24mp sensor for m43? 3.2micron pixel pitch!

Started May 9, 2013 | Discussions thread
RicksAstro Veteran Member • Posts: 3,837
Re: 24mp sensor for m43? 3.2micron pixel pitch!

Anders W wrote:

RicksAstro wrote:

Merak wrote:

The 24mp will reward you with a visible increase of diffraction compared to a rather small increase of resolution. With todays 16mp sensors f16 is heavily impacted by diffraction, f11 in most cases visibly impacted and f5.6 or faster with no visible impact.

With 24mp f16/f11 will almost become unusable, f8 visibly impacted and only f4 or faster with no visible impact. I don't think the majority of photogs has any interest in such a limitation....

Quite the opposite is true.   When viewed at the same image magnification, the image from a higher pixel density sensor will suffer from LESS diffraction effects, more more.

Hi Rick,

We are in perfect substantive agreement about the ins and outs of pixel counts and you are doing an excellent job in this thread of helping others understand how things actually stand.

However, for the benefit of those who have a less firm grasp about these matters than you and I, I would express what you say about diffraction in a slightly different way. To sort things out fully, I think it is appropriate to use a concrete example. Suppose we are comparing the performance of the same lens on cameras with different pixel counts, as Pekka Potka recently did with a Nikkor 35/1.4G on a D800 (36 MP) versus on a D700 (12 MP),


If we compare at the peak aperture of the lens, say about f/5.6 as in Potka's example, the difference is going to be pretty substantial. I don't know the numbers in this particular case (Potka shows test images rather than resolution numbers) but suppose it is 1000 lp/ih (line pairs per image height) at MTF-50 (50 percent contrast) for the D800 versus 700 lp/ih for the D700.

If we stop down further, say to f/16, both cameras will lose resolution due to diffraction. Again, I don't know the exact numbers, but the resolution figures might now be something like 800 for the D800 versus 600 for the D700. Based on these numbers, the D800 would lose more than the D700: 1000 - 800 = 200 versus 700 - 600 = 100. And in this sense, it is in fact correct to say that diffraction will have a stronger impact on the camera with higher pixel count than on the one with lower. However, and that's the really important point, the D800 will still be ahead of the D700. The resolution advantage of the D800 will be smaller and smaller as you continue to stop down beyond the peak aperture, but it will still have the advantage.

Very well put...summed it up perfectly!

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