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Old Apr 26, 2009, 12:09 PM   #1
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What is the difference between digital & optical zoom? Should I always have the digital zoom on on my point & shoot camera? I don't know what difference it makes whether I have it on or off. The camera has a 6X optical zoom. Also I was trying to compare the focal lengths on my point & shoot with my SLR camera. When I shot a photo with no zoom it showed a focal length of 5.8 & when I zoomed to the maximum it showed 34.8 . So would the maximum zoom on my point & shoot only be equal to a 34.8 on my SLR as I thought that was more of a wide angle length?
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Old Apr 26, 2009, 12:29 PM   #2
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What camera model? You're probably looking at the actual focal length versus the 35mm equivalent focal length.

See my post in this thread for more information:

http://forums.steves-digicams.com/fo...amp;forum_id=2

As for digital zoom, I always leave it turned off so that I don't use it by accident.

If you use a 2x digital zoom, you only have 1/4 (not just 1/2) the original pixels captured by the camera's sensor. The camera is just cropping the image (removing the outside edges) to simulate more optical zoom. Some cameras both crop and and interpolate the image (adding pixels that were not captured by the camera's sensor based on adjacent pixels), then enlarge the image back to the original size. That can degrade image quality.

If you want your subject to fill a greater portion of the frame, move closer or use more optical zoom.
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Old Apr 26, 2009, 12:32 PM   #3
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The camera is a Canon Power Shot A 700.
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Old Apr 26, 2009, 12:40 PM   #4
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The actual focal range of the lens on your Canon is 5.6-34.8mm. But, you'll have the same angle of view (apparent magnification) as you'd have using a 35-210mm lens on a 35mm camera.

The larger the sensor or film size, the wider the angle of view will be for a given focal length lens. The smaller the the sensor or film size, the narrower the angle of view will be for a given focal length lens. Your Canon has a very tiny sensor.

Point and shoot models like your Canon usually include the "35mm equivalent" focal range in their specifications, so you can see how angle of view compares to zoom lenses used on a 35mm camera. But, because of their tiny imaging sensors, the actual focal length of a lens used on a point and shoot models is very short.
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