4. Recap On Balance, Modes, Etc

White balance: Made up of blue, green and red, sunlight is the ultimate reference for white light. Depending on the light conditions, the white can be slightly different from the reference (dusk, indoors, cloudy skies, for instance). The eye automatically corrects the discrepancy, but a camera is more objective. It reproduces the difference in value and this can be the source of some surprises. Hence the idea of "white balance," a function which rebalances the light. Its purpose is to render a white that is very close to the reference value. All cameras have an "automatic white balance" position. Most of them also have more precise presets like "indoors," cloudy" or "fluorescent" (for the ubiquitous strip lighting in offices) to further enhance the result when the automatic function is inadequate. On some models, there is even a manual position which comes into play when you place a white surface (like a sheet of paper) in front of the camera so that it will automatically adjust its values. This will give you a consistent image.

Result modes: Result programs are increasingly common. They are presets adapted to specific situations - sunset, portrait, sport, landscape and so forth - and set the focus parameters according to the subject so that the picture is better and the shot easier to take. You will find the results vary with different cameras.

P, A, S, M modes: Less common, but a necessity for experienced amateurs, the P, A, S and M modes are for those who want to take matters further. P (Program) is automatic and you have nothing particular to do. A is for Aperture - you select the one you want and the camera does the rest, as it does with S (Speed), where you choose the shutter speed. With M (Manual), you choose both the aperture and the shutter speed to obtain the exposure you want. As the word implies, this setting allows you to apply your own rules.

35 mm equivalent: Focal distances are given in "35 mm equivalent." This is because the market is used to thinking in terms of the 24 x 36 mm image format of the vast majority of conventional cameras. CCD sensors are smaller than 24 x 36 mm, so the focal distance is not the same (the angle relates to the diagonal of the lit surface). 35 mm in 24 x 36 can translate to 7 mm with, say, a 1/1.8" CCD sensor, and vice versa. To simplify and standardize the principles of wide-angle, telephoto lenses, etc., the focal distances of digital cameras are converted into 24 x 36. What is really 7-23 mm can be cited in the camera specs as 35-115 mm in 24 x 36. There is of course no relation, but as the enlargement factor is the same, the conversion is neither random nor unintelligent. It works out easier in the end and keeps everyone happy.