Resolution of 1 layer versus 3 layer image sensors

Discussion in 'Hardware' started by Herman, Sep 29, 2010.

  1. Herman

    Herman Mu-43 All-Pro

    Feb 7, 2010
    The Netherlands
    The Sigma SD1 has a X3 (46MP, 3 layer) image sensor.
    The Pentax K-5 has a 16,3MP 1 layer (right?) image sensor.
    Does this really mean that the SD1 has much better quality output than the K-5 ?:rolleyes:
     
  2. f6cvalkyrie

    f6cvalkyrie Mu-43 All-Pro

    Feb 12, 2010
    Brussels, Belgium
    Wikipedia remains your best friend, Herman.

    Here's a link for the Foveon sensor :

    Foveon X3 sensor - Wikipedia, the free encyclopedia

    Picture quality being very difficult to define, I could really not tell you if the Foveon is the better sensor. However, it does have quite a reputation in the colour rendition field !

    Hope this helps,
    Rafael
     
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  3. deirdre

    deirdre Mu-43 Top Veteran

    661
    Aug 9, 2010
    From that Wikipedia article:

    With the introduction of the Sigma SD14, the 14 MP (4.7 MP red + 4.7 MP green + 4.7 MP blue) Foveon X3 sensor resolution is being compared favorably by reviewers to that of 10 MP Bayer sensors. For example, Mike Chaney of ddisoftware says, "the SD14 produces better photos than a typical 10 MP dSLR because it is able to carry sharp detail all the way to the 'falloff' point at 1700 LPI whereas contrast, color detail, and sharpness begin to degrade long before the 1700 LPI limit on a Bayer based 10 MP dSLR."[26] Another article judges the Foveon X3 sensor as roughly equivalent to a 9 MP Bayer sensor.[27] A visual comparison between a 14 MP Foveon sensor and a 12.3 MP Bayer sensor shows Foveon has crisper details.[28]
     
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  4. Brian S

    Brian S Mu-43 Top Veteran

    714
    Apr 11, 2009
    If the single-layer 15.6MPixel sensor is Monochrome, it would be the same.

    If the single-layer 15.6MPixel sensor is color using a Mosaic Filter, the Foveon is much better.
     
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  5. Herman

    Herman Mu-43 All-Pro

    Feb 7, 2010
    The Netherlands
    My conclusion: Sigma has the superior sensor, right.
    Who moves to Sigma ? Or already has ?
     
  6. andrewteee

    andrewteee Mu-43 Regular

    33
    Apr 14, 2009
    I have various Bayer cameras and the Sigma DP1s and DP2s. I can tell you without a doubt that the Sigma cameras universally resolve far more detail than the Bayer cameras. At 3x the current Foveon sensor the SD1 is virtually guaranteed to be incredible. The Sigmas are great B&W cameras too.

    But the Sigma cameras are not the easiest to use and can at times be infuriating. I treat my DPx cameras like medium format - I often use a tripod and manual focus and work methodically.

    The Foveon sensor is obviously unique and it has a unique rendering (many say film-like). Another important point is that the Sigma cameras lack any AA filter. That absolutely helps with the resolving capabilities.

    Here are a few samples in B&W and color. I also shot the same thing with my Bayer-based Ricoh GXR/A12 and though those pictures are very good the DP2s pictures were that much better.

    Junior | Flickr - Photo Sharing!

    Wee Scooter This Is What I Saw
     
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  7. Maczero

    Maczero Mu-43 Regular

    141
    Feb 13, 2010
    Fife
    I have a DP2 and second everything about them being infuriating to use - but when you get it right: Wow!

    The DR is pretty good (you need to expose to save the shadows and recover the highlights later)

    Oh for a Foveon sensor in an Olympus mu43 body ...
     
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  8. feppe

    feppe Mu-43 Regular

    The consensus seems to be that Foveon sensor megapixel count when converted to Bayer array equivalent (as much as that's possible theoretically and in practice) is around 2x, not 3x. Sigma engineers have accepted the 3x claim to be marketing speak.

    Also, there's much more to image quality than mere megapixels. But the upcoming Sigma does sound mouth-watering - if I only didn't have an investment in Canon gear already.
     
