Use zoom lens focusing accurately and quickly for skills

A great photograph,CANON PowerShot S45 Battery in most cases all need a clear focus. Focusing accurately is so important, people will do spend a times the price to buy have 19 points a full, the central double cross focus system 7 D, not in the 7 D with the same photographic of components of the 550 D, though in fact their quality performance and no essential difference.

The 7 D with the focus of the crazy in sports photography CANON PowerShot S200 Battery system or birds, of course there are irreplaceable field of photography, the practical. But if we face IS not very fast movement subjects, and use of IS similar EF-s 17-85 IS USM such zoom lens (I believe most of the fuselage with three digits fans are the combination it), in fact there IS a way of focusing the camera can performance to the extreme.

Any a zoom lens to zoom in only part of the time, the CANON PowerShot S400 Battery position of the focus will not be changed, and the nature of this work good lens the more precise. The technique used by the principle is that the long, sharp narrowing of the depth of field, and at the time of the system is the most precise focus work.

For example, in the following pictures with 38 mm equivalent is the focal length of the shooting, the focus is sure to fall to the eyes of buffalo. The first head of the central focus QuJingKuang as for buffalo, and then again in composition, and look is no problem, but this is not the most accurate way, because of the 38 mm focal length, the use of the largest aperture, depth of field or very wide, use the method above of focus, may be the head and the water buffalo front lawn is clear, and it is also possible that the head and the CANON PowerShot SD110 Battery water buffalo behind the lake is clear. In a word, I mean is the head of a buffalo may not in the centre of the scope of the depth of field, also is the focal place of the theory of the most vivid part, focus error range may achieve more than 1 m. This is not play in the focal length lens aperture combination largest power.