1Dx, rumoured D800 and the diffraction question

Started Oct 19, 2011 | Discussions thread
Severian The Lame Contributing Member • Posts: 550
Re: 1Dx, rumoured D800 and the diffraction question

buellom wrote:

Hi all,

just wondering where the limits of the „returns on investments“ are when a camera has more pixels. Beside noise there has diffraction to be considered.

At the-digital-picture.com you find a table where the Diffraction Limited Aperture (DLA, see last column) is calculated for several Canon cameras:


I understand that “higher resolution sensors generally continue to deliver more detail well beyond the DLA than lower resolution sensors”, but nevertheless I would like to know where diffraction kicks in with the

Canon 1Dx (FF, 18 MP), Sony A77 (APS-C, 24 MP) and the rumoured Nikon D800 (FF, 36 MP).

Thanks in advance for your replies.

Best, Buellom

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Diffraction doesn't suddenly "kick in". It is always present. And sensor resolution has nothing to do with diffraction per se. The limits referred to in the "DLA" mentioned in your quote are very soft limits, not a hard limit where some scary bad diffraction stuff kicks in! Moreover, the DLA is mostly only relevant to pixel peeping at 100%. You shouldn't sweat about these things. On the other hand, it's a rare occasion when I would go over f/13 on APS-C, no matter the resolution of the camera.

Nonetheless, I present for your delectation the following chart (the vertical bars are the Nyquist limits of the respective sensors):

The graphs below show the influence of diffraction on a reasonably sharp lens. The MTFs were generated using slanted edge analysis of 7D raws (converted in LR 3 with default settings except for custom white balance) of an ISO 12233 test chart. Note that while lens MTF can never be better than the diffraction limit (the black curves below), the total system frequency response can.


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