Canon PowerShot G2 Service Manual page 11

l Evaluation metering, center-weighted averaging metering and spot metering (AF frame link/cen-
ter fixed)
In addition to the light metering modes that were available in the PowerShot G1 (center-weighted averaging
metering and spot metering), the PowerShot G2 also offers evaluation metering. The user can switch among
all of these modes.
The center-weighted averaging metering method measures light over the entire image and weights the sen-
sitivity according to proximity to the center of the image; accordingly, this light metering method emphasizes
the center of the image. With spot metering, light is measured within a specific portion of the image.
With evaluation metering, however, the entire screen is divided into blocks, and for each block the camera
evaluates many complex lighting factors based on the state of exposure of the individual block, such as the
position of the subject, the brightness, the background, and whether the subject is lit from the front or the rear.
In this way, the camera is able to derive the best exposure for each block.
Note that if spot metering is selected, it is possible to select either a "movable" or "center fixed" for the AF
frame (three points).
Note that if spot metering is selected, it is possible to select either a "movable" or "center fixed" for the AF
frame (three points).
l Continuous shooting mode, can be switched between "high speed" (2.5 images per second :
Large/Fine) and "normal" (1.5 images per second: Large/Fine).
In addition to the existing continuous shooting mode (normal)*1, the PowerShot G2 also offers the choice of
the new "high speed" mode.
When "high speed" is selected, pictures can be shot continuously at an even faster pace of 2.5 pictures per
second (when Large/Fine is selected*2); this is made possible by changing the method by which image data
is stored temporarily in the buffer. However, the total number of images that can be shot at this fast speed
(2.5 pictures per second) is approximately 5 pictures, which is fewer than is possible with the conventional
continuous shooting mode (1.5 pictures per second) which can be shot at the amount of approximately 9
pictures.
When the buffer becomes full, regardless of which mode was selected, the continuous shooting speed slows
due to the need to create space for each picture while continuing to shoot. Shooting can still continue at this
pace until the CF card becomes full.
Providing these two continuous shooting modes allows the user to select
whichever is best suited to the application at hand.
* 1 Provisional name
* 2 The speed of continuous shooting and the number of pictures thatcan be
shot at high speed varies according to the image quality mode.
l Four settings for the number of recording pixels
Since the number of CCD pixels has been increased to 3.95 million effective pixels with the PowerShot G2,
there are now four possible settings for the number of recording pixels: Large, Middle 1, Middle 2, and Small.
Since there are also three compression rates (Superfine, Fine and Normal), a total of twelve different combi-
nations (JPEG) can be selected; together with the RAW option, that means there are a total of thirteen
different image quality options.
l Histogram display of playback image
During playback, the PowerShot G2 is capable of dis-
playing a histogram of the photo image on the LCD
monitor in a manner similar to the EOS D30. The histo-
gram is a graph with the horizontal axis representing the
brightness and the vertical axis depicting the cumulative
number of pixels that have that brightness. If the bal-
ance of the pixels is distributed towards the right side of
the graph, that indicates that the image is bright.This graph
allows the user to check the distribution of brightness in
photo images, making it a tool for checkingthe overall
exposure state of the each photo.
Furthermore, if the picture includes any areas of whit-
eout, the graph flashes as a warning.
ƒŒ ƒx ƒ‹
Level
ˆÃ ‚¢
Dark
Fig 2-4 Histogram (Concept)
1-10
Recording Pixels
Large 2,272×1,704
Medium 1 1,600×1,200
Medium 2 1,024×768
Small 640×480
Table 2-6 Recording Pixels
–¾ ‚é ‚¢
Bright