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UltravioletPhotography

Self portrait test


cmoody

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Finally received the 105mm UV Nikkor today. Last week I had modified a Vivitar 285HV flash for full spectrum output, but without a suitable lens to test it on it was hard to see how well the modification worked.

 

So here's me, eyes closed and flash fired from a way away (still a little confused as to whether the flash spectrum from the Vivitar is too strong for small amounts of exposure...according to someone who sells modified flashes I should have had more UV exposure in the 10s I walked from my car to his shop, than from a few bursts of one of his flashes?)

 

I wouldn't say I have ever exposed myself to the sun that greatly. In the summer here in England if I know I am going to be outdoors for a period of time I suncream up, which makes the freckles interesting! - I don't have many at all that are visible normally.

 

Seems to all work?

post-64-0-29490400-1413913622.jpg

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Is that normal in the sense of it looks like a UV portrait, or normal as in the sense it looks like a normal portrait? :D

 

To me it doesn't look normal as I don't have freckles!

 

I should add that as well as the UV Nikkor 105mm lens and modified Vivitar flash, I was using a Baader U filter, so I assume the image should just be 300-400nm light?

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People do look different in UV, so that kind of normality was what I had in mind. Men look swarthy and you are likely to record a surprising amount of melanin freckles.
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I think you would perfectly fit in Cara Philipps' works :D

 

I don't have many freckles but in UV I look like a dalmatian as well ;) I believe it's perfectly normal after a certain age. My experience is that younger people have way less UV-Freckles, probably because of the less "damaged" skin.

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I think you would perfectly fit in Cara Philipps' works ;)

 

I don't have many freckles but in UV I look like a dalmatian as well :) I believe it's perfectly normal after a certain age. My experience is that younger people have way less UV-Freckles, probably because of the less "damaged" skin.

 

What is interesting is that I "did" the whole research team. The person with the least freckles (nearly none!), is the oldest!

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BTW, congratulations on the acquisition of a UV-Nikkor. I hope you enjoy its use and make lots of cool UV photos!!

 

The UVA from the Vivitar flash isn't harmful to the skin. It is UVB which causes tanning and can be harmful in large amounts. But I doubt the flash puts out enough UVB to worry about. You can't get a tan from a UV flash. "-) In long, daily exposure to both UVA & UVB, you would get skin damage.

 

However, the eyes are another matter. Sunlight over a person's lifetime creates cataracts in almost all of us sooner or later. And there can be retinal damage. I strongly recommend never, ever UV-flashing a person's eyes. For an open-eye UV portrait, take 'em out into the Sun.

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If the flash is harmful to the eyes when recording UV, why is it any less harmful when used for conventional photography? I assume here you use an ordinary flash tube, not some specialized, souped-up rig that produces gigantic amounts of UV. How much cumulative exposure do you get from a flash of 100 milliseconds (which is a long flash) compared to a CW source such as sunlight? Safety is of course important, but we need some context here.
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No, most of us are not using "ordinary flash tubes". We are using modified UV-dedicated flashes. Hence the warning.
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  • 2 weeks later...

If the flash is harmful to the eyes when recording UV, why is it any less harmful when used for conventional photography?

Most conventional flashes have an UV filter applied to them with the focusing screen. I've compared two Nissin Di622 flashes for UV, one with the focusing screen replaced by pure glass. The difference is huge.

http://clancode.hu/!uv/nis622_fig3.jpg

 

As for the Sunlight... as it is emitting continuously your eyes adapt to it (changing ISO and Aperture ;)), but just think about it how painful can be when you go out from a very dark room to bright sunlight... With flashes the light reaches the eye as a big burst, therefore it has no time to adapt to it, so your eyes will be "overloaded" for a very short time. How damaging it can be? We are not exactly sure, but I do believe it's better be safe than sorry.

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  • 2 weeks later...
enricosavazzi

On the other hand, many studio photographers prefer to use non-coated flash tube for their large studio strobes, because uncoated tubes give a better color balance (according to their subjective judgement).

 

These uncoated tubes happen to be the same tubes I use for UV photography. I attempted to calculate the UV exposure caused by these tubes to a human studio photography subject, assuming a similar VIS to UV ratio as in sunlight (which seems reasonable comparing the sun and flash tube emission spectra). Total exposure even after a day-long session ofhundreds of shots amounts to the equivalent of tens of seconds to a few minutes in sunlight. However, this is probably not a reasonable comparison, because flash exposure has a peak intensity many times stronger than sunlight. Damage caused by one UV photon to a large organic molecule in organisms is often reversible, if enough time is allowed to pass. If a second UV photon damages the same molecule before it has a chance to be repaired, this damage is much more likely to be irreversible. Concentrating the UV exposure in a short burst increases the chance for two-strike or three-strike damage to the same molecule.

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