SINGLE SHOT
At Single Shot setting (AF S), the shutter release will be blocked until the camera finds the optimum focus setting. This ensures that no captures can be made that are not finely focused. However, this delay will normally be only a fraction of a second in good lighting conditions with a clear focusing pattern.
Note though that in this mode the lens will focus at a distance and will remain fo- cused at that distance while pressure remains on the shutter release button. In this way, you can focus on a nearby object for example, temporarily positioned within the focusing zone on the viewing screen and then without releasing pressure on the shutter release button, recompose knowing that the focus remains on the object cho- sen even though it is now outside the focusing zone. Releasing the pressure on the shutter release button and pressing again half way would now change the focus set- ting to the distance of the object within the focusing zone.
See Manual override in autofocus mode for a useful way of working with manual and autofocus settings in a combined manner.
CONTINUOUS
At Continuous setting (AF C), the shutter can be released rapidly before the lens is focused in order to capture a
One method to exploit this feature when photographing in a rapidly changing situa- tion is to keep the shutter release button pressed down. In this way the lens focuses constantly (according to the focusing zone) and by momentarily releasing the pres- sure on the shutter release and then immediately pressing again, you minimize the amount of time needed for the lens to check focus, thus ensuring a
TRUE FOCUS
The True Focus setting (AF T) is generally used in specific circumstances to automatically correct for camera angle/fo- cus setting discrepancies but it can also be combined with other autofocus settings.
To be able to exploit True Focus correctly, a few impor- tant points should be studied in order to obtain a full un- derstanding of how and when to use it. Basically, there are four variables to pay attention to listed below: (a) proxim- ity of camera to subject, (b) focal length of lens, (c) aperture setting and (d) movement of camera and/or subject after setting. The closer you remain to the ideal situation with regard to these variables, the more noticeable the effect of True Focus will be.
•The closer you are to the subject, the worse the original problem becomes. Consequently, the need for True Fo- cus solution becomes greater and its application thereby becomes more noticeable.
•Short focal length
•Smaller apertures increase the depth of field and there- fore would lessen the need for a True Focus solution. However, smaller apertures produce a different visual ef- fect, so True Focus therefore allows the exploitation of
the shallow depth of field (produced by larger apertures) without the fear of unwanted focus re- strictions.
•The calculations in-
volved in True Focus use, amongst other things, camera to subject distances to calculate the required amount of adjustment. It therefore follows that if the camera or the subject move after the initial setting has been made, the calculations will not be applicable anymore. So, to ensure the optimum correction, both the photographer and the subject should restrict movement as much as possible. Please note that with some lenses (particularly longer length lenses) just a few centimeters movement can essen- tially ruin the result.
True Focus can be used with longer lenses, smaller apertures etc but the further you come from situations similar to the ‘ideal’ as described above, the less the effect will be until it has no visible effect at all. Please remember that although True Focus can noticeably improve a demanding shoot it will only work effectively in the specific circumstances it was de- signed for.
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