Megapixels - is 16 MP really useful for you?

Discussion in 'Panasonic Cameras' started by rossi46, Mar 22, 2012.

  1. rossi46

    rossi46 Mu-43 Regular

    Mar 1, 2012
    I have been reading abit about Megapixels and the myths or truth...

    General opinions are that -
    1. Benefits of higher MP if you crop or enlarge
    What other benefits do we have for higher MP?

    But there are also some saying that too many MP will have its disadvantage on Image Quality -
    - noise level increase, especially in low light.

    Does this mean, when we are shooting in Low Light we have to reduce the megapixel level of our cameras?
  2. napilopez

    napilopez Contributing Editor

    Feb 21, 2012
    NYC Area
    Real Name:
    Napier Lopez
    Well, see, pixel quantification is such an iffy issue. Yes, generally more MP means that you can crop and/or enlarge and image more, but this isn't always the case, and is probably not the case for M43 cams, or not largely so. Basically, megapixel counts in cameras generally tell you the amount of photosites on a sensor, but what they fail to mention is that each photosite isn't collecting unique information. Sensors typically have something like 50% green pixel sensors, 25% blue, and 25% red, meaning that each individual photosite can only detect one color, either red, green, or blue. The camera uses software to "guess" the colors it can't detect based on neighboring pixels. Essentially, just because a camera is 16 megapixels, it doesn't mean each pixel is truly conveying unique information. Thats why rarely in 100% crops of images do you see details that are razor sharp. This is further exacerbated by the fact that most cameras have a filter which blurs the image slightly before arriving at the sensor in order to prevent some strange artifacts with patterns, moire.

    The only popular sensor with unique information for each photosite is the Foveon sensor used in Sigma's cameras. That's why it's pictures are so much sharper than any other sensors in its resolution class.

    But yes, generally speaking, given similar technology, less pegapixels will result in less noise. It's why the NEX-5n has less noise than the NEX-7, despite being an older, lower end camera. I think you really have to go on a model by model basis. For example, the Lumix G3 has much better low light performance than any of the 12mp sensor M43 cams. However, the "true" resolution of the image isn't that much sharper than that of the 12 megapixel sensors.
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  3. MajorMagee

    MajorMagee Mu-43 All-Pro

    Feb 24, 2011
    Dayton, OH
    This will start an ongoing debate, but there are a couple of things at issue here. More megapixels are good if you put them on a larger chip. Putting more on the original size chip means you have to make each one smaller.

    Smaller photo sites leads to two issues the first being that fewer photons can fit down the well at any given moment. This accounts for the reputation that you'll have more noise and struggle with low light detection. To some extent this is now being overcome electronically, but ultimately your're still limited by the available signal.

    The other problem is the simple physics of diffraction, in that once you go below a certain size for the detector sites the probability that your photon will fall into the correct well goes down rapidly as you reduce the size of your aperture. What this leads to is a reduction of the sharpness as what should be points of discrete light get spread over little local groups of detectors. The end effect of this data spreading is that you're working with fewer discrete detector sites, as if you had a lower MP sensor anyway. For normal images the difference is not very visible, but if your subject has very fine feature transitions, and you're blowing the image up significantly to take advantage of all these megapixels, you'll see the softening as the edges smear over.
  4. drewbot

    drewbot Mu-43 Top Veteran

    Oct 21, 2011
    Toronto, ON
    Anything higher than 16 MP and diffraction would not let us stop down past f 5.6
  5. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    Real Name:
    Megapixls describe the QUANTITY of information in a file not the QUALITY of information in a file. Dynamic range, bit depth, signal to noise ratios etc have just as much to do with image enlargement as does pixel count.

    Generally speaking sensors of the same size/type with more pixels are noisier than those with less at a pixe level. But print them at the same size and the differences usually dissapear. For example the NEX7 sensor is noisier than the NEX5n. But print them at the same size and theres only a very small difference.

    The neverending shots of test charts and brick walls are great for forums but in real life you're more likely to be limited by technique, light or opprotunity than you are by your camera.

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  6. KVG

    KVG Banned User

    May 10, 2011
    yyc(Calgary, AB)
    Real Name:
    Kelly Gibbons
    Yessss!!!!! You speak the unspoken truth!!!!

    Sent from my iPhone using Mu-43 App
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  7. pictor

    pictor Mu-43 Top Veteran

    Jul 17, 2010
    All other things equal, more pixels are better, because you get equally sized prints with improved quality or larger prints with the same quality.

    You are only right as long as sensor technology is the same. Technology improves and therefore new sensors with more pixels can be better regarding noise, low light, ... than older sensors with less pixels. The new 16MP sensor is better than the old 12MP sensor in low light because of technological improvements.

