« on: November 25, 2012, 06:11:22 PM »
If you crop just the tower from both images, and view them at the same size on the screen, they will look identical. That means the blur is identical.Thx for the link - there is deep explanation we all agree with (I suppose).
Examples from http://toothwalker.org/optics/dof.html.
The car to the right of the subject has more blur with the 100mm lens than with the 28mm lens, right?
Wrong. Same blur. That's the case even in your extreme example.
I'm not saying it looks the same, the tower and car do look more blurred with the longer focal lengths. Like I said, it's good illusion.
And our different view on the last posts is nicely summed up by paragraph:
This is true when we speak of the absolute blur. The absolute blur is given by the blur disk diameter of a point in the background, such as the highlight reflections off the cars in the street. However, when we speak of the relative blur we must relate the blur disk size to the "image magnification" of the background. And that magnification is larger with the 100-mm lens too. As a matter of fact, the relative blur of the backgrounds is identical.