20:13
    
Yes, if the duration of a flash of light is as short as a photo flash generally is, then not enough photons will be fired towards your subject to cause any permanent damage. Of course, all bets are off if your photo tube is powered by anything more than a bank of batteries, and the duration goes beyond a mere fraction of a second. Staring into the sun will blind you. Looking into the sun briefly will not. You Caleb are perhaps picking nits. –  Mike Gilchrist Dec 23 '13 at 21:22
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I'm not nitpicking; exposure is related to both duration and intensity. You can't say that exposure is minimized just because duration is short, especially when talking about strobes which are incredibly bright. Further, the OP doesn't seem to be asking only about speedlites -- studio strobes with much larger power supplies, and which often are used in larger numbers, are fair game. I'm not saying that you're wrong, just that your answer doesn't provide a useful justification/explanation. –  William Shakespeare Dec 23 '13 at 22:11
    
Your second statement in your last post is flawed. Duration has everything to do with electromagnetic exposure. A controlled release of x-rays through the body will image bone and tissue. If you unshielded the radioactive source, you could receive a lethal dose very quickly. –  Mike Gilchrist Dec 23 '13 at 22:38
    
That's exactly my point -- it's a rate problem. Total exposure in both cases is the product of the rate, which is the intensity or brightness of light/radiation, and exposure time. 1 unit/sec for 1 sec and 1000 units/sec for 1/1000 sec both give the same total exposure. This is why it's not enough to claim something must be safe because the duration is brief; you have to consider the rate of exposure as well as the duration. –  William Shakespeare Dec 24 '13 at 18:44

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