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UltravioletPhotography

First Experimental UV Photos


SteveCampbell

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SteveCampbell

post-156-0-49534400-1501158671.jpg

 

Three Sisters, Blue Mountains, Australia. 33-photo panorama. Full spectrum-converted Canon 450D (multi-coated fused quartz) + M39/M42 17-31mm helicoid + EL Nikkor 80mm f/5.6 (metal) + BG40 + UG11. ISO1600, 80mm, f/5.6, 1/80 x 33. Photoshop had a really hard time making a panorama from these photos, so I arranged them manually and used auto-blend. I really need a wider lens!

 

I chose this location in order to get the exaggerated atmospheric hazing effect.

 

Still figuring out what aesthetics to use for white-balance.

 

For contrast, the same scene in visible and infrared:

 

http://68.media.tumblr.com/d5abb0589a4b8161c837319ae8eb7264/tumblr_opp0w7dIUr1r85u0oo1_1280.jpg

 

http://68.media.tumblr.com/375904ca486fe5fdda3e20134e7c651c/tumblr_opp1d49Gxd1r85u0oo1_1280.jpg

 

post-156-0-83570700-1501158792.jpg

 

Me. 80mm, f/5.6, 1/60. UV index was 3.2 that day, so things were looking a little dim. My freckles are almost invisible in visible light. I like the people in the background wearing sunblock.

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Amazing place, although when I was there it was raining and the view wasn't quite as nice. Loving the IR shot. So am I right in thinking that by combining BG40 and UG11, you're still going to get quite of a bit of light transmitted around the 650-750nm region?
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SteveCampbell

Thanks! Looking at the transmission curves I can see what you're getting at, although I'm not seeing any evidence of the Wood effect. Any suggestions for filter choice improvement (other than Badaar for $ reasons)?

 

Amazing place, although when I was there it was raining and the view wasn't quite as nice. Loving the IR shot. So am I right in thinking that by combining BG40 and UG11, you're still going to get quite of a bit of light transmitted around the 650-750nm region?

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Andy Perrin

Gorgeous!

 

The white balance on the UV shots looks pretty tilted toward magenta -- is that for artistic effect, or did you just not get all the magenta out?

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SteveCampbell

Thanks!

 

I left the color balance essentially unchanged since it was a rough, experimental photo. My final choice will probably be based on a balance of artistic aesthetics, people's preconceptions of what an ultraviolet photo would look like, and technical accuracy. Probably gray-card calibrated + slight violet/magenta tint. If I can get some more color information out of it that would be fantastic, as it seems a little monochromatic at the moment. For example, with my infrared stuff I'm getting both red and blue due to shorter vs longer IR activating different pixels on the sensor

 

Gorgeous!

 

The white balance on the UV shots looks pretty tilted toward magenta -- is that for artistic effect, or did you just not get all the magenta out?

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Andy Perrin
Well, there isn't much question of technical accuracy with false colors, but typically people take the most magenta thing in the image and do a click WB off it, because the magenta tends to overwhelm everything else. Better methods include taking a UV-neutral target like virgin PTFE (Teflon) and using it to take a white balance either before photographing, in-camera, or to transfer a white balance from it after the fact in a program like PhotoNinja. YMMV, but those are the methods I learned on this site.
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SteveCampbell

The teflon thing is pretty valuable advice, thanks. I suppose that would do nicely to replace a gray card. I suppose you could also set an in-camera custom white balance using that method.

 

Well, there isn't much question of technical accuracy with false colors, but typically people take the most magenta thing in the image and do a click WB off it, because the magenta tends to overwhelm everything else. Better methods include taking a UV-neutral target like virgin PTFE (Teflon) and using it to take a white balance either before photographing, in-camera, or to transfer a white balance from it after the fact in a program like PhotoNinja. YMMV, but those are the methods I learned on this site.

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Beyond the visible realm there may be a measure of arbitrariness in how color is presented, but there is still a difference between actual chromaticity (which encodes information on how the subject matter reflects the waves recorded) and color casts and cast gradients (which encode no such information.) By default, most viewers prefer the second two elements not be present in an image, as they tend to come across as obscuring noise. There are, of course, exceptions, such as tinted and toned monochrome images and "antiqued" color images, but these are special effects which are best used mindfully rather than indiscriminately.
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Thanks! Looking at the transmission curves I can see what you're getting at, although I'm not seeing any evidence of the Wood effect. Any suggestions for filter choice improvement (other than Badaar for $ reasons)?

 

The IR and visible contribution will be much reduced in your image with those filters, but it depends on whether you want 'pure' UV images, of ones which are mainly UV. Given the sensors are more sensitive to IR than UV, anything you can do to reduce IR transmission is a good thing when capturing UV images. The BG39 filters will reduce the IR beyond your BG40 and aren't expensive (last one I got was 25USD for a 52mm one), however it will reduce your UV as well, especially at the lower wavelength end resulting in longer exposures. I must emphasize that I am relatively new to UV imaging myself, so I'm sure some of the more seasoned experts can also provide alternatives.

 

Normal photographic grey cards are no good for UV, as they do not have a flat reflection curve in the UV. Myself and a number of people on here just use some cheap virgin PTFE as a cheaper alternative to Spectralon samples. For instance, here's some analysis I did of my sample to determine its suitability;

 

http://www.ultravioletphotography.com/content/index.php/topic/2268-cheap-uv-white-balance-substrate/

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Andy Perrin

Cadmium (our member, who also sells filters as UVIR Optics and knows the most about filter glass IMO...) recommends these pairings as optimal:

UG11 1mm + S8612 1.5mm to 2mm

UG11 2mm + S8612 1.25mm to 1.75mm

U-360 2mm + S8612 1.25mm to 2mm (1.5mm seems best)

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After the white balance step, we typically see blue, yellow or sometimes green false colours along with the various white/black/grey tones. What false colours you get are highly dependent upon the subject being photographed and the distance from the subject. In a landscape scene, especially at large distances, you sometimes have to pump up the saturation to bring out any lurking false colour (after the white balance is made).
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