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Old Jun 29, 2003, 4:35 PM   #11
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Originally Posted by Alan T
I'm enquiring whether a default of 50 is common (which would surprise me), and concerned that maybe my unusually low default setting is to compensate for noisy electronics in this otherwise excellent camera.
Depends on the camera. I know with the Oly C-7x0 Series for the last few years have been ISO100 minimum, but the new C-750 has an ISO50 (according to users, the specs on Oly's site says ISO100). Presumably with the newer CCDs they've improved light sensitivity so can get the lower number.

A note about what I just said, although the previous C-7x0 cameras you could only select ISO100 as the lowest, in its automatic mode it has been seen going as low as ISO80 (and could choose odd numbers like ISO320).
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Old Jun 29, 2003, 11:06 PM   #12
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Mike_PEAT wrote
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Presumably with the newer CCDs they've improved light sensitivity so can get the lower number.
Surely improved light sensitivity corresponds to *higher* ISO equivalent rating? Am I missing something here? :?

I thought the 'sensitivity' control, i.e., ISO rating, was a gain control in the amplification of the CCD output signal. With a shot taken at 50ASA equivalent, you get lots of photons hitting the CCD, and have to amplify only a little to get a good image. If you use less light for the same shot, (i.e., a higher ISO rating) there are fewer photons, so you have to amplify the signal more, with consequent risk of noise addition.

So I'd expect improved CCDs to offer *higher* ISO ratings, not lower.
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Old Jun 29, 2003, 11:25 PM   #13
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Originally Posted by Klaus DK
The ISO can't be compared directly to film ISO...... It's not an industry standard with digicams - as each cameras consist of different electronic and software.
But surely ISO (international standard!) only has meaning if it relates the shutter speed/aperture (number of photons) for a given shot to the device you're using.

If I point and shoot on Auto with my new Casio (default ISO50) it'll give me twice as long a shutter speed as my old Olympus (default ISO100). So by going to a next generation camera, I'm twice as likely to get camera shake, and four times more likely than I'd be with a point & shoot film camera with 200ASA film in it.

What I'm complaining about is that the Casio's *default* is 50, and if I set it higher I lose the automatic ISO setting on everything but fully automatic exposure control.
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Old Jun 30, 2003, 9:21 AM   #14
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I understand you problem. Irritating isn't it!!! :twisted:
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