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Thread: CMOS Look, CCD Look in MF Sensors

  1. #51
    Senior Member ErikKaffehr's Avatar
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    Re: CMOS Look, CCD Look in MF Sensors

    Hi,

    I wouldn't think so, but you never know. The Sony A7s which is intended for video and low light has relatively fat pixels. The main advantage of fat pixels is that they allow for somewhat higher ISOs, the main disadvantage is that they are very prone to aliasing.

    If we look at the P45 that has 6.8 micron pixels it needs to be stopped down to f/16 to by and large eliminate colour aliasing. With 9 micron pixels we would need to stop down to f/22, while with 5.2 microns we would see little aliasing at f/11. Both the new CMOS 50 MP and the IQ-280 are at 5.2 microns.

    I would argue that a 5.2 micron image downscaled to say 39 MP will always be superior to a 6.8 micron image yielding 39 MP naturally.

    Also, keep in mind that the only cases we look at pixels without resizing are:
    • Looking at an image at actual pixels, known as pixel peeping
    • Printing an image at native printer resolution, ignoring size, and looking at that picture at 25 cm range.


    With video, resolution is limited to 2 MP (high definition) or 8 MP (4K), so it may be advantageus to use large pixels with heavy OLP filtering. Even better is to use small pixels, without pixel and line skipping and downscale in image processing, but that takes a lot of CPU-power. But, that is the way to do sharp and unaliased video.

    Best regards
    Erik




    Quote Originally Posted by Lobalobo View Post
    Wonder whether the fat CFA will come back into style, at least as an option on some CMOS sensors, when CCD sensors are no longer being manufactured, inasmuch as at least a minority of photographers prefer the look.
    Last edited by ErikKaffehr; 1st January 2015 at 07:32.

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    Re: CMOS Look, CCD Look in MF Sensors

    Quote Originally Posted by ErikKaffehr View Post
    Hi, I wouldn't think so, but you never know. The Sony A7s which is intended for video and low light has relatively fat pixels.
    Thanks but my post is about fat "CFAs" not fat pixels. "Fat CFA" is not my term but is explained above in another post as narrow-color definition in the filter, allowing finer grades of color distinctions.

  3. #53
    Senior Member ErikKaffehr's Avatar
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    Re: CMOS Look, CCD Look in MF Sensors

    Hi,

    Sorry, I missed that it was "fat CFA" nio fat pixels.

    Best regards
    Erik

    Quote Originally Posted by Lobalobo View Post
    Thanks but my post is about fat "CFAs" not fat pixels. "Fat CFA" is not my term but is explained above in another post as narrow-color definition in the filter, allowing finer grades of color distinctions.

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    Re: CMOS Look, CCD Look in MF Sensors

    Quote Originally Posted by ErikKaffehr View Post
    Hi,

    Sorry, I missed that it was "fat CFA" nio fat pixels.

    Best regards
    Erik
    No need at all to apologize. I'm grateful that you are willing to share your expertise.

  5. #55
    Senior Member ErikKaffehr's Avatar
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    Re: CMOS Look, CCD Look in MF Sensors, profiles matter more?

    Hi,

    I am doing some checks with different calibration tools, ColorChecker Passport, DNG Profile Editor and QPCard software.

    What I can see that the profiles generated by these tools may play a more significant role than the sensors themselves.

    Another thing that I have seen quite obviously is that at least when using Lightroom changing exposure will shift colour when using Adobe Standard profiles.

    This is coming from "hue tweaks" Adobe does colour. It is described pretty well in this article: ChromaSoft: Visualizing DNG Camera Profiles Part 1 , but my experiments confirm it very well.

    I need to look into other raw converters, how they handle this.

    I plan to post some notes on this in a few days.

    Best regards
    Erik

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    Re: CMOS Look, CCD Look in MF Sensors, profiles matter more?

    Quote Originally Posted by ErikKaffehr View Post
    Hi, I am doing some checks with different calibration tools, ColorChecker Passport, DNG Profile Editor and QPCard software. What I can see that the profiles generated by these tools may play a more significant role than the sensors themselves.
    Well that is really interesting and perhaps useful to those who have commented on this thread that they see differences in the CCD versus CMOS look, and like the former. If this is a matter of calibration to whatever look is desired, then the CMOS sensor may well be to everyone's taste (at least if the calibration can be done once for a sensor rather than on an image-by-image basis).

