North Atlantic Skyline - - Photographs from the west of Ireland (Galway, Mayo, Clare, Limerick, Roscommon and even Leitrim)

Digital Infrared

Forthill Cemetery, Galway City.

I've been messing about with some infra-red photography in the last month or two. I had intended to hold off writing about it until I had more (ok, better) photos to show you, but it seems like every time I go out with the purpose of doing some IR shots, the weather doesn't cooperate (or I forget the filter). I'll say at the outset that all of the techniques and tips mentioned below were figured out by other people (and I've included some of the links below). The point of this post is to gather some of the links together (for my own benefit as much as yours) and also to give a little feedback on my own experiments with IR. By coincidence, since I started writing this, there has been a discussion on Flickr relating to some of these issues - if you're a beginner to digital infrared, it's a good place to learn things. As far as I know, there hasn't been a major discussion on digital IR at the Galway Camera Club, though I've seen a few pictures using some of these techniques in some of the presentations.

Experimenting with digital infra-red photography is as simple as placing a glass IR filter in front of the lens and clicking away. Ok, maybe not that simple, but a lot more straightforward than film infra-red photography. I use a Hoya R72 (for a lens with a 58mm width) which will cost you 37 pounds sterling with Jessops. Because the filter is almost black, you need to use a tripod; firstly, because it's likely that you'll need to use a low shutter speed, and secondly, if you're using a DSLR, you'll need to compose the picture without the filter and then fit it on before taking the shot.

Why use an IR filter at all ? For me, it adds a different dimension to black & white photography, though it's not something I'd use too often. The IR filter blocks most visible light, letting just infra-red light through. The effect is that blue skies appear black and green foliage appears white - I don't see it any differently than using red or green filters for 'ordinary' black and white work.

I've used the filter with three different Canon cameras with varying results. I first tried IR with a Canon G3, which is a digital compact camera. One of it's more useful features is its LCD screen which gives a preview of the image. This is great for IR since you can actually preview the IR image. Alas, the results were not encouraging - the photos were very grainy and often lacked sharpness (like this one of a holy well in Inishmicatreer, which is just awful). The worst problem was the appearance of a 'hotspot' (I.e. almost burned out dot) in the middle of the image.

This is a typical example, taken in the 'Quad' in NUIG [This is the 'raw' image before any processing, showing the deep red tint caused by the filter]. It didn't happen in every photo (this one of Annaghdown turned out OK), but a lot of them. This appears to be a characteristic of the lens, and with a digital compact, you're stuck, since you cannot change the lens.

Since the IR filter is almost opaque, very little light of any sort gets through. This means that either you must use a very high ISO setting (which leads to increased graininess) or very slow shutter speeds. My G3 has many great qualities but producing sharp pictures at the highest ISO setting isn’t one of them. Even on a really bright sunny day (best conditions for IR photography), I would usually need to shoot 8-15 sec exposures – this limitation generally forces one to shoot landscapes (and preferably on a day when the wind isn’t blowing). Sunny, windless days in Galway ? Now you know why I don’t get to take IR photographs too often.

Digital cameras are fitted with internal filters to reduce infrared light. It's possible to get them removed - see here and here (though it means that your camera is only suitable for IR photography). Digital compacts seem to be a favourite for IR conversions - mainly because their owners have now graduated to DSLRs and don't mind sacrificing their old cameras. Despite my own lacklustre efforts, pictures on Flickr show that it is possible to get very good results with a G series camera.

A digital SLR has interchangeable lens, so I was eager to try out my IR filter when I bought my 350D. Unfortunately, the kit lens (18-55mm) that is supplied with the 350D also suffers from the hotspot problem. However, the Canon 75-300mm lens does not, and takes perfectly acceptable IR photos (including this one and also the shot below of Menlo Castle.