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  9. photoSmart42

    photoSmart42 Mu-43 Top Veteran

    628
    Feb 12, 2010
    San Diego, CA
    If the SD1 actually comes out early next year, and if it delivers on IQ and quality I'm buying one. I don't mind treating it like a medium format camera since I'm already used to that. It would sure be a cheaper alternative to a MF digital back, and perfectly fine for the size prints I want to produce.
     
  10. Boyzo

    Boyzo Mu-43 Top Veteran

    784
    Mar 3, 2010
    Herman read this review (prelim) the new Sigma SD1 DSLR
    Sigma releases SD1 flagship digital SLR: Digital Photography Review

    The weakness of the Bayer sensor is Red but Panasonic have over the years improved this weakness greatly.

    The Fovian has advantages no doubt but I don't see myself ever going to one after all the Leica M9 uses a Bayer sensor ... and they should know :wink:
     
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  11. andrewteee

    andrewteee Mu-43 Regular

    33
    Apr 14, 2009
    Let's face it - the AA filter is no good. Software should be able to play that role now. Minimizing (Olympus E-PL1) or removing (Sigma, Leica M9) the AA has only positive benefits. Allow the detail to come through!
     
  12. feppe

    feppe Mu-43 Regular

    Software can't do what AA filters do - it's impossible to recreate anti-aliasing in post-production due to physics. Yes, there are AA filters in software packages, but it's not the same thing as a low-pass filter in front of the sensor.

    Also, removing the AA filter doesn't necessarily increase sharpness. What it does is increase perceived sharpness by introducing aliasing artifacts (jagged edges, ie. not real information). Sensors without AA filters (medium format mainly) also have problems with moire in fabrics and other repeating patterns, which is very difficult to get rid of in post.

    A certain level of AA filter is desirable. I agree that many DSLRs have AA filters which are too strong, but eliminating it altogether will not help mainly due to moire, but also because it does creates artifacts rather than retain real information.

    As a sidenote, I wasn't aware the E-PL1 has a weak AA filter. That might explain why I was utterly shocked when I printed my first 13x19" photo from mine, and compared to prints made with a Canon 550D - it held up remarkably and produces very good prints at that size!
     
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  13. andrewteee

    andrewteee Mu-43 Regular

    33
    Apr 14, 2009
    Thanks Feppe. So that would imply there is more to Foveon that just a lack of AA filter. I wonder if the sensor design avoids moire issues. And I wonder what they do in the M9 - do the micro-lenses deal with moire?
     
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  14. feppe

    feppe Mu-43 Regular

    That's exactly the case. I'm not an expert on the matter, but my understanding is that since RGB sensors in a Bayer Array are in an... array, they need to be combined to yield a single color pixel. This is more prone to moire than Foveon sensors, where the RGB sensors are on top of each other. Quick googling seems to confirm this - Foveon doesn't have color moire, but does suffer from luminance moire.

    Micro-lenses don't deal with moire. In M9 they are designed to deal with vignetting with wider lenses. The angle of light hitting the sensor is acute due to the back of the lens being so close to the sensor in the Leica design that it causes headaches for sensor designers. Workaround was micro-lenses which re-direct the light. Similar issues plague medium format digital sensors and tilt-shift lenses.

    Here's a very nice (not too) technical explanation on the differences between Foveon sensors and practically every other digicam sensor. I really hope SD1 delivers on the very impressive specs, and comes out soon - Sigma has been notorious with loooong delays between announcement and launch.
     
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  15. Herman

    Herman Mu-43 All-Pro

    Feb 7, 2010
    The Netherlands
    Thanks for the replies.
    How does the Foveon sensor deal with high ISO settings?
     
  16. gcogger

    gcogger Mu-43 Veteran

    343
    May 25, 2010
    UK
    Graeme
    Badly, in previous cameras...
     
  17. photoSmart42

    photoSmart42 Mu-43 Top Veteran

    628
    Feb 12, 2010
    San Diego, CA
    It's not a high ISO camera, nor is it a fast focus camera, nor is it a fast frame rate camera. Think of it as a small medium format digital back. It's meant primarily for studio work, landscapes, not very fast-moving 'action' and people. Foveon sensors need a lot more light (they use up 3x the amount of light per area), so generally their ISO settings/range is quite low (up to 800, perhaps 1600 but probably noisy even at those settings). It remains to be seen how this new sensor design deals with higher ISO settings. If you shoot stills and generally stick below ISO 800 (like I do), often on a tripod, this is the camera for you.