Canon PowerShot G1, Service Manual

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G8
Fig. 2-4 PowerShot G1 lens configuration.
-High-resolution zoom lens with advanced optical technologies
The PowerShot G1 is equipped with a 7 - 21mm 3X zoom lens (equivalent to 34 - 102mm in 35mm format) that is suited
for a wide range of picture-taking, from landscapes to snapshots. Also, the maximum aperture is f/2.0-2.5 which is the
largest for a digital still camera. The iris-type aperture can give excellent
background blur for portraits.
The lens consists of 8 elements in 7 groups (Fig. 2-4). Two glass-molded
aspherical elements with a high refractive index are positioned for maxi-
mum effect in correcting aberrations. Also, in conjunction with the 3.34
M pixel CCD’s fine pixel pitch (3.45 micro-millimeters), group 3 has an
cemented element to correct the chromatic aberrations (throughout the
entire focal length range) that the aspherical element is unable to correct.
As a result, high optical performance is attained with only a few lens
elements making it suitable for a retractable lens.
Also, by adjusting the CCD’s tilt, the image is focused evenly through-
out.
-Wide exposure sensitivity range
Film-based cameras enable you to freely set the film speed to suit the picture-taking condition. There is a close correlation
between the film speed and image quality. Normally, a slow-speed film results in high image quality (fine grain). High-
speed film enables faster shutter speeds (to prevent blur) and smaller apertures (for greater depth of field) to be used.
In the PowerShot G1’s Creative Zone modes, you can select the exposure sensitivity as with the film speed with film-
based cameras. You can select Auto, ISO 50, 100, 200, or 400 to suit the picture-taking condition. The ISO 50 setting has
been added for still subjects when you can use a slow shutter speed or for bright scenes when you can use a faster shutter
speed for minimal noise.
At the Auto setting, the camera selects the optimum exposure sensitivity automatically within ISO 50 to 100.
-Auto cannot be set in the Manual mode.
-High-precision white balance (5 preset white b Custom white balance)
For PowerShot G1’s high-precision white balance control, the image is divided into 100,000 blocks and white is searched
and calculate.
In addition to the usual white balance settings (daylight, overcast, tungsten, and fluorescent light), the new “flash” setting
has been added to optimize the color temperature of flash pictures. White balance is improved when flash is used. Also,
as with camcorders, the custom white balance feature enables you to set the desired standard white with a sheet of white
paper under a specific light source. The custom white balance setting is then stored in the camera. This feature is useful
when you have special lighting conditions or two or more different light sources and the Auto or preset white balance
setting cannot obtain the white balance you want. The custom white balance setting is retained by the camera even after the
camera is turned off.