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However, a telephoto zoom is not the best lens for landscapes. I also have a wide-angle zoom (the Sigma 10-20 mm) – but it has a 77mm thread and I didn’t feel like shelling out for a second filter. [I did test the lens to see if it suffered from a hotspot by taking the circular lid of a plastic container, cutting a 58mm hole in it and, using loads of gaffer tape, fixing the IR filter in the middle of it. From what I could see, the Sigma doesn’t suffer from a hotspot. And yes, that 'adaptation' was every bit as brutal and crude as it sounds].

I recently bought a EOS 5D – unfortunately, the lenses that I normally use with it (24-105mm and 100-400) have 77mm thread. But my old [film] EOS has two [fairly cheap] Sigma lenses – a 28-105 and a 70-300. These lenses don't work on my EOS350D but they do work on the 5D. And they don’t have hotspots either! The 5D has another advantage too – the images that it produces at high ISO are damn near faultless [what I mean is that they are sharp and grain-free – rubbish compositions are still my responsibility!]. Since I can use up to ISO 1000, it means I can set a relatively high aperture (say, f11) and still keep a reasonable exposure time (say 6 – 10 seconds). The longer the exposure time, the more likely it is that more of the image will be blurred. [Taking photos in Eyre Square, the biggest problem were those poxy crows that ruined about half the shots by swooping into view – you’d swear they were doing it deliberately]. Because of the high quality of images taken at high ISO, it would be possible to take photographs at relatively high shutter speeds (i.e. 1/30th of a sec) using a fast aperture. I don't have any examples of this here.

If you use normal metering, the photos tend to have a strong magenta tint. To avoid this, you should set a Custom White Balance. Most cameras allow you to adjust the White Balance on images. There are usually settings for fluorescent and tungsten lighting and it's also possible to set a custom function (even my G3 compact can store two separate custom settings). I must confess that I didn’t pay too much attention to this function until I saw how other IR photographers had used it - the main reason I don't use it is that I usually forget to turn it off afterwards. Setting a Custom White Balance (CWB) for IR can be done by pointing the camera with the IR filter at some grass (ideally, you'd use an 18% grey card or something else that's reflects an 'average' exposure) and taking a shot. On Canon cameras, there's a menu option to select that picture that acts as your CWB. On subsequent photos, this shot will be used by the camera to determine the black, white and grey levels in the shot. As you can see, the resulting picture is visually pleasing even without adjustment in Photoshop.

Of course, it's one thing to take a photograph, and another to produce a finished image in Photoshop. There are plenty of sources of techniques and pictures on the Web. As I mentioned before, the Flickr digital infrared discussion group (and there are plenty of pictures to look at) - it's a good starting point.

If you Google for digital infrared photography, you'll get a bunch of useful links that describe basic processing techniques. Sites such as Infrared photography with a digital camera , Shooting Infrared with Digital Cameras and Digital IR Choices are a good start. Prior to getting the 5D, I would convert the IR image to black and white (by using either the Desaturate or Convert to Greyscale options in Photoshop). Since I've started using the CWB on the 5D, the image from the camera does not have the red colour cast, so less adjustment is required.

Another interesting technique is to combine both an IR and normal picture within the same image. This enables elements of a colour picture to be combined with the ethereal characteristics of a monochrome infrared image. John Beardsworth has an excellent guide to the technique here (another description here). Here is an example below

Beech tree, Portumna Forest Park, Co. Galway. The original colour shot is
here and the original IR shot is here.

Going one step further is Michael Sullivan, whose dramatic infrared photos show how far you can take the technique . Have a look at Rock of Cashel and an Irish graveyard.

To summarise, the Canon G3 suffers from IR hotspots (though not always), as does the 18-55mm EF-S lens supplied with the Canon 350D. It looks like the Sigma 10-20mm does not, and if anyone knows whether the Canon 24-105mm suffers from an IR hotspot, I'd like to hear about it. If it doesn't, I might just buy the 77mm R72 filter too.

infrared,ireland, irishblogs,photoblogs,monasette,galway.

Posted by Monasette at May 21, 2006 07:39 PM