If I take a Canon 5DS R (50.6 MP), which has high resolution and no anti-aliasing filter, and then I take a Canon 6D (20.2 MP) and shoot the same scene with both, both using the same capable lens (i.e., Zeiss Sonnar or Otus), and then resize to 1920 x 1080, will I see a difference in sharpness?

If yes, I'd be even more happy if you can provide a comparison image.

I read that it also matters how the software does the resizing.

  • As to your implied side-question about resampling methods, there's a pretty good overview in the ImageMagick docs, but ultimately your own subjective evaluation will be more meaningful. Mar 22 '16 at 1:43

If your final output resolution is going to be 1920 x 1080 then the only advantage of a 50MP camera over a 20MP camera is the ability to crop a little over twice as tight with the 50MP camera than with the 20MP camera and still have resolution of at least 1920 x 1080.

And that assumes the resolution limit of the lens doesn't get you first. If the imaging sensor can out resolve the lens then the limiting factor is the lens, not the sensor.

The difference between one camera with an anti-aliasing filter and another without one will totally depend on the contents of the scene (are there any repeating patterns that could cause moire), the amount and type of sharpening applied, and the software used to reduce the images to 1920 x 1080.

  • dpreview.com/forums/post/57481909
    – icor103
    Mar 22 '16 at 18:16
  • 1
    Without knowing the difference in the two in-camera sharpening algorithms used for the two examples that comparison is useless, as the poster of that link acknowledges in his comment included with it.
    – Michael C
    Mar 22 '16 at 22:13
  • 2
    @icor103 The last paragraph of the above answer pretty much says the exact same thing as your link does.
    – Michael C
    Mar 22 '16 at 22:14

Probably not much difference remaining.

50.2 megapixels is 8712x5808 pixels.
20.2 megapixels is 5505x3670 pixels.
(based on your megapixel numbers, I did not look up the sensors).

1920x1080 is 2.07 megapixels, so substantially less detail is possible.

A pixel is the smallest dot that can be reproduced, the smallest detail that can be reproduced.

8712 down to 1920 pixels is 4.5 to 1, or 1 pixel remains for every 4.5 pixels of width.

5505 down to 1920 pixels is 2.87 to 1, or 1 pixel remains for ever 2.87 pixels of width, which was itself only one pixel for every 1.58 pixels in the 50mp image.

This of course assumes the lens and scene did in fact transfer the maximum possible detail. Not always the case. Situations vary.

Expectations of 50 mp or 20 mp of detail in 2 mp of image are not very realistic. :) It might be a real good 2 mp image, but 2 mp cannot be better than that, detail wise.

In these two cases, resampled resolution will be 1/4.5 or 1/2.87 of the theoretical maximum original detail originally possible. In any case, it cannot be more detail than 1920 pixels can show.

  • dpreview.com/forums/post/57481909
    – icor103
    Mar 22 '16 at 18:16
  • @icor103 No need to just keep reposting links to the discussion you started on dpreview.com in the comments for these answers. Please provide some context for the point you're trying to make in the comments.
    – scottbb
    Mar 23 '16 at 2:34
  • note that "photographic" 2 megapixels is less than full HD 2 megapixels - because of the limited color resolution: each sensor pixel only receives either R, G or B information, while on screen we have full RGB for each of the 1920x1080 pixels.
    – szulat
    Mar 23 '16 at 3:26
  • @szulat Do you understand what happens during demosaicing? Assuming each camera has at least 1.414X (√2) resolution of full HD, that is 2716x1528=4.15 MP then there will be the same or more capacity for resolving line pairs no matter what the color of the pairs. With standard B&W line pairs there is no loss of resolution because white contains R, G, and, B.
    – Michael C
    Nov 19 '16 at 9:56
  • 1
    @szulat And the intent in my response is to say that when speaking of 20 MP and 50MP cameras it makes absolutely no difference when images from both are downsized to 2 MP on a screen.
    – Michael C
    Nov 20 '16 at 22:08

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