A very good video on "diffraction" and sharpness

[Manfred M]

Would it be fair to opine that, as they use only the sweet spot of the lens, a crop sensor camera
is less susceptible to diffraction than is a full frame camera.

No, diffraction is related to the size of the aperture that is being used, the smaller the aperture, the more that diffraction becomes an issue. Light passing through a small aperture is affected by the opening and interference patterns are set up. So a crop-frame and full frame lens of the same focal length, set to the same aperture opening will show identical diffraction issues.

[Stagecoach]

Very interesting video, but... shouldn't this kind of comparisons be made by taking pictures of test charts with lines placed at different intervals (eg the ones used for MTF charts) instead of taking pictures of trees ?. IMHO the effect of diffraction would be quite more evident and could be even measured and assigned a numerical value (sorry, I'm engineer...)

Joan,

As an engineer and a photographer I find it far more interesting to see examples/comparisons of real world situations that could be applicable to what I actually do with regard to the affects of diffraction.

It's scenery with trees and detail I'm shooting in the field, not charts.

Just another perspective

[Manfred M]

Joan,

As an engineer and a photographer I find it far more interesting to see examples/comparisons of real world situations that could be applicable to what I actually do with regard to the affects of diffraction.

It's scenery with trees and detail I'm shooting in the field, not charts.

Just another perspective

+1

The theory is nice and looking at charts is fine, but neither end up impacting the camera settings I select to get the shot I'm after.

Another engineer & photographer...

[george013]

No, diffraction is related to the size of the aperture that is being used, the smaller the aperture, the more that diffraction becomes an issue. Light passing through a small aperture is affected by the opening and interference patterns are set up. So a crop-frame and full frame lens of the same focal length, set to the same aperture opening will show identical diffraction issues.

I think this is a misunderstanding. Diffraction itself is caused by light passing an object. If that object is an aperture, then that diffracted border of that lightcone creates an Airy disk. The size of that Airy disk is depending on the top-angle of that light cone. The light-cone itself is based on the aperture diameter and the image-distance. Only with focus at infinity the focal plane and image plane are the same.
With a same F-number the diameter of the aperture of a 200mm lens is 4 times of a 50mm lens but the top-angle of the light-cone is the same, and the Airy-disk is the same. Off course when focused at infinity.

George

[ajohnw]

What do you mean with a difrraction limited camera lens?
George

A camera lens that will actually produce a true diffraction spot from a point source rather than a larger circle of confusion, often much larger in practice. A typical point source is a star - they are big but rather far away and are the nearest thing we can get to one. Theoretical resolution is based on the idea that an object with a physical size is made up of an infinite number of point sources.

John
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[george013]

A camera lens that will actually produce a true diffraction spot from a point source rather than a larger circle of confusion, often much larger in practice. A typical point source is a star - they are big but rather far away and are the nearest thing we can get to one. Theoretical resolution is based on the idea that an object with a physical size is made up of an infinite number of point sources.

John
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To me diffraction is a physical phenomenon, light passing an object is disturbed. In the world of photography etc. this results in an Airy disk. And that Airy disk may bother you or not, it is there.
The circle of confusion is not a physical phenomenon, it's more mathematic, calculating backwards what you experience as being sharp under certain circumstances.
That brings me to the next question: what is a true diffraction spot?

George