Canon 5D Mk2
Infrared conversion

IR Photography...

Many years ago I looked at some infrared (IR) film shots that a friend had taken - they looked odd, with bright foliage and dark skies. Later, as a geologist I became familiar with multi-spectral imaging and how using wavelengths beyond the range of our vision could reveal 'hidden' information about rock and mineral outcrops.

The use of infrared sensitive TV cameras is now commonplace in nature programs, but few photographers get to experiment with this, since camera manufacturers go to considerable lengths to reduce sensitivity of cameras to IR (it distorts colour rendition for one thing).

The Camera

The camera is a perfectly normal Canon EOS 5D mark 2.

The only change is that the filter that normally goes in front of the sensor to keep infrared light away from the sensor, is replaced by one that only lets IR through.

The sensor pixels still have their red green and blue filters in front of each pixel (the Bayer pattern)

Each of these colour filters let's different amounts of different wavelength light through to the sensor.

Since you've got different responses to different wavelengths, the sensor data can be used to generate 'colours' - although since we're using infrared light, they are entirely 'made-up' colours - they don't exist in reality - how could they? our eyes can't see variations in infrared.

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If you open the shutter and look at the sensor, you can't see the usual shiny surface - it looks black.

Move your mouse over the image below to see.

The conversion costs several hundred pounds, and when it's done, you are stuck with it.

Several companies offer IR camera conversion services for a variety of camera makes and models.

Seeing in infra red - a different world

Here's an X-rite ColorChecker card. It's a pretty standard indicator for colour, and is even used for creating profiles to enhance the accuracy of colour rendition in cameras. (See my ColorChecker Passport review for more details).

It's lit here by a normal Tungsten incandescent light bulb. The photo is white balanced on the light grey patch of the card.

The three dice are coloured with typical dyes you might also find in clothing, whilst the card uses pigment based colours.

Here's the view from the converted 5D Mk2

The colours here are fairly arbitrary, from a RAW file converted in Adobe Camera Raw (ACR)

I found that pushing the white point down almost as far as it would go and similarly a hefty adjustment of the tint slider would even up the 3 channels (which are no longer really R,G or B)

For converting images to black and white I found that different settings worked better, and using a big colour space such as ProPhoto in 16 bit reduced the chances of noise and banding showing up.

Remember that there are no 'correct' settings - you will have to work out what you like the best.

Lens issues

The night time shot below, shows a great bit of lens flare at the bottom. Some lenses work better with IR than others - it's not always the best lenses that work best in IR either.

This shot was taken with an Olympus 50/1.2 manual focus lens on an adapter. Unless noted, all shots in this article were taken at ISO 100

Manual focus? - bad news if you are not used to using it, since AF doesn't quite work. The phase detect autofocus system will focus your lens for visible light - not what's wanted. If you enable contrast detect AF via liveview, then the AF will produce a focused IR image.

The focus point of a lens being used for IR is at a different place than for visible light. Some lenses have IR focusing marks on them, but I generally found live view a lot more reliable for wider apertures.

The shot above shows two other things - the men standing round eating chips were all wearing dark coloured tops, and the person standing in the pub doorway was smoking - cigarettes glow very brightly in IR...

Your lenses will also likely exhibit some form of chromatic aberration.

Lens design is a complex process, and it's unlikely that IR focusing was high up on the design requirements list.

You may be able to fix this to some extent with lens correction tools and adjustments.

The picture below is a much magnified crop from the corner of an image.

Once again it will take some experimentation.

Some results - IR photography

I'm just going to put a few samples up here, with some notes on how they were made. IR photography like this is always going to be somewhat experimental and how you make use of the results will vary with your tastes and eventual use for the images. Note that you could shoot IR video on the 5D2 if you wanted.

First up, I went for a walk down our street...

This is the converted raw file, with minor adjustments to WB/tint/levels/shadows to get a 'balanced looking image - some variations in 'colour' are noticeable.

Leaves reflect a lot of IR, giving the luminous tree effect - you will quickly see that this features in a lot of people's IR photography...

Still in ACR, I've converted to greyscale and added a small amount of 'clarity' or local contrast enhancement.

Note how the sky has lost a bit of smoothness.

It's very easy to push things too far and get visible noise and other image artefacts appear.

Exposures are similar to what you would expect in daylight - sensitivity is lower, but not much.

Below, a more subtly converted scene, where I've used Nik Silver Efex Pro for the B&W conversion.

If you think of the WB adjustments you are making in ACR, they tend to come up a bit short. I open the image and then apply a curves layer - using the grey balance dropper, I can neutralise the overall colour cast against some arbitrary 'white point' and move further from the purple look of the earlier street shot.

Application of some strong curves can bring a more neutral look to the colour range. A vibrance adjustment can then bump up the residual 'colour', but I'm left with a fairly low contrast image.

