CMOS x CCD sensors.

Archived from groups: rec.photo.digital.slr-systems (More info?)

Dear members:

I am interested in your opinions on the differences between CCD and CMOS
sensors for SLR digital cameras. Which one is the best ? Which provides the
best image quality, color fidelity and reproduction, greater color space or
color gamut, ... ?

Suggestions and input on both Sigma's Foveon sensor as well as that
available on Fuji's line of digital SLRs will also be relevant and
appreciated.

I am also interested in reading reviews published in either print
journals/photo magazines or online publications. Are there any reviews you
would recommend ?

Thank you in advance and best regards to all.


--
Dr. Joseph Chamberlain, D.D.S.
Oral and Maxillofacial Surgery

Archived from groups: rec.photo.digital.slr-systems (More info?)

Joseph Chamberlain, DDS wrote:

> Dear members:
>
> I am interested in your opinions on the differences between CCD and CMOS
> sensors for SLR digital cameras. Which one is the best ? Which provides the
> best image quality, color fidelity and reproduction, greater color space or
> color gamut, ... ?

I doubt there is any real difference in these respects worth discussion
beyond hair splitting. And then of course the processing between the
sensor and the image output (whether in camera or in RAW import)
adds/subtracts its own flavours.

On long exposures CMOS has an advantage of using less current, so
draining the battery less and heating up the sensor less resulting in
less noise than a CCD sensor. If you don't do a lot of low light or
night photography, then this is not an important point.

> Suggestions and input on both Sigma's Foveon sensor as well as that
> available on Fuji's line of digital SLRs will also be relevant and
> appreciated.

Foveon seems to be a dead horse at present. It's not bad, but has
lagged in the all important pixel race. It's only available (AFAIK) on
the Sigma SD9 and SD10 which are very ordinary DSLR's that only work
with Sigma's lenses. Not a good option in any respect. If you make 5x7
or even 8x10 prints, it's adequate. Some people do not like the
skintones from it.

Fuji's S2 and S3 employ a novel sensor approach with an extended dynamic
range into the highlights. The cameras emply an F80 based body and
mount Nikon lenses. So it's a very good alternative.

> I am also interested in reading reviews published in either print
> journals/photo magazines or online publications. Are there any reviews you
> would recommend ?

www.dpreview.com has fairly exhaustive coverage and image samples.
(Both "real" images at full size that you can DL as well as specific
technical tests and images). You can compare the specs in a "side by
side" mode by selecting 2 to 4 cameras of interest.

Chasseur D'Images has recently gone on a test rampage testing bodies and
lenses and publishing reports in the magazine. French and possibly
difficult to get where you are, though an international newsstand may
carry it.

Cheers,
Alan

--
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-- e-meil: Remove FreeLunch.

Archived from groups: rec.photo.digital.slr-systems (More info?)

Joseph Chamberlain, DDS wrote:

> Dear members:
>
> I am interested in your opinions on the differences between CCD and CMOS
> sensors for SLR digital cameras. Which one is the best ?

I'll agree with others that it's not so simple. Beware of old articles
from a few years back when CMOS was considered trashy and only useable
for cell phone cameras. It just depends on the individual design of the
sensor these days.


--
Paul Furman
http://www.edgehill.net/1
san francisco native plants

Archived from groups: rec.photo.digital.slr-systems (More info?)

On Sun, 19 Jun 2005 13:21:29 GMT, JPS@no.komm wrote:

>In message <42b47d9f$0$2022$ed2e19e4@ptn-nntp-reader04.plus.net>,
>"Craig Marston" <binaries.newsgroup@craignospammarston.com> wrote:
>
>>Another advantage of CMOS sensors is that because they are themselves
>>digital (CCDs are analogue and require A-D conversion)
>
>CMOS sensors have little binary photon/electron counters?

No they have Plank demons (quantum version of Maxwell's) with
abacuses.

*************************************************************

"People, in various places and times, have not merely thought
different things. They have thought them differently.
It is probable that their most fundamental cerebral
process have changed through time. Their deepest emotional
drives and desires may themselves have been transformed.
Significant elements of continuity cannot be understood
without a sense of the discontinuities, too."

_Historians' Fallacies_
"The fallacy of the universal man"
David Hackett Fisher

Archived from groups: rec.photo.digital.slr-systems (More info?)

<JPS@no.komm> wrote in message
news:39sab1ptlhnm6jl3l15n4ol274rjo7al8o@4ax.com...
> In message <42b47d9f$0$2022$ed2e19e4@ptn-nntp-reader04.plus.net>,
> "Craig Marston" <binaries.newsgroup@craignospammarston.com> wrote:
>
>>Another advantage of CMOS sensors is that because they are themselves
>>digital (CCDs are analogue and require A-D conversion)
>
> CMOS sensors have little binary photon/electron counters?

Something like that yes..!

Craig

Archived from groups: rec.photo.digital.slr-systems (More info?)

"Thomas T. Veldhouse" <veldy71@yahoo.com> wrote in message
news:42b70d96$0$1961$8046368a@newsreader.iphouse.net...
> Craig Marston <binaries.newsgroup@craignospammarston.com> wrote:
>>
>> "Joseph Chamberlain, DDS" <drjchamberlain@earthlink.net> wrote in message
>> news:BED90D80.DA19%drjchamberlain@earthlink.net...
>>> Dear members:
>>>
>>> I am interested in your opinions on the differences between CCD and CMOS
>>> sensors for SLR digital cameras. Which one is the best ? Which provides
>>> the
>>> best image quality, color fidelity and reproduction, greater color space
>>> or
>>> color gamut, ... ?
>>
>> <snip>
>>
>> Another advantage of CMOS sensors is that because they are themselves
>> digital (CCDs are analogue and require A-D conversion) they can be more
>> versatile. For example the Nikon D2X has a "high speed" mode whereby a
>> smaller portion of the sensor is used. This also affects the effective
>> focal
>> length of the lens. This is the only example I personally know of that
>> has
>> been put into practice though. I believe it is also possible to combine
>> sensor elements to increase sensitivity at the expense of resolution with
>> CMOS sensors...
>>
>
> CMOS sensors are no more or less digital than CCD. The only difference
> is that the analog to digital conversion happens on the wafer rather
> than off, thus shrinking the electronics and reducing the heat. One
> side effect of this may be that higher heat production will likely mean
> more noise.

