At 18 MP the Canon 60D should be diffraction limited to red light at
f/5.6 or green at about f/7.1. Blue doesn't get hit until about f/9-10
but there's little blue in your image. At f/16 the diffraction limits
are 2 MP for red, 3 MP for green and 6 MP for blue.
I'm going to guess that the height of the full image is roughly 2" which
would make the distance from image plane to subject at 135mm about 18".
Getting a depth of field of even 1/2" at that distance, aperture and
focal length implies a resolution limit of about 0.6 MP for the entire
image.
There's nothing wrong with the image. It looks very good. But the
resolving power of the sensor isn't being taxed at all. You're just not
aware of how much detail has not been recorded.
If you were to shoot a flat, high resolution target (to get rid of the
DOF effect) at f/5.6 and again at f/16 you'd see it.
Chuck Norcutt
On 6/14/2011 1:50 AM, Moose wrote:
> On 6/13/2011 10:16 PM, Chris Barker wrote:
>> That's very bold, Moose.
>
> It does stand right up and demand attention!
>
>> F16 seems to be the way to capture focus of almost all a subject like that.
>
> Chuck keeps telling me that f16 is starting off the edge of diffraction
> softening on FF. So here on a smaller sensor, it
> 'should' be a problem. But I've tried a few comparison shots at this sort of
> close-up distance. On this camera with this
> lens, f16 doesn't seem to lose any detail I can see, while I gain DOF.
>
> The DOF you are seeing isn't the whole story, as it's a considerable crop.
> The whole flower does start going OOF at the
> margins toward the camera.
> <http://galleries.moosemystic.net/MooseFoto/index.php?gallery=Home/Garden_June_2011&image=_MG_1917.jpg>
>
> Moose
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