Canon PowerShot A30 Service Manual page 13

AF Frame (3-point) auto selection (AiAF) and center single-point selection (AF)
The PowerShot A40/A30 incorporates both the 3-point AiAF method in
which the camera automatically determines the proper AF frame from
three measurement points, and the standard AF method that uses a single
center point, so the user can select the best method depending on
photographic conditions.
Selectable of evaluative metering and spot metering
In the PowerShot A40/A30, a spot metering function has been added
to the averaging light metering method employed by the PowerShot
A20/A10. The averaging method divides the screen into many blocks,
allowing the camera to determine the optimum exposure setting from various complex lighting factors such as
the light exposed in each block, subject position, brightness, background and foreground lighting and reflected
light. Supplementing this method, the spot metering method measures the light only at the center of the field.
"Macro","Snap" and "Landscape" are available in the focus zone
Added to the PowerShot A40/A30 is a Snapshot mode optimized for snapping pictures of people 1.5 to 2.5
meters from the lens. This mode joins the Macro mode for close-up photography of subjects 16 cm (26 cm in
telephoto) to 76 cm from the lens, and the Distance mode for landscape photography of subjects 5 m or further
from the lens.
These distance ranges minimize the time required for the AF system to determine the correct focal distance.
16cm
Shutter speed is allowed from 15 sec. to 1/1500 sec.
The PowerShot A40/A30 provides a 15-second long-exposure shutter speed, the longest level available in this
class of camera (with shutter-speed priority). Combining this speed with the F2.8 aperture setting provides
photos with a maximum of EV 1 (ISO 100 equivalent), permitting photography in dark environments without a
strobe.
Also, with the fastest 1/1500-second shutter speed, fast-moving subjects can be photographed with minimal
blurring.
Enabling for On/Off selection of AF-assist light
Many of the PowerShot series are equipped with an assist light to ensure proper autofocus when ambient
brightness is below a certain level. However, when photographing animals in a dark environment, they may react
to the AF assist light by running away, preventing the desired photo from being taken in such situations.
The PowerShot A40/A30 therefore includes the capability to turn the AF assist light on and off, so that photos
can be taken without it in situations like the above.
*When the surrounding light level is extremely low, the AF function may be unable to determine the proper
focus. In such cases, the focus is fixed at a specific point.
1.5m
76cm
Fig. 2-2 Each focusing zone
1-8
When AF frame is selected, frame turns on to green.
Photo 2-2 3-point AiAF
2.5m 5m