Infared with Sony Alpha

Purely for the fun of it I recently purchased a Hoya RM72 filter for my Sony

Alpha. It arrived today and I took a few comparison shots with and without the

filter (tripod, mirror lock-up, etc.). In bright sunlight, a proper exposure at

1/640s @ f4 with no filter required 10 seconds @ f4 with the RM72. The filtered

image was red and noticeably less sharp than the unfiltered image. Upon

conversion to B&W in Photoshop the infared effect on foliage produced the

pleasing visual effect I was hoping for. I'm looking forward to trying this out

in the field once the weather improves and foliage returns to the trees.

 

I'd be interested in hearing about the experience of those of you who have

tried infared photography with the Alpha. Surely I'm not the only one...

 

Thanks,

 

Brett

Did you remember to refocus your lens for IR light? IR and visible light do not have the

same focus points on most lenses, unless they are corrected specifically for IR. If there are

no index marks on your lens, you may want to experiment a bit to find the proper focus

offset from visible light. Better yet, get online and buy and inexpensive Minolta prime lens

with IR index marks.

The sony Alpha has a low pass filter on the ccd which filters out most of the infrared and uv light - putting an ir filter on your lens will give you a very weak ir effect because of this - the lowpass filter would have to be removed to correct both for the soft focus and the IR look your after. Because the lowpass filter sits on top of the ccd it focuses the image slightly above it, removing it will allow the IR image to be sharply focused on the ccd and correct for the fact that IR lighwaves focus at a different plane. Low pass filters can only be removed by disassembling the camera and it is reisky as it can cause damage to the ccd, however, the results can be amazing.

Thanks Mark, that really clarifies the situation. This explains why, after following Andrew's advice above, I could not get an acceptably sharp image no matter where I set the focus point. I was hoping to experiment with IR but I'm not ready to permanently modify my Alpha into an IR machine by removing the lowpass filter.

 

Anobody interested in buying a Hoya 67mm RM-72 Infrared Filter?

In case anyone is interested I have a brief update to my quest for infrared photos with my Sony Alpha. I recently took my camera out in the field and, in contrast to my previous effort, was able to get adequately sharp infrared photos that more or less matched what I had hoped to see when I bought the Hoya RM-72 infrared filter. I think the problem I had before was that after composing and focusing without the filter, I left the lens on auto focus when inserting the filter. This likely resulted in some focus hunt and an out-of-focus image. This time I set focus without the filter, switched to manual focus, inserted the filter, and shot away. Turns out the Alpha takes quite nice infrared photos, provided you don?t mind exposure times around 10-15 seconds at f8 in bright sunlight.