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Author Topic: CCD and CMOS  (Read 24054 times)
Fine_Art
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« Reply #80 on: January 11, 2013, 05:20:52 PM »
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Hi ... can you back that up? 

Never heard that before and not sure what would account for such a difference.

Its old tech. It used to be that the CCDs were making better color uniformity. CMOS looked artificial.

Many people thought it was based on the method of charge conversion. CMOS integrated the A/D converter into the pixel. CCD sent all the charge to a row converter. The theory was the CCD method allowed calibration of the value to a standard with higher tolerance than a single value from a pixel.

The last generation of CMOS from all the DSLR manufacturers seems to have much better color accuracy than a few years ago. Pictures now look realistic, like looking through a window whereas the CMOS a few years back looks a bit artificial. Maybe its improved bayer algorithms. Maybe its the latest updates to RAW converters. Something has changed on the CMOS side.
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ErikKaffehr
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« Reply #81 on: January 12, 2013, 12:08:48 AM »
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Hi,

CMOS never integrated the ADC into a pixel. The major difference is that CMOS essentially outputs a voltage while CCDs shift the charge of each pixel to the edge of the sensor. CMOS needs a few gates to handle readout in each pixel while CCD has no electronics at all.

On older Nikons the ADC-s were off chip, they were using Burr&Brown converters in external housings. I'm pretty sure that Canon also uses off chip converters.

The most significant difference between CCD and CMOS may be that CMOS can be read out nondestructively. So, essentially all CMOS vendor use a method called correlated double sampling where they measure charge on each pixel after reset and by that method are able to eliminate much of the noise.

Best regards
Erik

Its old tech. It used to be that the CCDs were making better color uniformity. CMOS looked artificial.

Many people thought it was based on the method of charge conversion. CMOS integrated the A/D converter into the pixel. CCD sent all the charge to a row converter. The theory was the CCD method allowed calibration of the value to a standard with higher tolerance than a single value from a pixel.

The last generation of CMOS from all the DSLR manufacturers seems to have much better color accuracy than a few years ago. Pictures now look realistic, like looking through a window whereas the CMOS a few years back looks a bit artificial. Maybe its improved bayer algorithms. Maybe its the latest updates to RAW converters. Something has changed on the CMOS side.
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Fine_Art
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« Reply #82 on: January 12, 2013, 01:01:42 AM »
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We both use Sony and they have advertised on chip A/D conversion for ages.

Yes, Canon and Nikon were doing something different, maybe why they had 14 bit while we were stuck with 12. Pentax also tried high end external 22 bit converters. They went back to something basic in the next version.
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ErikKaffehr
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« Reply #83 on: January 12, 2013, 02:16:00 AM »
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Hi,

To be exact, Nikon D800/D800E, D600 and D3X use Sony Exmoor sensors using on chip converters. D3/D3S and D4 uses Nikon designed chips using external converters. Nikon D3X had both 14 bit readout (slow 2FPS) and 12 bit readout. I guess the reason Sony had 12 bit converters was more related to Bionz being a 12 bit chip. The Alpha 77 I have now has 14 bit conversion.

Pentax used Samsung chips in older cameras the K5 has an Exmoor with 14 bit readout.

DR figures from DxO (latest sensor). The DxO figures are scaled for a smallish print size. DR for actual pixels cannot exceed the channel width.

CameraDRcomments
Nikon D80014.4Exmoor based sensors
Nikon D60014.2
Sony RX114.3
PentaxK514.1Note that K5 is APS-C, impressive feat!
Sony Alpha 99 (SLT) 14
Phase One IQ18013.6Best medium format CCD based camera
Nikon D413.1Best non Exmoor design CMOS
Canon EOS 1Dx11.8
Leica M911.7Best CCD based full frame

Updated: Small corrections + added Phase One IQ180 replacing Pentax 645D as best CCD MF camera.
Best regards
Erik


We both use Sony and they have advertised on chip A/D conversion for ages.

