Megapixels vs Quality

Discussion in 'Digital Photography' started by MBX, Sep 21, 2008.

  1. MBX macrumors 68000

    Sep 14, 2006
    What's the point of higher megapixels if the image-quality is crap = Noisy?

    Anyone know if selecting lower megapixel-amount on the same camera providing high mp's will increase image quality when using lower mp settings?
  2. seenew macrumors 68000


    Dec 1, 2005
    More detail at the expense of adding noise. Not too noticeable in well-lit scenarios, but more so in others. As for the other question, I believe it depends on the camera...
  3. volvoben macrumors 6502

    Feb 7, 2007
    nowhere fast
    changing the image size in the camera will do nothing to change image quality. All it does is downsize the file made in camera, it can't magically create larger photosites that capture more light.

    More megapixels are usually just marketing BS, but if the lens is of good quality, some cameras can take advantage of their higher pixel counts with sharper images...but under less than ideal lighting they're still junk...and of course they never have great lenses either...

    Perhaps at some point they'll come up with a good way of marketing low light performance or sharpness etc...
  4. anubis macrumors 6502a

    Feb 7, 2003
    Unless the OP is talking about pixel "binning", which only a few cameras support. Binning reduces noise, but if you find yourself needing to do this for a lot of your shots, might as well save a lot of money and just buy a lower MP camera.

    Serious amateurs and professionals are fully aware that, in general, more MP = more noise unless a mitigating factor exists (gapless microlens, high quality photodiodes, etc.) General consumers are all getting suckered into the higher MP = higher quality, though.
  5. OreoCookie macrumors 68030

    Apr 14, 2001
    Sendai, Japan
    Higher megapixels have other disadvantages, two very relevant ones are (i) the diffraction limit and (ii) quality of lenses: there is a reason crop sensors (effectively) top out at 12-14 MP and Olympus chose an even smaller pixel count.

    (i) If you cram more pixels onto a sensors, the side lengths of the sensor get smaller and diffraction sets in earlier. The diffraction limit says that from a certain aperture on, you can see non-linear effects (linear optics no longer holds). The smaller the pixel, the earlier the onset of diffraction. With 1.5x crop sensors, you start to see effects at around f/11, with 4/3 cameras at around f/8.

    If you increase the pixel count to -- say -- 50 MP (which I reckon you could technically do), it would be very hard to impossible to construct a usable lens for it. You simply need larger-format sensors. Even with full frame sensors, I don't expect to see anything beyond roughly 25 MP.

    (ii) More resolution means that you can see flaws in the optics more easily. Very often, you can get essentially the same P&S with different sensors. No matter what's written on the lens (Carl Zeiss, Schneider-Kreuznach, whatnot), there is no way you can get good-enough resolution for 10+ MP sensors with lenses the size of (smallish) coins. Most of the time, the resolution is limited by the optics (which is hard to advertise compared to pure megapixels). These high-res sensors are particularly useless for people who very rarely print anything larger than 10x15 cm^2.
  6. mrgreen4242 macrumors 601


    Feb 10, 2004
    I wonder if they could start advertising MP-equivelents. Like AMD did with the Athlon vs. the P4... Put a 6MP sensor in a camera and then compare it to a 10MP camera shooting a line resolution chart showing the number of lines per inch it can resolve at different ISOs. Seems like the noise will kill the fine detail resolution giving the two similar "scores". I agree that there needs to be some sort of new metric for camera quality.
  7. MBX thread starter macrumors 68000

    Sep 14, 2006
    Why is there not more outrage and protest in the industry against this silly megapixel craze? I'm speaking especially about professional (dslr) and semi-professional (advanced point & shoot) cameras.

    Why can't they leave the silly megapixel-wars up to the tourist and amateur p&s cameras? It's not like we pro and semi-pro people are as stupid but want good cameras with great quality instead of silly megapixel amounts.

    On another note:

    When i read the reviews on the Panasonic Lumix DMC-FX150 everything sounded so fantastic! I went on to buy it yesterday, tested it and it's total CRAP!

    Not only is it's raw-files not supported by Aperture and Lightroom (but that's a different story) but the image quality is total BS. I can halfway live with noisy jpg's because i thought ok it's jpg-compression. But it's Raw-images (i had to open them with the software that comes with the CD) are a disgrace and insult! Totally noisy, as if you applied a noise-filter in photoshop.

    I don't know why DP-Review doesn't do a better job at reviewing cameras and actually testing it themselves. It seems they get the info and reviews directly from the manufacturers, have a look:

    Other reviews were pretty much exactly the same. It seems not many outthere actually test the cameras when putting out these reviews.
  8. butterfly0fdoom macrumors 6502a

    Oct 17, 2007
    Camp Snoopy
    DPReview does review cameras. But they don't review every camera. On that sidebar there? There's a button that says "Reviews/Previews". You linked us to Panasonic's press release that DPReview republished.
  9. robbieduncan Moderator emeritus


    Jul 24, 2002
    And they do so very well. They're real tests are about the most comprehensive and exhaustive out there. Which is probably why they don't review every camera: each review must take ages to complete...
  10. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    It could. When you resize an image in the camera the camera could use a different interpolation method that favors noise reduction over sharpness. I really doubt that any camera creates reduced resolution .jpg files by first creating a full resolution image and then resampling the larger image. Much faster and better to go dirctly from raw to reduced size .jpg. This is not the same as making larger photosites but is close

    Some astronomical cameras can actually create larger photosites by changing the way charge is shifted off the sensor, the pixels are added together in the analog domane before they are digitized in effect making photosites that are 2, 4 or even 8 times larger but this cn't be done on a color mosaic sensor

    For a color sensor there is an optimal pixel size. it is around about 6 micro meters square. This works out to around 10 to 12 MP on a crop (DX or APS-C) senor or about 24MP on a full 24x36mm sensor. or around 50MP on a "645" size medium format camera
  11. Edge100 macrumors 68000

    May 14, 2002
    Where am I???
    In a sense, I agree with you. Back in the day, you could put Velvia in a P&S and get images that were only limited by the quality of the lens. These days, you have P&S cameras with better lenses (though not SLR-quality yet), but the sensors are just plain bad. A friend of mine has a 12MP Olympus that has an ISO6400 mode. It's an absolute joke.

    But re: pro/pro-sumer cameras (I'm thinking Canon X0D, 5D, and 1D-series or Nikon D90, D700, D300, D3 level cameras here, rather than very basic SLRs), I think more MP isn't necessarily a bad thing. We can see that the 5DmkII has (it seems) very low noise at 21MP (much better image-level noise than the original 5D). You take that 21MP image, crop it down to 1.6x to get your telephoto range back, and you're still looking at 8.2MP of excellent, noise-free IQ. In fact, that image may actually show better IQ and noise than a native 8.2MP image you might get from a 20D or 30D.

    On the other hand, if you have the glass to resolve those massive MP counts, you'll get ultra-high IQ. But for those who have crap (basically, in Canon-speak, non-L) glass, those MP are going to be a nuisance because they will show the faults of the lenses much more readily.

    So I agree in principle; it's becoming a little silly re: MP. But both Nikon and (especially) Canon have managed to go to very high MP levels and maintain very low noise. That, to me, is the best of both worlds. Get yourself some good glass to go with those bodies, and you're basically set for a LONG time. My next camera will be the 5DmkII, and I don't anticipate moving from that for many, many years.

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