Curious aperture effect
See below for several photos of bricks taken through a circular hole in a board. I was stationary and did not adjust the focal range -- stayed at 125 mm. The only thing I changed was the aperture. As you can see, I began at 2.8 and stopped down a full stop until getting to f/16.
Here's what's not surprising: the focal plane grew wider as I stopped down. No mystery there. The borders of the hole is increasingly blurry as I opened the aperture up.
What IS surprising: it appears that the diameter of the circle shrinks as I stop down the lens. Why does this happen when I don't move closer or zoom in?
Zooming compresses things that are at different distances, but this effect does not appear to explain this particular phenomena.
Explanations are welcome!
|Dirt Hose by poppyjk|
|European bee-eaters by drvanger|
from A Big Year - birds
|Fat Is Beautiful Guinea 2008 DP by MarioSS|
from - Fat is Beautiful - (Woman's Portrait n Black and White+ A Border)