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Re: [Phys-l] moon illusion measurement



I may be nuts but I have a sense that modern digital cameras are "smarter"
than old film based SLRs. I would love confirmation of my observation.

I went outside and focused my new digital camera on my mailbox from about 30
ft. The little focus box was on the mail box. I then turned about 15 degrees
to the right so the focus box was on a tree 100 yds down the street.

My hunch was that the camera would try to focus more on the tree and that
would change the sizes of other objects. Two tips of spruce trees side by
side down the block offer a nice reference. In one picture they are 3.0 mm
apart on the other they are 2.8 mm apart. Other distances are similarly
altered.

I am wondering if when you are focusing on the rising moon the camera has a
lot of terrestrial objects to confuse its focus (the heart of the illusion)
and when over head it sees only the moon and adjusts its focus to
accommodate.

An idea that needs corroboration.

Ken Fox

On Thu, Nov 5, 2009 at 6:02 AM, Michael Porter <listmoe@gmail.com> wrote:

If the pictures are digital, then the exposure information (including
focal length, etc.) might be encoded in the file. Also, how about
posting the pictures to flickr or something similar so we can take a
look at them?

Mike

---
Michael Porter
Colonel By Secondary School
Ottawa, Ontario, Canada

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