Sunday, April 12, 2009

Experiment 10: Infrared photography and Microstock








I've been experimenting lately with infrared photography as I did previously with HDR and see if eventually such pictures are accepted and sold on the main microstock agencies.

  • How does it works ?

Light is an electomagnetic radiation with visible light made of wavelenghts in the 400-700 nm and infrared light in 700-1200 nm range (near infrared). Longer wavelenghts will fall in the range of mid-infrared and far infrared (used in thermal imagery) just before the microwaves.

The IR filter placed on top of the lens blocks most of the visible light and let near infrared hit the CCD. Unfortunalely, IR sensitivity is decreased quite a lot by the hot mirror placed on top of the CCD sensor which job is to protect it :(


  • Why infrared photography ?

Mainly because it gives a dramatic, surreal effect to the pictures. Foliage and grass have the property to reflect infrared radiations and appear much brighter in IR giving an ethereal white glow (in some pictures grass can be mistaken with snow). Different foliages have different IR reflectance as well as foliage affected by disease or insect infestation. Blue sky and water will appear dark. Shadows can be interesting in IR with more subtle nuances. Depending on the light, textures can be revealed in more details as well. Skin also can give interesting tones.

  • Challenges in IR photography

Focusing and depth of field


In IR, focusing is different than in visible so producing sharp images can be tricky. If you are lucky your lens have a IR focus mark on it. If not the technique is to take several shots at different focus distance preferably with a small aperture. An universal technique is to use the hyperfocale distance but once again you will have to experiment before to found the settings for your camera.



Exposure


Because the IR filter is very dark, indications given by the camera cannot be trusted and most of time several seconds exposure are needed. I used typically 2 to 15 seconds exposure time so a tripod is necessary. On the positive side, long exposure can give interesting results on water and clouds for example.



Equipment


You will get variable results with IR photography as it depend to what extent your CCD sensor is IR sensitive: most manufacturers add a IR blocking filter (also called hot mirror) in front of the CCD ! It looks like that few year back the protection was not so high…..

Also it depends on the lens : some lenses are known to cause flares or hotspots in the pictures making them not usuable at all….

  • My gear


I am pleased with the Canon Powershot G9 so far using a Hoya R72 filter on the 58 mm Lensmate lens adapter. To obtain longer exposures, I select the ND function on (3stops) and/or put a ND4 filter (2 stops) on top of the R72.

As its name suggests, the Hoya filter blocks wavelenghts below 720 nm. The cut-off actually follows a curve a 50% is blocked at 720 nm so the filter let pass through a tiny amount of visible wavelenghts.

As the settings I use the hyperfocale distance and follow mainly this excellent tutorial : http://www.flickr.com/groups/545326@N21/discuss/72157603843667732/. I shot raw at 80 ISO to limit noise as much as possible.

Although quite expensive, a lot of digital cameras can be modified to remove the IR filter in front of the CCD and make it possible to take handheld IR pictures.


  • 10 steps workfow

Here is my workflow using Photoshop CS3 and Lightroom started with the raw file. It tend not go for the usual B&W processing to keep some blue sky.

Open Raw with LR2

Set color temperature 2000, tint -50

Remove noise Luminance 60

Chromatic aberration : all edges

Export as jpeg or tiff

In CS3 swap red and blue channels: red 0 blue 100, blue 0, red 100

Image--> adjustements levels blue and green

Image ---> curves define gray point

Import in LR2 adjust hue/saturation on the different channels to get the desired results.

Export as jpeg


  • Microstock and IR photography

Although not popular, IR pictures can be found in most agencies. As the time of writing, a search with ''infrared landscape'' and ''infrared buiding'' as keywords returned 545 and 117 pictures on Shutterstock respectively.Very similar search came up on Dreamstime with 537 and 128 images. Istockphoto is very pickup about IR pictures: ony 137 hits returned for ''infrared landscape'' and 45 for ''infrared building’’ !


The most challenging is to have IR pictures accepted as they tend to be noisier and less sharp and downsizing from 12 to 5 MP can help the picture to pass the inspection.

Despite a high rejection rate, I managed to have some IR pictures accepted at Shutterstock (29), Dreamstime (31), Fotolia (9), 123RF(46). However it seems quite impossible to get those kind of pictures accepted at IS which is reflected by the low amount of IR picture on their database.

As far as sales concerned, two of my IR pictures are in my 10 most popular pictures at SS, I had 9 sales so far on DT but 0 on Fotolia.



IR can be combined with HDR or panoramic stitching to produced spectacular pictures but of course noise has to be kept low somehow. Here is one example below:



Useful links


My IR photos gallery on Flickr: http://www.flickr.com/photos/ldambies/sets/72157616326739659/


Flickr groups dedicated to infrared photography

Digital infrared: http://www.flickr.com/groups/55027594@N00/

Infrared: http://www.flickr.com/groups/infrared/

Canon G9 infrared: http://www.flickr.com/groups/545326@N21/

Infrared UK&Ireland: http://www.flickr.com/groups/infrareduk/

Infrared panoramas : http://www.flickr.com/groups/898089@N25/

Infrared Scotland : http://www.flickr.com/groups/infrared-scotland/

HDR infrared: http://www.flickr.com/groups/92588351@N00/

Converted digital infrared cameras: http://www.flickr.com/groups/lifepixel/



Further reading


http://dpfwiw.com/ir.htm A lot of detailled informations and links about IR photography

http://www.lifepixel.com/index.html Services and tips about converting your camera to Infrared

Joe Farrace. Complete Guide to Digital Infrared Photography. Lark Books, 2006, 160p.





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3 comments:

John Kropewnicki said...

You can also pay to have your camera converted to an IR only camera.

Example if your upgrade to a 5dmk2 you can convert your old SLR to an IR.

just google "SLR IR CONVERSION"

Laurent said...

Hi John,

Yes I read a bit about SLR conversion, apparently no need of tripod anymore !
I should go for a 5D MKII then :)

John Kropewnicki said...

Yeah, if you have an old XT or XTi you can convert it.