Improving image quality with a DSLR
// March 4th, 2009 // Photography
Carrying around a hefty digital SLR seems like overkill to most; fully decked out with a decent low-light telephoto lens and flash, my camera weighs in somewhere around three and a half kilos. That’s a lot of weight to be carrying around your neck, so why do I do it? After all, why use this?
Nikon D700 (12 megapixel)
When you can use this?
Canon Ixus 980 (~15 megapixel)
The Ixus 980 has roughly 3 more megapixels and is significantly lighter (160g vs. ~3.5 kilos), so that makes it a better camera, right?
As with most things in life, there’s no such thing as a free lunch – yes, the Ixus is lighter, but there’s a world of difference in what’s inside. To understand why, we need to take a step back and understand how a camera works. At its most basic, a digital camera has three elements – a lens, which lets light into the camera, a sensor, which captures the light, and a viewfinder, which lets you see what the camera is seeing.
Your standard point and shoot replaces the viewfinder with an LCD attached to the sensor; the sensor is then left permanently on and the camera transmits what the sensor ‘sees’ to the LCD, giving you a live view of the action. Most digital SLRs are slightly different in that they use a relatively simple mirror / prism system to reflect the light through a viewfinder; the sensor is only activated when a photo is taken. The rest of the time, the sensor is hidden by the mirror.
Logically then, there’s really only two things which affect how well the camera can capture what it’s being focused on – the lens and the sensor. Lenses are a topic in their own right, so I’ll skip over them for the moment. Suffice to say that while most people tend to focus on the body of the camera, your average SLR photographer has probably spent on lenses anywhere up to ten times what they spent on their camera body. Sound insane? Well, yeah, it kind of is, but there’s good reasons for it too.
Sensors, on the other hand, are where the first major difference lies between your standard point and shoot cameras and your average digital SLR. It’s pretty simple – as a general rule, the larger the sensor, the more light it can capture, which in turn means that for a given number of pixels, the better the overall quality of those pixels. Despite what may seem logical, not all pixels are of equal worth. Without getting too complex, every pixel has a certain amount of ‘error’ around what it shows compared against what’s in front of you; this error shows up as variation in colour (chroma) or brightness (luma). The better the sensor, the smaller the average error. And, the bigger the sensor for a given number of pixels, the easier it is to control the error (as each pixel has more information to draw from). The greater the average error, the noiser the image becomes and the blurrier hard lines in the image get.
How much of a difference can there be, I hear you ask? Check this out (taken from Wikipedia):
Camera sensor sizes
My main camera uses a full “frame sensor”, shown in the top left. Your average point and shoot uses one of the sensors in the bottom row. Your typical entry-level to mid-range digital SLR uses the APS-C sized sensors. When you consider that at a minimum, your average digital SLR is using a sensor six twelve times bigger to achieve the same number of megapixels, there’s a reason SLRs tend to take clearer images, even when using a relatively cheap kit lens.
Is it worth the extra weight and bulk? Sure it is, at least if you want to ensure you’re getting the best image possible. Entry-level SLRs like the Nikon D60 and Canon 1000D aren’t even that big or heavy, relatively speaking. They won’t fit in your pocket, but they also don’t weight over a kilo when kitted out with a general walkabout lens either.
Having said that, the camera is the least important part of the picture; a good photographer is a good photographer, and good composition is good composition irrespective of the tool used. People have even managed to take some amazing photos using nothing more than a cellphone …