Monday, July 19, 2010

One Easy Rule for Quality Images

MANY PHOTO hobbyists, if they take pictures with one of the very many consumer compact cameras, soon ask for advice on how to improve their picture quality.

Admittedly, many photo faults are hard to describe, unless you know what to look for — certainly I know that from experience. But I constantly hear complaints that photos are fuzzy and grainy.

Initially, there seems to be a belief that something is wrong — either with the photographer himself or perhaps the camera isn't working right. Well, yes, maybe. Simple problems like camera shake are easily overcome, and learning how to set the camera properly will improve image quality. But even excellent technique still ultimately gives poor quality results: the images have a certain irreducible amount of fuzz and grain. Our eager beginner realizes that the problem is with the camera, and seeks to upgrade.

Then comes the agonizing part. Should I get Canon, or Nikon, or Sony, or Olympus, or Pentax? Something else? Ought I save my money to get a Leica? Then what lenses should I get?  Is is true that prime lenses are better than zooms? Should I get a 35mm or 50mm lens? Is f/1.4 maximum aperture better than f/1.8? What are the sharpest lenses? How many megapixels should I get? Are off-brand lenses as sharp as manufacturer's brands? Which camera model should I get? Should I buy new or used? Should I wait until the new models come out? What will give me the best image quality?

Some photographers assert that the camera does not matter, that any camera, used properly, will produce good results. The important things, they claim, are composition and subject matter. This is undoubtably true — but the camera acts as an intermediary between artistic vision and the material world as photographed. The medium used has a great effect on how the viewer perceives the final artwork; the medium used can be so jarring as to even overwhelm the purported final purpose of composition and subject. We see this in Lomography, where the photographer intentionally uses poor-quality cameras and ignores camera technique to achieve a very specific low-fidelity look. But does that ‘look’ serve the higher purpose, or is it an end in itself?

(Note: much contemporary emphasis on studying the media itself rather than the content of media, is due to the pioneering studies of Marshall McLuhan; although this study is worthy in itself, in my opinion, we need to re-emphaize content while not discounting the medium. A photographer who spends too much time contemplating the meaning of photography at the expense of higher things may have images that suffer in quality.)

But consider the fact that a single fuzzy, grainy photograph of a dear loved one is of vastly greater importance — to the lover — than a gallery of even the most finely crafted art photographs. As Chesterton wrote, “if a thing is worth doing it is worth doing badly.” But some subjects, out of worthiness and justice, ought to be portrayed in a better way, although a poor image will suffice.

Inexpensive compact digital cameras have a low signal-to-noise ratio, that is, much of the image as delivered consists of artifacts that are not present in the scene photographed. We perceive this noise as fuzziness and grain. We may see a certain blocky quality of the pixels if we view the image close up: this is due to high lossy JPEG compression often found in compact cameras. Also, consider that many low-end cameras include aggressive noise reduction — this invariably results in the destruction of detail.

It is understandable that photographers would want to get rid of this extraneous noise and deliver a clearer final image, a picture that is more faithful to the subject of the photo, a picture that looks sharper and cleaner.

There is basically just one easy rule for quality photography: a bigger sensor means better quality.

Many factors go into making a quality image, but the overwhelming quality advantage goes to the larger sensor. Many problems simply fall away when the sensor size is larger. First and foremost, optical quality becomes less of a concern when the sensor is big: you just don't need that good of a lens when it delivers an image over a larger surface area. Sharpness is a given when you use a large sensor. The problem of packing too many pixels in a small area leads to the problem of noise, and a large sensor with big pixels will have very low noise.

Within the market of inexpensive consumer cameras, we see sensor sizes ranging from less than 2 square millimeters to over 360 square millimeters. We can expect image quality to be roughly proportional to surface area.

Original image source and attribution:

Good image quality is easy to find and is low in cost, as long as you are willing to use a larger camera. Any DSLR-class camera will deliver far better image quality than a typical compact camera, since they all have much larger sensors, as well as inherently better lenses and other incidentals.

Well, some photographers insist that they want to improve their image quality, but only in a compact camera. That is tough. There are some new cameras that do offer larger sensors in a compact case — but these are often at extreme cost. Good quality can be found in slightly larger, and much more economical cameras. You just have to be humble and accept the compromise of having a slightly larger camera.

By sensor I also mean film. Chemical photographic technology is nearly two centuries old, and is very highly refined. The image quality that can be delivered by a used 35mm film camera is quite impressive, and there is no comparison when you use medium or large format film. Film cameras are inexpensive, but are less convenient than digital. Large format cameras are extremely inconvenient, but also deliver unmatched results.

Film cameras are inconvenient, but can deliver superior results. We can likewise capture extreme quality images with even cheap digital cameras if are willing to be inconvenienced.  By taking multiple overlapping photos of an object — but only a static object, unfortunately — we can simulate an arbitrarily large camera sensor by fusing the images together on the computer.

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