My new (old) IR A100…..

I have been sidetracked from blogging over the last few months. But I should have more time to get back into it for a while again…..

I spent August back in New Zealand, and we had a great time. While I was the I picked up a bag of Sony Alpha gear from a Pawn brokers (Cash converters). I was actually only after 1 lens in the bag but it was cheap and they wouldn’t split it up. It included several lenses and a Sony Alpha 100 (in very good condition) extra batteries, charger, CF cards etc so I couldn’t lose on the deal. My son was happy he though he was going to get the A100 but instead I took it to Phototronics (An authorises Sony repair centre) and had them fit a 720nm IF filter.

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Digital camera sensors are inherently sensitive to infrared light btthey have a low-pass filter that block most of the infrared light from reaching the sensor.   You can take infrared pictures by putting a filter in front of the lens that block the visible light and just lets the infrared light through to the sensor.  The disadvantage of this is that so little light reaches the sensor that you end up with a very long exposure times.  Also, with SLR’s you can’t really compose using the viewfinder any more since so little light is going to the viewfinder.  By replacing the low pass filter in front of your sensor with a infrared filter so the camera’s viewfinder still works and the exposure times are kind of normal. But when replacing that filter you need to take the filters thickness into account so you wont have an issues with auto focus.

 

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In infrared photography, the film or image sensor used is sensitive to infrared light. The part of the spectrum used is referred to as near-infrared to distinguish it from far-infrared, which is the domain of thermal imaging. Wavelengths used for photography range from about 700 nm to about 900 nm. Film is usually sensitive to visible light too, so an infrared-passing filter is used; this lets infrared (IR) light pass through to the camera, but blocks all or most of the visible light spectrum (the filter thus looks black or deep red).

When these filters are used “in-camera effects” can be obtained; false-color or black-and-white images with a dreamlike or sometimes lurid appearance known as the “Wood Effect,” an effect mainly caused by foliage (such as tree leaves and grass) strongly reflecting in the same way visible light is reflected from snow. There is a small contribution from chlorophyll fluorescence, but this is marginal and is not the real cause of the brightness seen in infrared photographs. The effect is named after the infrared photography pioneer Robert W. Wood, and not after the material wood, which does not strongly reflect infrared.

The other attributes of infrared photographs include very dark skies and penetration of atmospheric haze, caused by reduced Rayleigh scattering and Mie scattering, respectively, compared to visible light. The dark skies, in turn, result in less infrared light in shadows and dark reflections of those skies from water, and clouds will stand out strongly. These wavelengths also penetrate a few millimeters into skin and give a milky look to portraits, although eyes often look very strange.

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At them moment I haven’t started to adjust the captured imaged to much. In all these examples all that I changed was the white balance and some minor adjustments in lightrooon  (contrast clarity etc) as the base raw files are very red and pink.

 

 

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Another possible problem with Infrared photography is lens flare although in this case i actually like the look.

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