Canon PowerShot G2 Service Manual page 10

l Digital zoom function with continuously changing angle of view (approximately 11x when used
in combination with the optical zoom)
Similar to the IXY DIGITAL 300/200 and the PowerShot A20/A10, the PowerShot G2 is equipped with a
digital zoom feature. When using digital zoom, the lens moves all of the way to the telephoto end, the camera
then enters the digital zoom range, in which the lens remains as it is but the CCD's reading area is slowly
reduced towards the center. This produces an effect that is equivalent to zooming. Unlike the digital teleconverter
mode that was used in the PowerShot G1, this method does not produce a sudden sharp drop in image quality
(see Fig. 2-3), and permits zooming up to a maximum of approximately 11x (362mm:35mm film equivalent).
In addition, because it is essential that the image zoom in smoothly on the LCD monitor when using the digital
zoom feature, there are several dozen image fetch positions between 102mm through 362mm (35mm film
equivalent) for the monitor display. In light of practical considerations, there are six positions, including both
end positions, at which zooming can actually stop.
Performing this type of processing within the camera requires time to resize the image for display, etc.
Therefore, one disadvantage is that the zoom operation becomes slower after the transition is made from the
optical zoom region to the digital zoom region. In the PowerShot G2, however, the functions provided by the
new imaging engine allow digital zoom and optical zoom to be performed at equivalent zoom speeds, so that
there is no difference that is noticeable in actual use.
Fig. 2-3 Relation between Digital zoom and imade Quality
l AE lock/FE lock (The combination of shutter speed and numeric aperture can be changed after
AE is locked.)
The PowerShot G2 permits AE lock/FE lock in the same manner as in the PowerShot G1. Furthermore, in the
program, shutter speed-priority, and aperture-priority modes, once AE has been locked, the combination of
shutter speed and numeric aperture can be changed while retaining the same EV value*.
This capability provides the photographer with the means to freely control the depth of field and feelings of
motion.
* EV = TV + AV
Magnification
(35mm film equivalent)
(Optical×Digital ）
3 x （ Telephoto end ）
Capturing images with several positions for display
4.3x
Capturing images with several positions for display
5.3 x
Capturing images with several positions for display
6.7 x
Capturing images with several positions for display
8.2 x
Capturing images with several positions for display
11x
Table 2-5 Focal length and capturing pixels
of digital zoom
1-9
Focal length
Capturing pixels
102 mm 2272 x 1704
145mm 1600 x 1200
181mm 1280 x 960
226 mm 1024 x 768
279 mm 832 x 624
362 mm 640 x 480