Is image quality better on FF than DX

Discussion in 'Digital Photography' started by trjwv, Sep 14, 2010.

  1. trjwv macrumors regular

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    #1
    Is the image quality better on an Full Frame than the DX? I know the sensor is bigger but keeping the MP's the same (12mp), will the image be better?
     
  2. G.T. macrumors 6502a

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    Jul 12, 2008
    #2
    In theory yes. It will be better at having less noise at higher ISO's. As the the "pixels" so to speak are not crammed to a smaller sensor.

    Also the lens focal length will not be cropped, while this won't affect quality (as far as I know) you will be able to capture more as a wide angle lens will be used to its full potential. Also I suppose in terms of the quality of image if u like using the Bokeh effect then it will also be better on a full frame than a cropped e.g. a f2 aperture on full frame with have a shallow depth but on say a micro 4/3rds the f2 aperture will have a bokeh equivalent to f4 so not as shallow. On either sensor though they should still let in the same level of light.

    Correct me if wrong.
     
  3. Phrasikleia macrumors 601

    Phrasikleia

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    #3
    The full-frame sensors tend to have more dynamic range and color depth, and if you shoot raw, the bigger sensors usually allow you to pull more detail out of the shadows.

    The thing with megapixels and noise is that when you reduce a high-resolution image in size, the pixels become 'smaller,' including the noisy ones. So a high-resolution image that has some evident noise may look very similar to a lower resolution photo that has no noise, once the higher resolution image is scaled down.
     
  4. OreoCookie macrumors 68030

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    #4
    Not necessarily, what determines the physical limits is pixel density. So the advantage of full frame sensors is that they either allow for much larger resolution or for lower pixel density which improves the theoretical limits regarding noise behavior and dynamic range.

    Generally speaking, full frame sensors do have lower pixel density and thus perform better. However, if you have a full frame camera, you need very good lenses -- and making lenses that perform well on full frame tend to be more expensive than lenses which perform well on crop sensors.

    Olympus' pro lenses, for instance, are often more compact than their full frame counter parts and offer stellar optical performance. The downside is that Olympus' cameras cannot compete with modern full frame cameras when it comes to (very) high ISO behavior.

    Image quality is determined by the whole optical system and not just by the sensor.
     
  5. toxic macrumors 68000

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    Nov 9, 2008
    #5
    based purely on image quality, bigger is always better. the larger the original image, the less it needs to enlarged to the final viewing size. for the same reason, larger sensors don't need as high quality optics to realize the same image quality as a smaller sensor (less enlargement magnifies aberrations less).

    pixel density only comes into play when you have to crop.

    so to answer the original question, a 12MP 24x36mm sensor will have better IQ than a 12MP 16x24mm sensor, and you can use a 1.5x weaker lens on the 24x36mm sensor and still have the same IQ as with a stronger lens on the 16x24mm sensor (assuming no cropping).
     
  6. miloblithe macrumors 68020

    miloblithe

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    #6
    Big however...

    lenses for DX are in some respects better because they don't use the extreme edges of the frame. Almost all lenses are softer and darker in the corners. On a DX camera, these issues are less important because the sensor doesn't record information from as far to the corners as a full-frame sensor does.

    Additionally, as mentioned earlier, because of the depth of field on a full frame sensor is narrower at the same f-stop, less will be in focus. In terms of image quality (which is a pretty broad term full of different and even opposing concepts), that can be an advantage or a disadvantage depending on the type of picture you're trying to take.
     
  7. Ruahrc macrumors 65816

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    Jun 9, 2009
    #7
    That argument only applies to FX lenses used on DX bodies. The lenses made specifically for DX have smaller image circles and thus the sensor is "looking" just as far into the edges as is in the FX case.
     
  8. miloblithe macrumors 68020

    miloblithe

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    #8
    True enough, although it can be argued that it's also easier to design lenses that only cover the DX frame, so DX-only lenses may have better corners than FX lenses on FX cameras. Obviously it depends on the lens. While the corners of $100 kit 18-55 lenses are probably not all that impressive, the corners on the $1000 Nikon and Canon 17-55 lenses are probably better on DX sensors than the corners on their 24-70 lenses are on FX lenses, for example. Maybe not those specific lenses, but you get the idea.
     
  9. carlgo macrumors 68000

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    #9
    You can ask this question a hundred times and mostly you get theory about pixels and such, or that resolution doesn't matter, etc.

    I suggest borrowing or renting to see what the differences are, or aren't, for the photos you take and print.
     
  10. toxic macrumors 68000

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    Nov 9, 2008
    #10
    yeah...if all you do is post images online or make 4x6 prints, there won't be much of a difference. it will only matter if you make larger prints (say 12" on the short side, at minimum).
     
  11. mmoto macrumors member

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    Mar 21, 2009
    #11
    I've seen some stunning 40x60" prints generated using a Nikon D100 (6MP DX sensor) and smart upscaling. A modern full frame sensor might have given the photographer more latitude but I doubt it have improved the print quality much.
     

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