A very curious effect

Started Sep 21, 2010 | Discussions thread
OP osullis Regular Member • Posts: 179
Re: A very curious effect

Sorry, I'm trying to delete this thread, but can't figure out how to do it!


osullis wrote:

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!


Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow