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Old Oct 13, 2002, 3:51 PM   #1
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Default A newbie question about ISO

I recently brought a Canon A40 and have been very pleased with the results I am getting.

I'm not a photo/camera expert and in my 35mm film camera I used standard ISO100, 200 or 400 film. I noticed that the A40 uses a default ISO of 50 and I was wondering if anyone could tell me how my camera can still produce such good results at this setting. I always thought that ISO 100 was only suitable for sunny conditions and ISO 200 was for cloudy/indoor shooting. However, my digital camera seems to take good indoor and outdoor pictures with the default ISO of 50.

Thanks in advance for any info on this!
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Old Oct 13, 2002, 4:28 PM   #2
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Hi ya

Probably the default is auto iso. This can vary between 50-150.

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Old Oct 16, 2002, 1:11 AM   #3
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There are actually two major factors which determine image quality under particular lighting conditions: ISO setting and speed of lens.

Most of the currently available consumer digicams have reasonably fast lenses. As with film, when using higher ISO settings, better light sensitivity is achieved, but also there will be more digital "noise" - the digital equivalent of film "grain."

Unlike with film where higher ISO or ASA ratings are achieved by greater sensitivity of the film to exposure, digicams amplify the captured signal. As the amplification factors rise (higher ISO's) the signal to noise ratios are such that signal is compromised and noise becomes much more apparent.

Your consumer digicam will work best if you can provide sufficient light to use the lowest available ISO setting. Most cameras with ISO 50 will produce very good images under these conditions.

Best regards,

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