> I thought that CMOS image arrays had come along enough to beat CCD by
>> now. Not the case?
>
> Dunno -- the "as of five years ago" qualifier was because that's the last
> time I paid any attention to the issue.
Don't know about video, but Canon high-end still cameras (DSLRs) went with CMOS a few years ago, and Nikon is now following suit, I think.
There's a good paper on this at
CMOS beats out CCD if the chip exceeds four or five acres in size. Especially with enough sneaky tricks.
CANON?S FULL-FRAME CMOS SENSORS: THE FINEST TOOLS FOR DIGITAL PHOTOGRAPHY search under "CMOS SENSORS"
Right... a familiar document. See also:
"mc" hath wroth:
Look again. My new Canon S5-IS camera has a CCD imager.
I dunno if this is an indication that Canon is giving up on CMOS and going back to CCD. Considering that CCD burns more power and is more expensive than CMOS, there has to be a good reason for Canon to go back to CCD.
Curious. I think it's probably connected with the small size of the sensor in that camera. Canon DSLRs (with sensors at least 2/3 the size of a 35-mm film frame) are all CMOS as far as I can determine.
"mc" hath wroth:
Good point. The CCD sensors are smaller, which allow for smaller lenses, which are cheaper. The S5-IS also does not have a removable lens. There's some obvious product differentiation between the Canon S5-IS and the EOS and Dxx series of high end cameras. One would think that since they've obvious already have the parts and technology to make CMOS work, there would be no reason to revert to CCD. Yet, their latest camera, the S5-IS, is CCD, not CMOS. As I mumbled, I don't know the significance of this change.
I was just told recently by a friend that is in this field and also showed me an article on some problems with noise in the higher end camera's. Because the customers want more mega pixels they gave it to us how ever, this has proved to be an issue now since these higher resolution units are generating noise and the article that was showed to me states that lower resolution units are producing better images.
I guess it has something to do with the spacing. 2 images were in the article and I could see the difference.
Does that have anything to do with it? I don't know.
Noise has to do with pixel size; make the pixels too small, and you're capturing too few electrons per pixel, and any slight difference will be visible. If you want multiple megapixels in a sensor less than a centimeter across, you face a challenge that is not faced by DSLRs with their near-film-sized sensors.
At the same time, larger pixels require more light, increasing the size and expense of the lenses. I find that most digital cameras are already too slow.
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