Yes, Canon and Nikon were doing something different, maybe why they had 14 bit while we were stuck with 12. Pentax also tried high end external 22 bit converters. They went back to something basic in the next version.
« Last Edit: January 12, 2013, 08:31:34 AM by ErikKaffehr » Logged

FranciscoDisilvestro
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« Reply #84 on: January 12, 2013, 02:30:01 AM »
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DR figures from DxO (latest sensor)

CameraDRExmoor based sensors
Nikon D80014.4
Nikon D60014.2
Sony RX114.3
PentaxK514.1
Sony Alpha 99 (SLT) 14
Nikon D413.1Best non Exmoor design
Pentax 645D12.6Best CCD based camera
Canon EOS 1Dx11.8
Leica M911.7Best CCD based full frame

Best regards
Erik



Hi, Remember those figures are for the print performance (imaged resized to 8"x12" @ 300 dpi)
It is not possible to have more than 14 bit DR at the sensor with 14 bit linear encoding

The highest DR (according to DxOMark) would be thge Sony RX1 with 13.47 and Nikon D600 with 13.44

regards,
Francisco
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ErikKaffehr
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« Reply #85 on: January 12, 2013, 02:50:35 AM »
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Hi,

I remember that those values are scaled for same size but I actually feel that they are more relevant than actual pixel values, also they were much easier to find.

You are absolutely right that it is not possible to encode more than 14 EV in 14 bit linear space.

The interesting point is that all the top cameras use Sony technology. Nikon uses Toshiba for D5200 by the way. I guess Sony is not alone with on chip per column conversion. The new sensor for the Leica M is also a CMOS design with column type on chip converters.

http://www.cmosis.com/news/press_releases/new_leica_m_uses_cmosis_24_mp_cmos_image_sensor

http://www.chipworks.com/blog/technologyblog/2012/10/25/full-frame-dslr-cameras-part-iii-new-entrants-and-look-forward/

It will be interesting to compare Sony's technology with similar constructions from the competition.

Best regards
Erik


Hi, Remember those figures are for the print performance (imaged resized to 8"x12" @ 300 dpi)
It is not possible to have more than 14 bit DR at the sensor with 14 bit linear encoding

The highest DR (according to DxOMark) would be thge Sony RX1 with 13.47 and Nikon D600 with 13.44

regards,
Francisco
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jeremypayne
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« Reply #86 on: January 12, 2013, 08:21:47 AM »
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It used to be that the CCDs were making better color uniformity. CMOS looked artificial.

Previously, you stated that better "uniformity" was "still" an advantage for CCD-based sensors.

I don't think there is anything inherent in CCD technology that would account for that.
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ErikKaffehr
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« Reply #87 on: January 12, 2013, 10:13:37 AM »
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Hi,

I would suggest that there are a lot of myths in this area. CMOS is main stream. CCDs are used by small companies making high end stuff. Most CCDs are made by Kodak (R.I.P.) or Dalsa.  In general, CCDs often lack OLP filtering which is good for perceived sharpness but creates a lot of fake detail.

Kodak and Dalsa may use a different CGA (Color Grid Array) than say Nikon or Canon. So the myth goes that CCD has better color then CMOS, but that has little to do with CCD vs CMOS and a lot to do with CGA design.

Best regards
Erik




Previously, you stated that better "uniformity" was "still" an advantage for CCD-based sensors.

I don't think there is anything inherent in CCD technology that would account for that.
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Fine_Art
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« Reply #88 on: January 12, 2013, 02:17:11 PM »
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Previously, you stated that better "uniformity" was "still" an advantage for CCD-based sensors.

I don't think there is anything inherent in CCD technology that would account for that.

I believed it until I started seeing a lot of pictures from people using the Sony A99, A77 ( I use sony), the Nikon D800, D600.
Maybe its the down-sampling leeway of the 24MP of data. Maybe its improved software. I dont know. All I know is these cameras are outputting images that look very realistic vs older generation DSLRs.

The DR and the color tone accuracy are improved, from hardware or software is unknown.
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Fine_Art
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« Reply #89 on: January 12, 2013, 02:21:30 PM »
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Its not just my eyes, DxO is measuring a jump in image quality on these cameras.
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BJL
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« Reply #90 on: January 12, 2013, 03:05:02 PM »
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I guess Sony is not alone with on chip per column conversion. The new sensor for the Leica M is also a CMOS design with column type on chip converters.

http://www.cmosis.com/news/press_releases/new_leica_m_uses_cmosis_24_mp_cmos_image_sensor

http://www.chipworks.com/blog/technologyblog/2012/10/25/full-frame-dslr-cameras-part-iii-new-entrants-and-look-forward/
Panasonic is also doing column-parallel ADC in some sensors: read about the MN34070 is this document
http://www.semicon.panasonic.co.jp/en/support/catalogs/pdf/T12013CE.pdf

Chipworks has confirmed that this is the sensor in the GH2:
https://chipworks.secure.force.com/catalog/ProductDetails?sku=PAN-DMC-GH2-K_Pri-Camera
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jeremypayne
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« Reply #91 on: January 12, 2013, 04:16:42 PM »
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The DR and the color tone accuracy are improved, from hardware or software is unknown.

