XL-2 and Infrared

[Tim Dolan]

I was just out playing with my XL2 and being the curious sort decided to see how it would work with one of my Hoya R72 IR filters, so I put my EF adapter and my 50/1.4 lens on (figuring it would work if anything did). It did work to a point.

It worked very well for a raw collection in the near IR region, however, since I am still new at video processing, I can't (as in I have not figured out how) do the RGB correction so everything was a panchromatic magenta color, however the leaves turned lighter then the pavement so it was definately picking up the IR spectrum and it was brighter then I normally get with my 10D DSLR. the settings were listed as 1/75 and f3.5 to get useable results, so I should be able to also use any of my f2.8 lenses as well. I don't yet have a 77mm to 72mm step down ring (not that I am yet sure that will work) so can not try the 20x lens by itself with an IR filter, but if they are compatable, plan on getting the step down ring at the end of the month when I visit NY.

Anyway I though it was interesting how well it worked and now just need a way to correct the color back to RGB, like I can do with my still photos.

[Barry Goyette]

Tim...I've always been curious about this...is it possible for you to post a still or two..?

Barry

[Tim Dolan]

Apparently I can't add attachments, so here is a link to the images.

Disclaimer, I have done nothing to the images other then convert to a high-compression Jpeg. They are not up to my usual standards for still photos. And I screen captured a blurry regular image, but given the hassle* I am not doing another anytime soon, It will still show the difference though.

IR image
http://www.longwatcher.com/images/Mi.../XL2_IR_IR.jpg

Regular image
http://www.longwatcher.com/images/Mi.../XL2_IR_EO.jpg

*=apparently windows media player does not like avi files produced via s-video in 16:9 mode and ver 9.0 won't let me screen capture an avi even if it is 4:3.

Hope that helps a bit.
Too dark now for more samples.

[Karel Bata]

Many still cameras employ some kind of low-pass filter placed in front of the chip to reduce false color and moire effects, while an infrared filter suppresses red fringing caused by sensor reflections and fog.

This is probably also the case with the XL2.

You could have a look inside your camera, and -if you dare- temporarily remove the glass filter that sits in front of the chip, if one is mounted there. You should then get a marked sensitivity increase in the infra-red region.

Your lens will never give a toatally sharp picture for infra-red because the refractive index of glass is effectively different for infra-red and visible light (in fact it's different for the different visible light frequencies, which makes lens design such a tough job). Your lens calibration markings will certainly be out - so don't rely on them. Though your autofocus might work well. On the other hand it might spend ages vainly looking for something dead sharp!

Anyone trying this - DO POST YOUR RESULTS HERE!

Make sure to put the filter back in for visible light shooting as your back-focus will have changed, and your colour rendition won't look right.


And - BE CAREFUL!

[Dylan Couper]

That would of course void your warrenty on the camera.