So, apart from all the built-in electronics that give a digital output and
allow each element to be directly addressed like a memory chip, they're the
same. I stand corrected.

Craig.

Archived from groups: rec.photo.digital.slr-systems (More info?)

Well, speaking as an electrical engineer...it's true...the world is
analog...so any sensor has to do the A-D conversion, it just depends
when it does it

Craig Marston wrote:
> "Thomas T. Veldhouse" <veldy71@yahoo.com> wrote in message
> news:42b70d96$0$1961$8046368a@newsreader.iphouse.net...
>
>>Craig Marston <binaries.newsgroup@craignospammarston.com> wrote:
>>
>>>"Joseph Chamberlain, DDS" <drjchamberlain@earthlink.net> wrote in message
>>>news:BED90D80.DA19%drjchamberlain@earthlink.net...
>>>
>>>>Dear members:
>>>>
>>>>I am interested in your opinions on the differences between CCD and CMOS
>>>>sensors for SLR digital cameras. Which one is the best ? Which provides
>>>>the
>>>>best image quality, color fidelity and reproduction, greater color space
>>>>or
>>>>color gamut, ... ?
>>>
>>><snip>
>>>
>>>Another advantage of CMOS sensors is that because they are themselves
>>>digital (CCDs are analogue and require A-D conversion) they can be more
>>>versatile. For example the Nikon D2X has a "high speed" mode whereby a
>>>smaller portion of the sensor is used. This also affects the effective
>>>focal
>>>length of the lens. This is the only example I personally know of that
>>>has
>>>been put into practice though. I believe it is also possible to combine
>>>sensor elements to increase sensitivity at the expense of resolution with
>>>CMOS sensors...
>>>
>>
>>CMOS sensors are no more or less digital than CCD. The only difference
>>is that the analog to digital conversion happens on the wafer rather
>>than off, thus shrinking the electronics and reducing the heat. One
>>side effect of this may be that higher heat production will likely mean
>>more noise.
>
>
> So, apart from all the built-in electronics that give a digital output and
> allow each element to be directly addressed like a memory chip, they're the
> same. I stand corrected.
>
> Craig.
>
>

Archived from groups: rec.photo.digital.slr-systems (More info?)

In article <42b73318$0$41926$ed2619ec@ptn-nntp-reader03.plus.net>,
Craig Marston <binaries.newsgroup@craignospammarston.com> wrote:
>
>"Nicholas Wittebol" <nicholas.wittebol@rogers.com> wrote in message
>news:BtednZYkD6vysyrfRVn-sg@rogers.com...
>> Well, speaking as an electrical engineer...it's true...the world is
>> analog...so any sensor has to do the A-D conversion, it just depends when
>> it does it
>>
>Don't the CMOS sensors have all the necessary "gubbins" built-in around the
>elements/light sensors/photon detectors to convert the analogue values of
>light intensity to a numerical value? Because that was one of the
>disadvantages; that the photons often hit the "gubbins" instead of the
>actual detectors.

An A/D converter takes a *lot* of transistors and resistors, so
they occupy a lot more space than the detector. As a result, they are
at best mounted at the edges of the sensor chip -- or on adjacent chips.

>If they aren't A/D converters, what are they then?

The addressing circuitry, which allows the electronics in the
camera to select one pixel at a time to feed to the A/D converter, and
then read into the camera's buffer, and from there to the media. CMOS
needs to turn on gates to feed each pixel to an output bus. CCD can
switch the pixel information along a bucket-brigade until it reaches the
edge where it is fed to an A/D. For a really *slow* system, these row
bucket brigades can feed into a column one, and feed it all out through
a single output A/D converter.

Note that since the A/D conversion takes a certain number of
cycles of the electronics, what probably is done is that there are a
bank of A-D converters along one edge -- perhaps 1/4 the number of
pixels in that dimension -- and 1/4 of the pixels in a given row are fed
to the A/D converters which start converting. As each one is complete,
it is read out, and another pixel is fed into the A/D for conversion.
The more A/D converters (probably up to a maximum of enough A/D
converters to handle a full row of pixels at a gulp), the quicker the
entire image can be read off the sensor and it can be clear for the next
shot.

Note that a lot of this is based on my old memories of Infrared
sensors in their early developmental phase, so there may be details
which I don't know -- but most of what I have said should be generic
enough to still be applicable.

Enjoy,
DoN.
--
Email: <dnichols@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Archived from groups: rec.photo.digital.slr-systems (More info?)

<snip>
>
> Note that a lot of this is based on my old memories of Infrared
> sensors in their early developmental phase, so there may be details
> which I don't know -- but most of what I have said should be generic
> enough to still be applicable.
>
> Enjoy,
> DoN.
> --
> Email: <dnichols@d-and-d.com> | Voice (all times): (703) 938-4564
> (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
> --- Black Holes are where God is dividing by zero ---

Aaah! So it's mostly transistory things mingled in next to the photosites
then..?

Cheers for your comprehensive explanation DoN! From what I had read or
misread (photographer and musician, not an engineer!) I understood that the
A/D conversion took place *within* the chip, and not at the edge like with
CCDs.

Best regards,

Craig.