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Photography Question 
Steven Chaitoff
BetterPhoto Member Since: 6/22/2004
 

CMOS/CCD Latitude


Hey, I'm wondering what kind of latitude a typical CMOS sensor has to offer. Is it more like film or slides or something in between. How about CCD sensors?

On a semi-related note, I read that CMOS sensors are absolute garbage because all the transistors in the chip make it kinda un-sensitive to light. So why do the high end Canon SLRs (& maybe others) use CMOS over CCDs?

-Steven
-http://www.vinrock.i8.com/photos/


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7/14/2004 11:39:47 AM

 
Jon Close
BetterPhoto Member Since: 5/18/2000
  You are correct to be skeptical and note Canon's success. The comment you read about CMOS being "garbage" is complete and utter nonsense. The person making it probably relied on this source, which notes some theoretical advantages/disadvantages of CCD v. CMOS. The information is at least 2 chip generations old and no longer accurate. This link, from the D30's introduction in 4 years ago, notes that Canon had overcome these theoretical difficulties. They are no longer a practical concern.


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7/14/2004 1:14:30 PM

 
John A. Lind
BetterPhoto Member Since: 9/27/2001
  Q: Why CMOS vs CCD?
A: $$$$$$$$$$$$$$$

Aside from the issue Jon mentions, CCD IC's are a different type of IC than CMOS, the substrate and materials for which are used in millions of other types of [CMOS] IC's. The IC Fab (plant that makes them) for a CCD is different from an IC Fab that makes CMOS type devices. Making CMOS sensors for digital cameras instead of CCD sensors allows leveraging on the same IC Fab (or at least portions of it) that makes many other types of CMOS IC's and it is less expensive. I'm not an expert in the exact processes and materials; there may be other cost drivers as well.

Bottom line when the analyses are done: CMOS sensors are less expensive . . . or you could bet your bippy they'd be using CCD's . . . even if the difference was only half a cent per IC. If you were heavily rewarded monetarily (bonuses) for increasing profit and could save 1/2-cent on 3 million units of production that would go straight to the "bottom line" [profit] on the corporate balance sheet, what would your decision be? I work with this type of corporate decision-making daily and *know* what the answer is, without any question.

-- John Lind


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7/14/2004 5:04:18 PM

 
John A. Lind
BetterPhoto Member Since: 9/27/2001
  Ooops . . . forgot about the latitude part of the question . . .

IIRC it's somewhere between negative and transparency . . . but there is also latitude variation with among the various negative films. I do know that negative films, in general, have less trouble with capturing highlight detail, particularly the very wide latitude professional color negative films designed for wedding/portraiture. There has been considerable discussion about this among portrait and wedding photographers.

-- John Lind


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7/14/2004 5:11:51 PM

 
Steven Chaitoff
BetterPhoto Member Since: 6/22/2004
  Thanks for all that xtra info...I understand that CMOS production enjoys economies of scale since much RAM and microprocessor production involves the same CMOS process, plants and equipment. It's just hard to imagine a company as reputable as Canon using significanty "lower tier" sensors just to save on costs. But now I know that after working through some obstacles, that is not the case with CMOS sensors. Those articles were very helpful.

Thanks again


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7/14/2004 5:53:17 PM

 
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