    Quote Originally Posted by ErikKaffehr View Post
    Another thing that I have seen quite obviously is that at least when using Lightroom changing exposure will shift colour when using Adobe Standard profiles.
    Although this is out of my league (actually all of this is) others have commented that PhaseOne Sensors need to be converted with Capture to preserve fidelity and allow maximum image quality. Even using small-sensor cameras, I see a difference between conversion with native software and third party software. You are the expert here, not me, but I wonder whether this could explain the color shift with exposure change.

  7. #57
    Senior Member ErikKaffehr's Avatar
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    Re: CMOS Look, CCD Look in MF Sensors, profiles matter more?

    Hi,

    I am no expert, just a curious person trying to understand what happens.

    The test I just made was very simple. I have two shots of the same IT-8 test target shot 2/3 EV apart. I adjust both raw images to match target grey values.

    With Adobe Standard profile I get a difference about DE = 1.7. Removing the hue twists from the Adobe Standard profile using Sandy's tools I get a difference of DE=0.32. Now DE 1.7 is not a large difference, but it makes it quite obvious that exposure differences do affect colour rendition, and this is caused by the way profiles are made.

    Need to find out how Capture One behaves on the same samples. Update: Checked Capture One and it shows no (or very small) colour changes with exposure change.

    Best regards
    Erik




    Quote Originally Posted by Lobalobo View Post
    Well that is really interesting and perhaps useful to those who have commented on this thread that they see differences in the CCD versus CMOS look, and like the former. If this is a matter of calibration to whatever look is desired, then the CMOS sensor may well be to everyone's taste (at least if the calibration can be done once for a sensor rather than on an image-by-image basis).



    Although this is out of my league (actually all of this is) others have commented that PhaseOne Sensors need to be converted with Capture to preserve fidelity and allow maximum image quality. Even using small-sensor cameras, I see a difference between conversion with native software and third party software. You are the expert here, not me, but I wonder whether this could explain the color shift with exposure change.
    Last edited by ErikKaffehr; 2nd January 2015 at 17:39.

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    Re: CMOS Look, CCD Look in MF Sensors

    I'm a bit rusty here so forgive me if some of the details here is incorrect, but in large it should be; a DNG/DCP profile makes the base color through a matrix (straight linear conversion from the sensor's RGB channels, multiplied with white balance), and then it can have two color adjustment maps, one "huesatdelta" and one "looktable". Both tables have the same format but they are applied differently.

    The first is applied before any adjustments (exposure curves etc), and the purpose of this table is to calibrate color, say if the sensor has a tendency towards green in underexposed areas that can be compensated for. The "looktable" is instead applied after any exposure adjustments and intended for a subjective look.

    I think most DCP profiles that Adobe provide via Lightroom has only the look table.

    Then one needs to be aware of that any curve/contrast change will cause color shifts. Capture One uses simple RGB contrast curves, which means that if a color has say 10%R, 80%G and 50%B and you apply an S curve R will decrease, G will increase and B stay the same, ie you have a saturation increase and a color shift. Adobe has a slightly different varaint of the RGB contrast curve, but for the most part it looks the same.

    You can make a contrast curve in the luminance channel, but that will look dull and desturated to most, so the saturation-increasing (and somewhat color-shifting) film curves are intentional. When you fine hand-tune a profile to make pleasing color rendition it's thus important to realize that it will only look the way you intend with the exact same curve as used when making the profile, and yes also the same exposure of the colors.

    Therefore I'm very skeptical about changing film curve from the standard (which you can do in Capture One) and still expect the "magic" hand-tuned colors to be there.

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    Re: CMOS Look, CCD Look in MF Sensors

    When it comes to comparing CCD vs CMOS I think there's some historic stuff involved, ie there's fat pixel CCDs vs antialiased CMOS. Older CCDs are quite noisy and have certain grain or texture which may be visible at 100%, and amplified by the lack of AA filter. Antialiased CMOS can look too smooth and "plastic" in comparison. On a distance or scaled down that should even out though.

