More shots with the infrared flash

Started Feb 24, 2008 | Discussions thread
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ellarsee
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More shots with the infrared flash
Feb 24, 2008

These pictures are being posted to share an interesting technique that I'm developing, not to show off the photographs. Standing on their own, the photographs are decent, but I didn't get any outstanding shot. However, for capturing people in motion, in a dark room, without blinding anyone with a flash, the technique shows promise.

Last night I took my dual IR-filtered flash setup http://www.flickr.com/photos/ellarsee/sets/72157603964360673/ to friday night blues
http://fridaynightblues.com

Some shots were taken at ISO 3200 using available light as a comparison:
http://www.flickr.com/photos/ellarsee/sets/72157603973167823/

Some were taken using the IR flashes:
http://www.flickr.com/photos/ellarsee/sets/72157603969444018/

I also converted everything to black and white:
http://www.flickr.com/photos/ellarsee/sets/72157603973199811/

I'm getting a lot of noise even shooting ISO 800, I suspect that it might be from color channels that aren't getting tickled by the IR, if I were to know more about post processing I might be able to clean them up a lot. Alternatively, maybe I should give up an just go with ISO 3200 in low light and stop the camera down more.

These were all shot with a Pentax K100Ds using the FA31ltd f1.8 lens. Looking at them I should also try using my 50mm f1.7

I've pretty much given up on focusing, I just preset my focus to something that seems to work and snap away. I'll manually adjust the focus, then nudge it about 1RCH (a machinists/carpenter term that means a small amount) to compensate for the IR focusing differences.

If I'm shooting available light, I'll shoot ISO 3200, 1/6 sec, f 1.8. With the flashes I was shooting ISO 800 1/20 sec f1.8. So using the flashes made a big difference.

At some point, I'd like to make a flash that pulses a bunch of 735 nm Infrared LEDs for about 10-20 mSec (1/50-1/100 Sec) rather than just filtering the electronic flash with #87LEE polyester filters. The near IR should focus a lot closer to visible, reducing the fuzzy glow. I suspect that there's a market for an "invisible flash" that'll work for augmentation in low light situations.

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