Camera Ratings - Part 3

2006.03.17

Why is a camera rated higher than another? Because it is better, of course. What could make it better is the topic of this post. I say could because some qualities have different values to different people.

Obviously, the purpose of a camera is to take pictures. Some cameras perform other tasks such as recording movies, recording sounds, displaying a clock, playing MP3 files, printing and even playing video games. Therefore, a camera must be judged for its ability to take pictures. Ideally, the non-picture tasks should not be considered in a camera's rating. If they were, then a digital camera's rating would not be representative of its picture taking ability alone and we could not use a rating to determine which camera is better at taking pictures. This would greatly diminish its usefulness.

There are several aspects to a camera's ability to take pictures. The most commonly discussed is photo-quality. Other aspects are speed, ergonomics and flexibility. All these aspects together determine how a camera performs as a tool to take pictures.

Rightfully so, photo quality is the most important. Color, sharpness, noise, aberrations, distortion, exposure, vignetting, dynamic-range, contrast, etc. together describe photo quality. The importance of these is directly proportional to people's ability to notice them under normal viewing conditions. Under a microscope, no picture is perfect. However, normal viewing conditions do not generally involve a microscope, or 400% magnification. Normal viewing conditions are prints of various size (viewed from a distance where the entire image can be seen) and digital displays showing the entire image at once (zoom-to-fit or fit-to-fill). Only photo-quality defects noticeable under these conditions are worth considering while rating a camera's photo-quality.

The most talked about image quality defect is noise, but just like other picture-quality attributes, it only matters when it can be noticed under normal conditions. If a 3 megapixel camera image shows noise when printed at 13"x19", it doesn't matter. After all, such print sizes are beyond the resolution of a 3 megapixel camera. That is why looking at images zoomed to 100% or more on a computer screen is not so important when rating a camera.

Speed of operation includes several factors such as focus-speed, shot-to-shot speed, startup speed and image review speed. These are all very important to consider when rating a camera because they influence a photographer's ability to capture a precise moment. If a camera focuses slowly, then pictures of moving objects will likely be problematic. If a camera starts-up slowly, then candid photography will be harder.

Since ergonomics influence the ability to capture precise moments, they are very important. Ergonomics include the handling of a camera and its ease-of-use in terms of buttons, menus, viewfinder, displays, etc. We include the menu-system in ergonomics, which some sites may separate as user-interface, since it seems to fit the Webster definition.

A camera's flexibility includes all its photography-related features such as available lenses, connectivity to flash systems, exposure modes, ISO sensitivity range, shutter-speeds, white-balance options and image parameters among many other things. These features all affect what is achievable with a digital camera.

The 3 aspects just discussed are the most important ones to consider when rating a camera, since together they determine what is achievable with a particular digital camera. There are several secondary aspects which can influence a camera's rating but the bulk of a rating should come from these 3 aspects.

Secondary aspects to consider include durability, batteries, memory and LCD resolution. These aspect have a smaller effect on a camera's potential to take great pictures since there are ways to work-around them. For example, xD cards may be more expensive and not available in large capacities but these limitations are not insurmountable.

So what is there not to consider? First, price. Price affects a camera's value but it should not affect its rating, that way people can judge with their own budget how good a camera they can afford. Also prices regularly fall and can vary greatly by geographic location. Other aspects not to consider: connection speed, included memory card, non-photographic features. All this don't restrict the ability to take quality pictures, so why consider them for a rating?

A digital camera rating which follows these guidelines will relate a camera to its quality as a picture-taking tool, which will satisfy the purpose of rating camera in the first place. Subjectively speaking a site can base its rating scale on the relative performance of all cameras or only of cameras in the same class. Neocamera does the latter for non-competing categories such as small cameras and DSLR cameras, but that is up to the site. This is useful because it allows the rating scale to be filled by cameras in almost any class. One current exception is the SLR class which does not have any models rated poor.

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