INFRARED ON THE CHEAP

We've all seen the articles stating that you can get otherworldly infrared effects by having a little irreversible surgery done to your DSLR sensor. Without a special filter that's mounted in front of the camera's CMOS sensor, infrared light would normally spoil your images. So, in order to invite infrared light in, the filter needs to be removed. Not willing to dedicate a DSLR to infrared-only, I looked for other ways to easily get on the infrared bandwagon.

As I still occasionally shoot with medium format black and white film, the obvious thing for me was to get some infrared-sensitive film and a recommended filter. This filter is a deep red filter that favours light with wavelengths of 720 nanometers or longer. If this is sounding too techie and out of your league - hang in there - I have a simple digital solution.

By taking that same filter and holding it in front of my CCD sensor-based point and shoot camera, I was astounded at how well the infrared effect came through. Now, in colour, the image does look ethereal, but predominantly red. My preference is to either switch the camera to monochrome before taking the shot, or convert to black and white after in software. After shooting the same scenes using this technique and then using the film camera with the same filter, the results are surprisingly similar.

The reason that the CCD sensor works is that it doesn't have the infrared-removing filter that's built onto CMOS sensors. So, by using a deep red filter in front of a CCD camera lens, you are filtering out much of the visible light and letting mainly infrared light hit the sensor. Using the filter in front of my CMOS-based DSLR camera, however, I verified that the infrared effect is not really achievable.

What about using smartphone cameras with this method? Unfortunately, the newer phones seem to be equipped with CMOS sensors, so they're generally not a good candidate.

You may be wondering by now what this "infrared effect" is that I've been blathering on about. Simply, if you take picture through a deep red filter onto either infrared film or a CCD sensor on a sunny day, the vegetation (leaves, grass) will appear white or pale. It gives the impression that frost or snow has settled on the trees and lawn. At the same time, the sky appears dark, giving a dramatic contrasty scene.

Have a look at the two images in this post, both shot in summer with my point and shoot camera and the deep red filter. Have a tripod handy, though. The filter gives 5-6 stops of attenuation, meaning exposures are going to be very long.

Size matters – in sensors, that is.

When digital SLRs started to come into the market, they essentially replaced the 35mm film camera. In most cases, the lenses that fit your 35mm camera could now be used on the new digitals (from the same manufacturer, of course) without the need for any adapters. Sweet.

Those who made this transition noticed something right away. The 50mm focal length lens that gave a ‘normal’ angle of view on their film camera now acted like an 80mm lens, or slight telephoto, when attached to the digital SLR. In other words, the image was now magnified compared to using the same lens on the 35mm camera.

In some ways this was a benefit, because it meant that the telephoto lens you bought for your 35mm camera now reached a bit further on the digital SLR– about 1.6 times further. The downside was that the wide angle lens that used to work beautifully for landscapes on your 35mm wasn’t so wide anymore on the digital.

This difference is attributable to the size of the sensor in the digital camera. Most consumer SLRs use an APS-C size sensor, which is 22mm x 15mm. Compare that to 35mm film at 36mm x 24mm. Given the same lens projecting the same ‘image circle’ on the digital sensor  and the 35mm negative, the digital sensor only captures part of what the negative captures. Essentially, the digital image is magnified (by 1.6 times) since it’s like zooming in on a small part of the image circle.

For years now, professionals who could afford it have been using full frame digital SLRs (example – the Canon 5D) which use a 36mm x 24mm sensor, just like the 35mm negative size. While the manufacturers could have stuffed more pixels into this bigger sensor (and did so to an extent), the big benefit is that they can now make the pixels bigger.

Why? The bigger the pixel, the more light it can gather, meaning the camera will yield less ‘noise’ in the image in low light situations. Overall, the image is cleaner and yes, at a somewhat higher resolution. In fact, Nikon recently introduced the full frame D800 with an astonishing 36 megapixel sensor. Compare that to the Canon 5D’s 22 megapixel resolution or 18 megapixels on most consumer SLRs. Of course, file sizes bloom with higher resolution.

All of this is significant because the prices of full frame camera bodies are starting to slide below the $2000 price point. While APS-C and other similar size sensors kick-started the digital photography revolution, affordable full frames will eventually bring it full circle. The smaller sensors won’t disappear for a while yet, but those of us who came up through the film world will once again be able to shoot the way we used to – only with the immediacy of digital and a moderate size hole in our pocket.

Are Point-and-Shoot Cameras Really That Good?

As someone who shoots stock images using SLRs, it may seem strange that I find it necessary to have a digital point-and-shoot in my possession.

Not so strange when you consider that the lenses, resolution and exposure modes are starting to catch up with their big, interchangeable lens cousins. Besides, sometimes a small no-fuss camera, due to its portability, is available to capture images we would otherwise miss because we left our clunkier gear at home.

But can they really compete on image quality? I decided to pit a Canon Rebel XTi SLR against a Panasonic Lumix FX500 point-and-shoot, each claiming 10.1 megapixel resolution. I shot the same image outdoors on each camera in rapid succession, so the light was consistent. The Rebel was set to record in JPEG only (instead of RAW) so that it matched the Lumix method of recording. Each was set to aperture priority and f/8. Shutter speed was 1/40th to 1/50th for each. Both were set for auto white balance.

The fundamental difference between the two cameras, of course, is the physical size of the sensor and the technologies used. The Rebel uses a CMOS sensor, while the Lumix uses a smaller CCD sensor. To be accurate, it should be noted that the Lumix creates a 10.1 megapixel image when in 4:3 mode, while in 3:2 mode (to match the Rebel's aspect ratio)the image size is actually 9 megapixels.

Examining the zoomed-in crop of each image, it's apparent that the little CCD can't compete with the larger CMOS, both in terms of sharpness in transitions from white to red, for example, and in colour saturation in general. Also, the CCD appears "grainier" amongst the blades of grass, and falls short in latitude (or dynamic range) when compared to the Rebel image.

The results may seem obvious, given the smaller size and lower cost of the p & s. So why bother?
Well, I wanted to gauge just how far apart the quality levels were. In my opinion, while the p & s is not up to pro standard, it's still amazingly good. I'm going to use it to take test shots of scenes that I might want to return to later and shoot with the SLR. Besides, how many times have we jumped in the car and wished later that we had grabbed a camera?