Diffraction Effects (Example Photos)

Started Nov 27, 2011 | Discussions thread
James Bligh Senior Member • Posts: 1,855
Re: different distances lights travel through cancels away different diverging angles

AV Janus wrote:

But since it depends from the size of the hole the light passes through, wouldn't it be also dependent on focal length of the used lens?

Is f8.0 aperture on 24mm the same diameter as f.80 on 135mm lens?

If you see the diffraction limit calculator there is no variable such as different focal length lens type, instead it has a variable of Camera Type.


I am not a physicist, but I guess why this way. Parallel light rays which pass through a small aperture begin to diverge. Diverging angle will be steeper in F8 of 24mm compared with F8 of 135 mm. But the diaphragm of longer focal length lens is far from the imaging surface (sensor) compared with that of short focal length lens. So the different distances lights travel through aperture holes cancels away different diverging angles and the circle of divergence of rays in the imaging surface (sensor) will be same between different focal length lenses in same F number.

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