Details, DP2M and Pixel-Peeping ...

Started 2 months ago | Discussions thread
xpatUSA
OP xpatUSA Forum Pro • Posts: 15,549
Re: Way back when...

docmaas wrote:

The sd9 was still new and exciting Troy Ammons posted a pic of a fly fisherman casting somewhere in Florida. He calculated that the gauge of the flyline should have been one pixel in his image and the curve of the line was fully visible.

If he was right, I never checked his calculations, that would indicate that a single pixel or a string of them could be seen if the background against which they appear is sufficiently different and I suspect somewhat uniform.

Yes, Mike, the best example around here is sunlit barbed wire against a shadowy wooded background. Also dried grass stalks, but with somewhat lesser contrast. Say 3mm wide. At 20 meters, that's about I pixel on a DP2M. However, an object doesn't suddenly disappear ** in a DP2M shot if it gets thinner than exactly one pixel. On the other hand, dark objects (e.g. bare tree twigs) can start to fade away against the sky due to lens veiling flare.

I look at unsmoothed pixellation all the time when comparing images from different cameras and find it very meaningful.

Quite so. Not quite the same thing but, if an edge or grass stalk is NOT pixelated (i.e. jaggies), then I suspect poor focusing or camera/object  movement.

<> What I am usually looking for is how much distinction one sees between a set of pixellated blocks in one image vs another. The granules (not pixels) but blocks of color making up the image at different magnifications can have smaller and larger numbers of shades and degrees of gradation and the more they do generally the better the image appears at normal sizes ...

Makes sense to me.

... unless of course the source of the granulation is some kind of noise but then I don't look at noisy photos. If I did it would be because I was looking for information about noise.

** any more than diffraction suddenly "sets in" at some f-number - as we read so often in lens reviews ...

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Ted

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