More infrared photography

Well today is Boxing day, and the sun just managed to struggle its way out of the clouds around 14:00. As luck would have it, my variable infrared filter actually arrived from Shenzen late Christmas eve. So, following on from my early IR adventures on Christmas Eve, I thought I’d pop out to our backyard this afternoon, and try a few more infrared snaps. 

The camera is an elderly Lumix GH2, that I had converted to ‘full spectrum’ for IR photography, by Protech Photographic in Crowborough. The camera was sitting in a drawer doing nothing. I’m surprised at how good the results are. As it happens I’d kinda forgotten just what a nice little camera the old GH2 really is too. For those considering doing this for the first time, the are quite a lot of GH2’s on eBay in the £120-£200 range if you don”t want to risk something more expensive. And Kelvin @ Protech seems to rate this sort of camera fairly ease of conversion.

Fourth Eye variable IR Filter in action

Firstly, I thought readers considering using a variable IR filter for infrared photography might find this little animation useful. Basically I mounted the camera on a tripod, then took a snap at each of the variable IR filter’s eight settings. It goes from filtering out light shorter 550 nanometres (filtering-out greens blues and violets), in stages, through 560nm, 590nm, 630nm, 650nm, 680nm, 720nm to 750 nanometres (finally filtering-out the entire visible spectrum). All the images that comprise this animation are virtually SooC (straight out of camera). I.e. no colour editing or sharpening. 

Camera sensitivity was set to ISO 800/30°. The camera custom white balance was configured to give pure greys at 750nm. I find this makes it obvious what ‘visible light‘ colours are being allowed through the filter at any given filter setting. It also gave me a chance to see how closely this filter behaved compared to its supplier’s advertising claims.

I’d say its results are pretty close to the claims. My images images are little more yellow, though I think that is a camera/white-balance issue. In any event, that is too trivial to contemplate here, and mostly irrelevant for producing final images because these will almost always require some palette rotation in post-production anyway.  I would add that there are several Youtube videos slagging-off these variable filters. I cannot reasonably comment on other photographer’s technical difficulties. All I can say is that on my on converted µ4/3 mirrorless camera, this particular variable IR filter seems to work flawlessly. It is also worth noting that this sort of filter is only effective on “full spectrum” cameras.

Some examples

I then opened the image taken with the filter set to 590nm in GIMP. I first used GIMP’s simple White Balance tool… 

Then I rotated the colour palette using its excellent Hue and Saturation tool…

More sophisticated examples

Well, as sophisticated as one can be snapping away in a tiny backyard. These were taken at 590nm. I then used GIMP’s Hue and Saturation tool several times to rotate only selected parts of the colour palette. Note, these were taken in the middle of winter. So the camera was angled in such a way as to avoid seeing through windows of adjacent properties, that might be visible through the naked trees…

Without the IR flter

I also bought a cheapie UV+IR blocking filter, that purports to restoring a “full spectrum” converted camera back to normal. It’s not perfect (well, what do you expect for a tenner?). But it does a surprisingly reasonable job. Firstly with no filter at all, camera white balance set to ‘Auto’…

Then I fitted my cheapie Fotga UV+IR blocking filter, camera white balance still set to ‘Auto’…

I think the Fotga UV+IR filter does a pretty good job of restoring the colours to a full-spectrum converted camera, certainly in this instance.

My current IR kit

It’s an elderly full-spectrum-converted Lumix DMC GH2, c/w a bog-standard Lumix 14-42mm “kit lens” c/w step-up ring and 58mm Fourth Eye variable IR filter, mounted on a 30 year-old British Benbo Trekker tripod, with an “Arca Chinese” quick release. I figured that out of all my dedicated µ4/3 AF glassware, this lens would be the least clever. I also read somewhere this thing is pretty friendly to “out of band” photography. Although it’s an ugly plasticky brute, it’s actually quite a good lens, as kit lenses go. For the animation, the lens had a focal length of 14mm (28mm 135 equivalent). 

Article wouldn’t be complete without a screenshot of another essential bit of kit, GIMP’s Hue and Saturation tool…

Gallery

All the images used for this article, plus a few extras