To fix this, I've also carried out a black and white conversion of the image and left this as a new layer. By switching this layer's blending mode to luminance and adjusting the opacity, I can reintroduce some contrast to the coloured image.

A similar approach brings out some colour variation in this night time shot of Leicester City centre.

Fluorescent lighting does seem to show more colour variation.

Some shots just don't look that different from if I was shooting with a normal camera.

However, IR is probably not so great if you want flattering shots of people (OK, not by my definition of flattering - I have seen some wedding photographers try and get away with it - I remain to be convinced ;-)

Her sleeves and his shirt were black, and the 'white' top, bright red - mascara seems to heavily absorb IR.

Note too the very bright light from the small night-light candle (candles give off a lot of IR proportionally to their visible brightness)

The Canon 8-15mm fisheye (lens review) makes for interesting detail in some woods, but this shot needs to be printed at 3 feet across to get the real feel of the scene.

Unfortunately, the image is nowhere near as detailed and sharp, compared to if I'd shot it on my Canon 1Ds3. The lens isn't optimised for IR use and the longer wavelength of IR light means that diffraction starts to show effects a stop or so earlier than with visible light.

It's a bright (hazy) day and I'm getting used to the fact that green foliage reflects a lot of IR and looks bright.

Did I mention the luminous trees?... ;-)

The leaves below do show up nicely, but I can produce similar effects with software such as Silver Efex Pro for my B&W conversion.

A combination of fixing colour and then overlaying a high contrast B&W layer as a luminance blend gives a bit of punch to the image.

First, a version of the image above.

Colour variation is partly dependent on the lens you are using - some are better than others in not introducing a degree of 'brightness' to the centre of the field. The image below is from using a shift lens and seems to show quite a variation (the centre axis of the lens is towards the bottom of the frame)

A similarly converted image from when the sun is out and a few autumn leaves are on the ground.

Like all IR work, the temptation is to crank the dials up to 11...

Some thoughts and conclusions

When I was first asked if I wanted to borrow the camera, I was interested in two main areas.

First was the purely technical, what were the difficulties of capturing images in infrared and how would I process the sensor data to get usable images out of the camera. How would common items reflect infrared light and how would this be interpreted through the existing RGB Bayer filtration of the sensor.

Secondly, would it be a tool for creating photos I wanted to show, or even use in my day to day professional work as a commercial photographer?

Well it takes practice to get consistently good results. Focus needs care and it helps to bracket exposures to allow for the variable amounts of IR light in a scene compared to what you can see.

The 'creative' aspects of IR photography are more difficult to pin down from my own point of view.

There is that initial burst of enthusiasm for something different - that urge to explore and see just what you can do.

This is familiar to me when I get any new bit of kit (or software). It's what I call the 'new toy' phase ;-) My view is that such testing is probably best confined to non-paying work rather than our business clients.

A less kind observation would be that: 'to the man with a new hammer, every problem is a nail'...

With some 'new toys', such as camera movements (tilt/shift lenses) or the new 8-15mm fisheye zoom, I've found they have in time become essential parts of my commercial photography toolbox. Others, such as HDR, I find need a great deal of care if they are not to become an end in themselves and take over (see my review of Nik HDR Efex, which I do use).

It perhaps won't come as a surprise that I find bright the majority of 'colourful' HDR images tacky and garish - and, just as with the miniature world effect with tilt lenses, I found myself saying, about IR:

1. 'OK, done the luminous trees - now what?'

I've looked around at collections of IR images and do find myself wondering to what amount the bright colours and luminous trees are a crutch to support images that just didn't quite make the mark on their own.

I've not yet seen an IR image where I thought 'wish I'd took that' or wanted a print on my wall (my own personal test of images I admire and like)

This is very much a personal view and I know that tastes differ wildly ;-)

It's been great to experiment with and I really do wish it appealed more to my tastes - it did make me think more about the representation of colour and just how I went about converting my colour originals when I'm working in black and white.

Remember that doing more photography is rarely likely to harm your photographic skills - take a chance and experiment. I may not have any photos to add to my portfolio, but that doesn't mean I didn't learn a lot in the process.

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Other info

For Canon lenses, there is a useful guide to which lenses are prone to producing 'hot spots' in the centre of the frame, when used for IR, at Lensplay
Using an IR filter and Lumix G1 for IR Digital ImageMaker
A gallery of Infra Red images from Mia Lewis

Using IR filters

It's worth noting that you can experiment with IR -much- more cheaply by using an IR pass filter on the front of your lens.

It's fighting against the normal IR cut filter that most sensors have in front of them, so not much light gets through. Expect long exposures and difficulty focusing, but you can at least take the filter off afterwards and use your camera normally.

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