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UltravioletPhotography

First attempt in an UV portrait


DonPilou

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Good morning,

After having spent a lot of time to read articles in this forum, here is my first attempt in an UV portrait. I have finally found a compatible lens, the Revue 135 F/3.5, to realize this one.

 

Concerning the weather conditions : the sun was bright and my model in front of it.

 

Gear data :

- Canon 6D full-spectrum

- Revue 135 F/3.5

- Hoya C-500 (BG-39 glass)

- Hoya U340

 

EXIF data : 135mm, F/3.5, 400iso, 1/6s

 

Personal impressions : the effect is here, but my configuration is not optimal at the moment. The camera was put on a tripod, the lens is too long and its aperture is not satisfying. Moreover the combination of 2 filters implies that the transmission is not as good as the use of one dedicated filter like the Venus one. So I am going to buy the Nikon E 50 F/1.8, which appears to be very sharp, and a Venus filter at 52mm. Do you think this is a good investment?

 

Thanks!

post-112-0-35712100-1460705428.jpg

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The culprit in this setup might be the filter stack as the BG-39 probably cuts too much into the passband of the U-340. Perhaps U-360 would be better? The Baader U (last generation) is of course a familiar reference of proven UV quality.

 

The exposure is - very roughly estimated - 4 EV below a UV specialist lens like the Coastal 60/4 or UV-Nikkor 105/4.5. Not very bad but not very good either.

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It is important to define the thickness of each glass in a stack. The thickness of each glass is as important as the type of each glass.

I agree with Bjorn, BG39 is not a good glass to use, because as Bjorn says, BG39 cuts off lower UV.

It is better to use BG40 or S8612.

BG39 and S8612 have the best IR suppression, which is good, but BG39 cuts off more UV.

I see no reason to use BG39 in a stack when you can use S8612 instead.

What is the thickness of each of your glasses in your stack?

Regardless, I would like to compliment you on your UV photo.

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Thank you for your answers. About the Thickeness :

- C-500 : 1mm, T = 90%

- U340 : 2mm, T = 80%

 

As I said, now that I have understood the particularities of UV photography compared with IR photography, I think I have a good vision of what kind of filter I need. So instead of spend money in another cut-IR filter, I prefer buy a full UV capable filter like the Venus filter.

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I don't have C-500 data entered into the calculation program yet.

If you already have U-340 2mm, then you could stack it with BG40 2mm or S8612 1mm. Either would do the same thing.

Stack U-340 2mm with S8612 1.5mm for stronger IR suppression below 1E-04.

Unless you have a better than Kuri lens, then that is all you need, S8612 1.5mm, or even BG40 2mm, or like you say, a Baader U.

 

PS:

Here are some graphs. Sorry, I don't have CM-500 data in the program.

This also shows how even a good UV lens like the Kuri 35mm will truncate the UV filter.

Also beware of China glass, you can't see the difference unless you compare results directly.

post-87-0-07390700-1460730144.jpg

 

Also, be aware that 90% and 80% when stacked and calculated equal something different, since those are the peak amplitudes of those two glass types at those thicknesses,

which when stacked together can often create a different peak amplitude than either alone. Example:

post-87-0-75573000-1460731116.jpg

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Thank you for all these data. Finally I have chosen the Luv 2-U filter by UVIR Optics in 52mm, that will be used with a Nikon E 50 F/1.8. New tests soon ; )
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I would advise you to go for the E. Ludwig Meritar 50mm f2.9. Much better transmission than the E50 from nikon. Also filter size is much smaller. Just make sure you get the preset alu version which is a much better construction than the preset zebra. You can get it in exa mount for £30-50 and there is an exa eos adapter, however you have to be careful and you can't use it on full frame cameras die to the size of the mirror and the structure of the exa mount. You can try to find it in m42 mount (they usually selling the zebra version, which has the same optical qualities but not the same build).

I find the Nikon E50 to be a quite weak performer for uv

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