Just some stuff about photography


Infrared photography with the E-1

in Olympus E-System , Thursday, November 18, 2004

Ok, I haven't written anything in this so-called blog for ages, but actually I've got a few things in the queue. The first is a brief write-up on using the E-1 for infra-red (IR) photography. Why IR ? Well it certainly gives a different perspective on things. Infrared photography uses either IR sensitive film, or an IR-sensitive digital sensor, to record an image at light frequencies lower than the human eye can detect, and to present a rendition of the scene which we can see. I have the distinct impression that whilst IR film is specifically designed to do this, digital camera sensors more or less do it despite the design. Most, if not all, digital cameras include an IR filter, I believe to reduce noise. This means that some are totally insensitive to IR, and those that are not require long exposure times, essentially to allow the light to leak past the filter. However, when IR photography does work with a digital camera, it has several advantages over film. First, IR film is very grainy (although some would not see that as a disadvantage). But the second is significant - you can check the exposure immediately after capture. This is significant, because exposure of IR film is largely guesswork and experience. There are no IR-sensitive lightmeters that I know of. A third advantage is the fact that you don't have all the problems associated with loading and developing IR film. wisteria1.jpg This image is a photo taken with Kodak High Speed Infra Red film, using a Hasselblad Xpan. The standard characteristics of IR photography can be seen - the bright vegetation, the other-world effect, and in the case of film, the very coarse grain. Note that this photo was taken handheld, probably at around 1/60th second at f8 or thereabouts. The same photo with the E-1 would take somewhat longer. A number of different IR filters are available on the market. Some allow a small amount of visible light through, giving a deep, dark red effect. But "real" IR filters are blocking filters, so called because they let no visible light through at all. They appear black to the human eye. I tried two IR filters on the E-1, a B&W 093, and a Hoya R72. The B&W was too dark, but the Hoya works well provided long exposures are used. It goes without saying that IR photography with the E-1 requires a tripod, for two reasons - one the long exposure, and two, you have to frame the shot first with the filter off. Some digicams, such as the Nikon Coolpix 950 (still highly regarded by the IR community), allow you to preview the image on the screen. After a bit of trial and error, I discovered that on a reasonably sunny day - and you need sunlight for IR photography - using the Hoya filter requires exposures of between 45 and 60 seconds, at apertures between f4.5 and f11. I also quickly discovered that at such exposures the E-1's sensor shows a lot of thermal noise. Fortunately, switching on Noise Reduction fixes this, although at the cost of doubling the exposure time, which really taxes the battery. ir_compare_1.jpg The two images above are 100% detail from a scene shot without noise reduction (left) and with (right). The image you get, after all this, is very red. Since the effect we're after here is to duplicate black & white IR film (colour IR film is another story altogether), we need to convert this to black and white. First of although you need to convert it from RAW (I don't recommend shooting JPG here). Don't use C1 for IR shots - obviously its well document difficulties with reds have a field day here. Use Photoshop ACR or Viewer/Studio, and ideally just go at default settings. If you use Photoshop ACR, you might see that the red channel is way overblown. Don't worry, but pull it back a bit using Exposure. Next, converting to black & white: Photoshop has several tools for converting to black and white, the most obvious being Desaturate. Don't use this. Use the Channel Mixer, preferably as an adjustment layer. The actual values you dial in to the Channel Mixer are a matter of taste, but generally most useful information is in the Red and Green channels - Blue is pretty noisy and dark. channelmixer.jpg The image below was taken with the E-1 is bright afternoon sunlight, with an exposure of 60 seconds at f/11. In this case arguably it was slightly over-exposed. It was processed using the Channel Mixer settings shown here. Arosio_041117-000096.jpg So, in conclusion, IR photography with the E-1 works and is good fun. Long exposure times mean that you will need a still day, or will accept (or welcome) wind motion blur effects. It is different to film IR, but well worth exploring it its own right.