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Infrared Photography

This article is an updated translation from the German Magazine Kwerfeldein from the 20th August 2011.

A few years ago, I found some very strange photos on DeviantArt which looked totally different from the usual images. Incidentally, they were popular, achieved good reviews and interesting comments. I wanted to know more...I asked gilad and MichaelMagin for some advice and began to experiment with the technique myself. I started out with great enthusiasm and my initial results were pleasing. It turned out that this extraordinary photographic technique is actually very easy to achieve!

The Technique
Light waves start in the invisible short wave UV region and become visible to the human eye on the frequencies of about 385 to about 789 THz. They go further into the invisible long wave infrared range. Despite what the name may imply, Infrared photography is concerned with that invisible long wave light just outside of what our eyes can see; it is not directly related to the thermal imaging technology that most people think of when they hear "InfraRed". In infrared photography, a green tree or green meadow appears bright-white instead of green this is know as the so called Wood Effect and it changes the deep-blue sky to nearly black blue with fine gray blue gradients. White clouds that would normally appear muddy gray jump out with strong contrast and depth. Everything appears more magic - like pictures from an alien world.

The 950nm filter

So how do I change my digital camera into an infrared camera which shows this invisible light to our eyes, and achieves these magic white snow effects? The cheapest way is probably a 950nm (nanometer) "No Name" filter from Hong Kong (usually available on eBay for about 20 € ($25 USD). The filter diameter should fit exactly on your most commonly used lens. The diameter of filter you need in millimeters can usually be found printed on the front of the lens. The filter comes after one or two weeks by air mail. For most infrared experiments this filter will do just fine. Or you can order an expensive infrared filter (e.g. the popular Hoya r72 = 720nm) for between 40€-60€ ($45-$70). There are other filters and filter systems in various sizes and thicknesses. Not every infrared filter is suitable for each camera or lens.

For my part, I ordered the inexpensive 58mm "No Name" 950nm filter from ebay Hong Kong for my Sony F828. It blocks absolutely all visible light and it still works flawlessly today.

My Sony F828 has the advantage that the inner infrared blocking filter or "hot mirror" - which is static in most camera models - can be easily folded away in the NightShot mode. This makes the camera highly sensitive to the full spectrum of light instead of trying to mimic what the human eye sees. It also helps the camera take shots with minimal light or even in complete darkness because a small infrared LED is fitted below the flash. This allows the full spectrum of light to fall freely on the sensor in NightShot mode, which allows a preview image to be visible on the camera's LCD. However, I don’t use this infrared LED because it produces some disturbances within the picture.

The next step is to put the IR filter on the lens and when I do this I see a pure monochrome green infrared image on the monitor of the camera. This image is somewhat similar to the green "news pictures" of the terrible war in Iraq. In other camera models this might produce a red monochrome infrared image. Despite this strange green initial image, the 950nm will offer you a wonderful black and white image after post production. Color images can be only created if you add different combined color levels during your post processing.

The 720nm filter

For camera models without NightShot mode, Hoya r72 infrared filter (720nm) is recommended. This filter creates a color "hybrid image" of infrared waves and visible light. These photos also depend on post production. Photoshop is ideal because you can just replace the red and blue channels in the Channel Mixer. When this is made sensitively, with slight variations to the red and blue channel levels (around 100% but can be more or less) a fantastic lovely blue sky and white and purple trees can be achieved. Subsequent Level adjustment reinforces this color effect considerably.

The Hotspot

Unfortunately, in some camera models or lenses with a front mounted infrared filter you may see a bright circular unpleasant hotspot in the center of the image. This can be circumvented and there are many places on the internet that deal with this issue in detail and show tables of which camera or lens tends to form a hot spot. You may have to do a bit of Googling to find out the suitability of your own camera and lens.

White Balance
If your camera has the ability to correct white balance, this will be very useful for infrared photography. With the infrared filter on the camera, just look at a green tree or green meadow and correct the balance until those green colors are white. If you like to work with RAW images these corrections can be made later with Photoshop in the post production.

Tripod
If your camera doesn't have Nightshot Mode, your IR filter will "slow" you camera down significantly. That will mean long exposures, and for all long exposures (i.e. 30 seconds or even just half a second) it is best to use some kind of tripod. Handheld photos are possible from 1/15 second or 1/30 second or faster as well as in the Nightshot Mode. You can achieve faster shutters with high ISO or with converted cameras. Lower ISO (64 or 100) will mean less grain in your photo which is generally preferred.

Converted Cameras
Anyone who places high demands on infrared photography will certainly someday want a camera that has been converted for this purpose. Basically you can choose any digital camera to convert into an infrared camera. Basically, you just need to open the camera and remove the infrared blocking filter and replace it with an infrared filter on the sensor. This is a highly complicated practice, and if you do not want risk destroying your camera, you should definitely leave this kind of work to the experts. Two private professionals who convert cameras quite inexpensive are Rainer Hönle (info@gletscherbruch.de - Germany) and Ilija Mel (ilimel2@gmail.com - USA).
ilimel is also a member of r72 Infrared Group.

A converted camera has the advantage that it can practically be used like a "normal" hand held camera. However, in modern "fancy" expensive camera bodies you should always switch off any automatic functions and adjust the focus and exposure manually because the "normal" values will change when using an infrared filter.

Program Mode and autofocus no longer function normally with infrared filters. Your lens barrel may have red markings which indicate the distance correction for infrared images (Lenses tend to be "short-sighted" with infrared filters). The automatic exposure functions will also go "crazy" because your camera is programmed to compute exposures based on the middle of the visible light wave spectrum. You will have to experiment a little bit to determine the optimal settings for your camera.

Additional filters
In strong sunlight, it helps to add an additional 4x or 8x medium density filter to avoid glare. This is especially important in very high contrast or harsh sunlight situations to avoid fringed clouds and "blown-out" surfaces. These filters help to balance contrast contours. But this is not unique to IR, as you may know, it is also the case in "normal" photography.

So - all very simple?

Many things that are described here might sound complicated and very technical at first. Also, some Internet infrared tutorials may be intimidating. However, in practice the infrared technique is much easier; if you experiment, you will find it comes pretty naturally. You may discover that in the late afternoon the infrared rays from the sun are the strongest. A 90 degree angle of the sunlight brings more depth than back lighting (i.e. shooting into a sunset). However, backlighting can have its appeal. So ...don't be intimidated... try it yourself. It is certainly fun to do something in a new and experimental way!

By MichiLauke (Michael Laukeninks)