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Sony DSC-F717
 07/31/2003 08:59:28 PM · #1
Can being to close to a subject, a little dangerous to the focus factor?
I was trying to show a member that her camera could shoot closeup and found out that at about an inch away, I got a closer shot but not all of it was clear (Maybe the angle was wrong). At about 3 inches the suject was clear. Or, did I just change setting (angle) and didn't realize I did.
Also is it true that the closer the focus setting like 0.02meters the more critical or less tolerance there is for distance. Example: A thicker item the more of a chance, some of it will be less focused.
Any thoughts.
Canon EOS-40D
Canon EF 70-300mm f/4.5-5.6 DO IS USM
 07/31/2003 09:06:08 PM · #2
What you are describing is depth of field (DOF).

There are three factors that affect DOF.

1. Camera to subject distance (closer to subject, less DOF)
2. Aperture setting (larger aperture - smaller number, less DOF)
3. Focal length of the lense (longer focal length - more zoom, less DOF)

If you change any of these you change the amount of the image that will be in focus.

What you were experiencing in your demo was number 1.

Edit: I found the other thread on this

//www.dpchallenge.com/forum.php?action=read&FORUM_THREAD_ID=34608

Message edited by author 2003-07-31 21:13:14.
Sony DSC-F717
 07/31/2003 09:13:49 PM · #3
It may be.The angle may have played a part of the lack of focus.
the sbject was on the bottom half of the lense instead of the middle.

Message edited by author 2003-07-31 21:14:54.
Canon EOS-40D
Canon EF 70-300mm f/4.5-5.6 DO IS USM
 07/31/2003 09:22:56 PM · #4
You're absolutely right. The angle of view also plays a part here but it all comes down to the three things I mentioned. In your demo if the camera was angled downward (or upward) and not straight on then objects that are on the same horizontal or vertical plane will have a different relationship to the lense, some being closer and some being farther away.
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