    Not as long as you don't increase the size of your prints. Looking at 100% crops of two equally sized sensors with different pixel counts means different enlargements and different impacts of diffraction. But if you look at equally sized enlargements, you won't see any stronger impact of diffraction. However, you will still see some improvement.
  8. songs2001

    songs2001 Mu-43 Top Veteran

    Jul 8, 2011
    More MPs are better for post processing. It's easier to mask smaller pixels than big fat ones.
  9. pictor

    pictor Mu-43 Top Veteran

    Jul 17, 2010
    You are right, if you have more pixels while all else is equal. The quality of the pixels matters. One cannot look at only one single property of an image, since image quality cannot be defined by one single property.
  10. Ray Sachs

    Ray Sachs Super Moderator

    Apr 17, 2010
    Near Philadephila
    As others have explained, it's kind of a wash. More pixels (all else equal) may mean more noise and more resolution. If you downsize the output, you lose both the good and the bad of that. I'd be perfectly happy with 10-12 mp - my favorite cameras are currently 10 and 12. But as technology improves the sensors, there's also a megapixel war on, so in m43, it's pretty clear that the existing and new 16mp sensors are better than the 12mp sensors that came before. So I accept the 16mp sensors as the only real downside is the larger file sizes to deal with. But given my druthers, I'd be just as happy to see those same improvements in 12mp sensors rather than 16. But I rarely print larger than 12x18", so my needs are not the same as everyone else's.

  11. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    What more pixels do:

    Increase resolution
    Increase file size

    What more pixels may do:

    Increase noise
    Increased cropping--if you crop in a lot (probably not a good picture anyway and the cropping is a bad fix).

    What having more pixels does not effect or limit:

    Print size
  12. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    This is totally dependent on the manufacturer and how they do things. Like in the example napilopez gave of the Sony NEX-7 vs. Sony NEX-5n, that shows that when manufacturers bump up the pixel count without the corresponding technology to back it, that you achieve the result that you describe - worse performance with larger files.

    On the other hand, manufacturers like Olympus do not increase the pixel pitch of their sensors until they have the technology to back it... making it an improvement in every way, not just filesize. Panasonic seems to do this too, but Olympus actually stated this idea publicly... and were ridiculed for it at the time, I might add... so they make a prime example.
  13. drewbot

    drewbot Mu-43 Top Veteran

    Oct 21, 2011
    Toronto, ON
    Diffraction will start to show its ugly head at larger apertures with a higher pixel density.
  14. Promit

    Promit Mu-43 All-Pro

    Jun 6, 2011
    Baltimore, MD
    Real Name:
    Promit Roy
    In a sensor, there are two ways to improve the output: better pixels, or more pixels. The latter implies worse data at 100%, but the idea is you very rarely use these photos at 100% crop or anything close to it. You have a set output size you want, and more pixels means that the image is downsampled to the final output, and downsampling tends to fix a lot of image flaws. Consider this passage from Thom's G3 review:
  15. ftwphoto

    ftwphoto Mu-43 Regular

    Dec 12, 2011
    Does dropping down the resolution in camera have a negative effect on picture quality? I mean outside of less megapixels, if two images were taken at different in camera sizes, would the less size have lower picture quality at the same viewing size?
  16. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    That does not matter. The only limit to diffraction is the format size. Just because you can compare two images at 100% and notice diffraction is not important. Images from the same format have the same diffraction limit based on permissible circles of confusion, not pixel pitch.
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  17. kinlau

    kinlau Mu-43 Top Veteran

    Feb 29, 2012
    Given the same level of technology, same generation of sensor, higher MP will mean more noise. However, that noise is fixed, you can't magically reduce the number of pixels in your camera, reducing the resolution only uses less pixels. Some cameras have a special high ISO mode that shoots at a reduced resolution by pixel binning, but I'm not aware of a m43 model that does that.

    But you still have the option of sizing down the image in photoshop, which will reduce the amount of apparent noise.
  18. thearne3

    thearne3 Mu-43 Top Veteran

    Jan 28, 2010
    Redding, CT USA
    I think it's interesting that even the square aspect ratio is still about 12mp with the new sensor. Not the same as having all 16 mp, as with the GH2, but it's nice...
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  19. kinlau

    kinlau Mu-43 Top Veteran

    Feb 29, 2012
    We don't all print 8x10's, and view them at standard distances. Cropping happens a lot, so you cannot assume format size.

    With the Panasonics, you also have ETC mode, which is pretty well a 100% blowup. I use it all the time in video mode, and we have people using adapted 16mm, c-mount tv lenses etc, so that part of the equation isn't irrelevant anymore.
  20. Jonathan F/2

    Jonathan F/2 Mu-43 Hall of Famer

    Aug 10, 2011
    Los Angeles, CA
    I'm a big fan of Olympus processing. I'd love them to apply their know-how onto a large FF sensor! Could you imagine how awesome a 36mp FX sensor would be with Olympus processing and Zuiko lens sharpness!!!! The fact they can maximize the 4/3rd sensor output is amazing in itself. Besides less DOF and extreme high ISO with the 4/3 sensor, Olympus is showing they can hold their own with the big boys.