    Then there's color profiling, with the MF guys making a good job to make skin tones look good in studio conditions, while traditional CMOS has been more about all-around use. I also think that MF users are more likely to use the native raw conversion tool than DSLR users were, ie you compare your DSLR with Lightroom conversion to your Hasseblad with Phocus conversion which is not really fair. On my Canon, Canon native software certainly present colors much better than say Lightroom.

    Today with CMOS available in various MF incarnations I think the view of that there is a special CCD look will fade away. There may still be a problem to some that they are "too clean" though regarding texture...

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    Re: CMOS Look, CCD Look in MF Sensors

    While I chose to use a camera with the Sony CMOS over the Dalsa CCD, I did see a difference in the image out of camera at base ISO that favoured the CCD. Way long ago, the difference could have been chalked up to the AA filters defiling the files on 35mm cameras. But it's more than that. While i have no empirical basis (or desire) to 'prove' it, my experience tells me that the CCD rendered some colours better natively in a way that is challenging to reproduce with the CMOS, and that the CCD files looked somehow snappier out of camera. But *is very subtle*.

    Personally, I have found that judicious use of local area contrast enhancement and sharpening in LR can equalize the 'look' substantially. To a level where it does not matter to me and that other, substantial, advantages of the CMOS chip win out.

    Colour is a more interesting question. The most graphic illustration i ever witnesses was the Fuji X-Pro1 vs the M9. The Fuji has gorgeous colour. The Leica Ms have struggled mightily with colour. However, when testing Fuji, I shot a series of images in brightly graphittied alleys, to test the colour response. The Leica rendered colours and subtleties I simply could not replicate with the Fuji - even though the Fuji files were luscious and I would never have wanted for more absent the comparison.

    The best i can add to this fractious, and ultimately pointless, debate is that, while some difference is real, CMOS is so much better in more important ways (cost, ISO/DR, Liveview) that this functionally ends the debate.

    Also, it must be remembered that for work the ends up in print, the actual differences are almost certain to be lost in press process, as they are on the web. The number of people involved in these debates who are making exhibition prints upwards of 16x20 is much smaller than the number of voices...

    None of which is to say that a preference for CCD-based cameras, and their output is not a legitimate reason to chose one. Many superb photographers chose these tools because what they produce simply pleases them more and makes them enjoy the work and streamline their process. And there ain't nothing wrong with that.

    Only question is when CCD cameras will become collectors' items :-)

    - N.
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    Re: CMOS Look, CCD Look in MF Sensors

    Quote Originally Posted by Nick Devlin View Post
    The best i can add to this fractious, and ultimately pointless, debate is that, while some difference is real, CMOS is so much better in more important ways (cost, ISO/DR, Liveview) that this functionally ends the debate.
    Yes, that's really the nub of the matter - any perceived advantage CCD backs have (if indeed they do) are easily swept aside by the added functionality that CMOS brings - particularly clean high ISO, DR and Liveview.

    Such a shame HB are raising the price of the CFV50c in Japan to match pricing elsewhere. From what I hear this has more to do with tantrums from dealers overseas than it has to do with economic realities. HB are presented with an opportunity to shoot themselves in the foot ... and they end up blowing their leg off. Sigh. Even at $15k it's still one hell of a proposition compared to the the IQ150/250, but at ~$10k it broke new ground. Oh well.
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  12. #62
    Senior Member ErikKaffehr's Avatar
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    Re: CMOS Look, CCD Look in MF Sensors

    Hi,

    You can get the same sensor below 10k$ with the Pentax 645Z, camera included. The CFV 50c is of course a great boon for Hasselblad V-series owners, but the 1.3X crop factor limits the wide angle side.

    Still, the CFV 50c is low cost compared to the H5D-50c.

    Best regards
    Erik

    Quote Originally Posted by f8orbust View Post
    Yes, that's really the nub of the matter - any perceived advantage CCD backs have (if indeed they do) are easily swept aside by the added functionality that CMOS brings - particularly clean high ISO, DR and Liveview.

    Such a shame HB are raising the price of the CFV50c in Japan to match pricing elsewhere. From what I hear this has more to do with tantrums from dealers overseas than it has to do with economic realities. HB are presented with an opportunity to shoot themselves in the foot ... and they end up blowing their leg off. Sigh. Even at $15k it's still one hell of a proposition compared to the the IQ150/250, but at ~$10k it broke new ground. Oh well.

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