A very curious effect

Started Sep 21, 2010 | Discussions thread
osullis
Regular MemberPosts: 138
Like?
Re: A very curious effect
In reply to osullis, Sep 21, 2010

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

SOS

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!

SOS

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