Dave Stevenson
Is it time to buck the worrying trend of thinking that the more megapixels you can cram onto a sensor the better the photographs will be?
There are several factors to consider when buying a digital camera. Ask me what they are and, variously, I’ll describe the importance of low-light performance, a proper manual mode and a decent selection of lenses to name a few. And, up until last month, I’d have stressed the importance of ignoring every manufacturer’s headline specification – the megapixel count.
Nonsense, I’d tell you. Megapixels counts have been climbing for years, and while resolution creeps up a few per cent with each new model, the image quality is largely left untouched. Indeed, there’s a ferocious cadre of Canon users who swear that image quality on high-res cameras such as the 7D is actually decreasing: in general terms, more pixels means more noise.
Then, while researching a feature about photo printing for MacUser’s sister title, PC Pro, I visited theprintspace, a nifty bespoke print shop in Shoreditch. Having counselled people for years not to pay attention to megapixel counts, I expected a similar answer when I asked David Moy, theprintspace’s production director, whether he ever saw images that were too low resolution to print at large sizes. Astonishingly, he said he saw a couple per week. Partly, this is because theprintspace is capable of churning out some breathtakingly large prints – for around £250, you can have an 80 x 60in giclée print made up – that’s over six feet wide.
However, the other, more interesting part is the significant difference between sensor resolution and the ability of your camera to resolve actual, real-world detail. The two aren’t necessarily related. For instance, take a picture with an old camera – take my dusty, 8-megapixel Canon 350D – and compare it with the 18-megapixel output of a 7D, which has twice the resolution. Using the same lens, the 7D takes a larger picture, but not necessarily one that gives you a sharper, more detailed image. All you can do with it is print it at a larger size, and even then other factors – such as lens sharpness, focus and exposure – all come heavily into play.
Instead, the problem with consumer-grade lenses is that they contain imperfections. These vary by lens – kit lenses tend to be soft and prone to turning high-contrast edges purple as light is refracted by imperfect glass. And while you might not see chromatic aberration or softness when you’re looking at an image onscreen, by the time you’ve created and lovingly crafted a 16 x 12in print, those technical imperfections will be shown up.
From experience, I can tell you that printing beyond the technical capabilities of your camera’s sensor is more than possible – Adobe Lightroom and Photoshop both make competent jobs of increasing the resolution of images, so you can print large images at 300dpi. Printing beyond the technical capabilities of your lens is a different matter: there’s only so much you can do to a soft image to shore it up, and while Lightroom’s chromatic aberration tool is very good, it isn’t magical. Images that aren’t perfectly sharp will look fine onscreen, but indifferent at small print sizes and distinctly ropey by the time you hit frame-able sizes – A4 and bigger.
The battle between camera resolution and lens resolution is one that lots of people are fighting with. One such war was fought in public earlier this year by the organisers of the prestigious Veolia Environnement Wildlife Photographer of the Year competition, which unexpectedly introduced a new technical rule disqualifying images from cameras with sensors with fewer than 10 megapixels. That meant, in theory, you could enter the competition with an image taken from an expensive compact camera, but not from, say, a Canon 1D MkII with a £5000 lens screwed into the front. Saying which would produce a better-quality image is pretty simple. Photographers I spoke to at the time reacted with a mixture of horror and pragmatism. Some were shocked that their equipment, which was less than five years old and cost as much as a family hatchback, was out-dated. Others reacted with a shrug of the shoulders: the march of technology is relentless, after all.
It’s interesting to see how the big manufacturers are reacting. Canon appears to have thrown in its lot with the more-is-more crowd. Its 1D MkIV, for instance, stuffs in 16.1 megapixels on an APS-H sensor. The rumoured Canon 1Ds MkIV could push past 30 megapixels on a full-frame sensor. Canon’s lower-end cameras are equally well specified: the 5D MKII has a 21.1-megapixel sensor, and the 7D – the company’s top-end APS-C camera – has an 18-megapixel sensor.
Nikon has gone entirely the other way – indeed, if the Wildlife Photographer of the Year competition raises the bar again next year, some pros with Nikon gear will start looking nervously over their shoulders. The Nikon D3s has a 12.1-megapixel sensor, which is less than many compacts. Only Nikon’s top dog, the D3X, really pushes the boat out, with its 24.5-megapixel sensor. And yet Nikon’s fortunes are on the up – it recently grabbed Canon’s market-leader position in Japan, and professionals on Nikon’s platform aren’t exactly vocal in their criticism of the less-than leading edge resolution.
Meanwhile, resolution isn’t something I’d urge you to lose sleep over. If you’re buying a new DSLR (or, indeed, any from the past four years), your new body will stuff at least 10 million pixels onto the sensor, which is enough for any current photography competition.
Those looking to upgrade from older cameras should carefully weigh their options before opening their wallets: if you’ve got a DSLR – almost irrespective of its resolution – your money will be far better spent on the best lens you can possibly afford.
I spent a few days last month shooting in Norfolk with Canon’s 300mm f/2.8 – an extraordinarily sharp telephoto lens and still more than tolerable with a 1.4x extender attached. On a 10.1-megapixel camera, there was far more scope for cropping than there was on an 18-megapixel camera with an inferior lens.
If I was choosing a body and lens combo for big-format printing, I’d pay far closer attention to the lens than the body. It’s just a shame not everyone sees it the same way.
Dave Stevenson