No doubt... But not the question at hand.

The point is ... there are not inherent characterisics of CCD technology that produce "more uniform" output relative to CMOS technology.

Any differences are due to other factors and design choices not specific to CCD vs CMOS.

As alluded to by Erik  ... This would qualify as a bit of an urban legend.
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Fine_Art
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« Reply #92 on: January 12, 2013, 04:24:36 PM »
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Its more a case of CCD tech was far more mature than CMOS tech. Now CMOS is as good or better on all parameters.
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ErikKaffehr
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« Reply #93 on: January 13, 2013, 01:09:20 AM »
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Hi,

Much of the image quality actually comes from the raw converters. For instance the new processing pipe line introduced in LR 3 was a major improvement at least for my Alpha 99, see here: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/32-new-raw-processing-pipeline-in-lightroom-3-beta-2

I have recently acquired a Sony Alpha 99. Naturally enough I shot some comparison pictures with my Alpha 900 and could see no difference at low ISO. I did shoot a horse jumping at ISO 6400 and printed A3, something I wouldn't dream of with the Alpha 900, so I'm pretty sure the Alpha 99 has a cleaner sensor (less readout noise and probably a higher FWC).

The main reason I bought the Alpha 99 is live view.

Best regards
Erik


I believed it until I started seeing a lot of pictures from people using the Sony A99, A77 ( I use sony), the Nikon D800, D600.
Maybe its the down-sampling leeway of the 24MP of data. Maybe its improved software. I dont know. All I know is these cameras are outputting images that look very realistic vs older generation DSLRs.

The DR and the color tone accuracy are improved, from hardware or software is unknown.
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Fine_Art
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« Reply #94 on: January 13, 2013, 11:08:31 AM »
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It does look like a big improvement in LR3 over past versions. I had never been impressed with the product before, maybe now it's worth a look. I still see chroma smear over the image.

The boost in fine detail contrast looks like a fine wavelet pass.
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jeremypayne
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« Reply #95 on: January 13, 2013, 12:45:29 PM »
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It does look like a big improvement in LR3 over past versions.

Lightroom is on v4.x

Lightroom is beyond impressive to me ... it the single most impressive pieces of "consumer" software I have ever seen.  The ambition and "game-changing" nature of the project is inspiring to me as someone who lives in "legacy" world trying to innovate.

The story of Lightroom is a an amazing story.
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Fine_Art
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« Reply #96 on: January 13, 2013, 01:23:16 PM »
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Lightroom is on v4.x

Lightroom is beyond impressive to me ... it the single most impressive pieces of "consumer" software I have ever seen.  The ambition and "game-changing" nature of the project is inspiring to me as someone who lives in "legacy" world trying to innovate.

The story of Lightroom is a an amazing story.

Lets not get carried away. We are not talking about a Saint here.
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jeremypayne
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« Reply #97 on: January 13, 2013, 02:14:00 PM »
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Lets not get carried away. We are not talking about a Saint here.

I stand by every word I said. 

I manage a lot of software development as part of my professional life.  One of the "catchphrases" I use often in the context of user-driven software companies and projects ... "Rather than build a little something for everyone, build everything for someone."

The Lightroom team clearly understands that principle.
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ErikKaffehr
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« Reply #98 on: January 13, 2013, 02:22:41 PM »
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Hi,

For me Lightroom was exactly the program I wanted to write, but I estimated it at 30-100 man years, longer than I plan to live.

Best regards
Erik


I stand by every word I said. 

I manage a lot of software development as part of my professional life.  One of the "catchphrases" I use often in the context of user-driven software companies and projects ... "Rather than build a little something for everyone, build everything for someone."

The Lightroom team clearly understands that principle.
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eronald
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« Reply #99 on: January 14, 2013, 09:18:47 PM »
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From my perspective, Lightroom is a very nice light-table, filing and printing program with a good-enough Raw converter. If you want superlative Raw conversion, and only raw conversion, you can often get it for free with the manufacturer's software eg. Canon DPP, freeware like RPP, or resort to boutique products like Iridient's Raw Developer, or even Capture One which I believe quite a few people on this forum have used.

Edmund

Hi,

For me Lightroom was exactly the program I wanted to write, but I estimated it at 30-100 man years, longer than I plan to live.

Best regards
Erik


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