Originally posted by VoiceOfReason just to find I was shooting myself in the foot.

Nice try but you actually shoot yourself into the foot quite successfully

You are asking secondary questions and Class A's correct answers may not have made you notice. Let me try to expain ...

What you try to achieve are gallery-quality prints. Well, after you managed the artistic part of this challenge which means sharpness may not matter so much anymore. But ignoring this for a second and talking about sharpness.

The easiest way to look at sharpness is that there are many sources for blur and they all add up in the final image. It is not normally taught in a coherent way though. I will avoid the math here, just introduce the general concept. You find all the math and how it relates to mtf (whatever that shall mean) in my blog. Below, I quote some numbers, but the mathematical details are over-simplified. I quote them for make interested readers understand, not to provide means to compute sharpness.

So, let me introduce blur from a particular source as "b" which shall denote a blur spot diameter. Where the blur spot shall denote the image created by a single point-shaped light source. So, ideally, b=0. Also, think of b as sort of inverse resolution.

The overall blur results from adding up all blur terms b. Think of taking the sum. The true math is much more complicated though, more complicated than taking the RMS (ignore this sentence).

So, blur from pixellation may be characterized by something like b= 5 Micron, which shall be the pixel size. Obviously, this number is somewhat smaller for a 24MP camera than a 16MP camera (about 1 Micron smaller). All other blur is unrelated to MP.

Another blur is defocus. Which is about 20 Micron at the limit of deoth of field for an APSC camera.

Another blur is from lens aberration. Which can be very small, like 5 Micron / N where N is the F-stop number. Which obviously can become as small as 1 Micron. But only for a few famous prime lenses and in the image center. It is much larger in general.

Another blur is from the Bayer-anti alias filter. It creates a bit less additional blur than from pixellation above.

Another blur is from shake. And yet another from subject motion. Both are computable.

Yet another blur is from noise. However, noise does affect point blur much more than line blur and it is best to treat noise as remaining artefact size after noise reduction. Again, say a few Microns depending on ISO.

And then there is blur from diffraction. It is about 0.33 Micron * N where N is the F-stop number again. So, at F15, it is roughly 15/3 or 5 Microns which happens to be the Raleigh limit of diffraction for a sensor with 5 Microns pixel pitch. I've choosen the numbers such that diffraction causes blur as large as a pixel at the Raleigh limit. Again, a useful simplification for easier understanding: Divide the F-Stop by three abd if the resulting number is smaller than the pixel pitch in Micron then you can still resolve detail at the pixel level. Beyound, no. Obviously though, diffraction always creates blur at any aperture and now you got a feeling for it.

And now for the trick ...

In order to create a very sharp image, you have to *BALANCE* all blur terms to become roughly equally large!

This is why experience matters so much. You won't be able to compute it as it is too complex to be done in the field. The camera firmware could help you but for some reaon, firmware authors aren't that innovative...

But why is it so?

Because the different blur terms counteract each other: lens aberration counteracts diffraction (look at the terms: /N and *N, so, you must select N in between to take both effects into account). Shake and motion abd defocus counteracts noise, and so on ...

Everything considered, you see that a possible higher MP number in the K-3 cannot but help. But only in the regime where all blur terms combined are down to a few Microns already. Which is not the case for a majority of images. But it won't never hurt.

Note to fellow photographers: Why always point to other sites? I think it is better to understand than to cite.

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Last edited by falconeye; 06-22-2013 at 10:38 AM.
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