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08-25-2009, 11:25 AM   #1
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AF and wide angle lenses

i've noticed from all my pentax bodies DL, K10, K2000 that using the AF with a wide angle lens is a lot of times a hit-or-miss proposition.

not to blame the lens or the camera, but wide angle lenses do pose some challenges to the camera's AF specially at farther distances.

i read this article and it sort of makes sense,
Mastering Wide-Angle

would you masters of the wide-angle lens share your AF technique ?
of course MF is an option, but i'd like to hear how you coax your AF to do it right, at least for most of the times.

tnx

jordan
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08-25-2009, 11:33 AM   #2
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The tips on that article are quite spot-on.

I'm hardly experienced enough to have a fail-safe technique, although I have noticed at times AF locking in at around 2-3m when I wanted it to focus on something at infinity - in those cases, I can usually see in the viewfinder that the image is not completely in focus, so I just retry AF and it usually locks on properly then.
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08-25-2009, 12:51 PM   #3
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Originally Posted by Ash View Post
The tips on that article are quite spot-on.

I'm hardly experienced enough to have a fail-safe technique, although I have noticed at times AF locking in at around 2-3m when I wanted it to focus on something at infinity - in those cases, I can usually see in the viewfinder that the image is not completely in focus, so I just retry AF and it usually locks on properly then.
Yep. i notice that my camera's AF also locks in at objects within 1-2 meter and fails to re-focus on objects at further distances. sometimes i forget cause i'm in a hurry to take the shot, and of course, result is a blurred image.

guess this is a limit to the camera's AF mechanism.

i'm also not sure how accurate is the distance markings on the lens. i think i would just disregard what the markings indicate and go for the visual confirmation on the focusing screen.
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08-25-2009, 01:13 PM   #4
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I rarely let the camera choose the focus point; instead, I'm normally using either center or specifying the focus point with the buttons.

If you have something not in focus, it generally ends up being user error at that point...
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08-25-2009, 01:31 PM   #5
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Just be proactive with the focusing, either quick shift or refocus, to get the right result.
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08-25-2009, 01:59 PM   #6
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Originally Posted by legacyb4 View Post
I rarely let the camera choose the focus point; instead, I'm normally using either center or specifying the focus point with the buttons.

If you have something not in focus, it generally ends up being user error at that point...
i always use center point only. but sometimes with wide angle lenses, the camera refuses to refocus after pointing the cam to a different object at a different distance. i put my hand in front to throw the focus off and force it to re-focus.

that article that i linked to explains it best.
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