Why does Pentax autofocus seem more accurate in AUTO AF-point mode than in SEL mode?
Asked 12/9/2011
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2 answers
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On Pentax bodies like the K10D and K-5, I’ve noticed autofocus looks more accurate in AUTO AF-point mode than when I manually choose a focus point in SEL mode. In AUTO mode, images often come out very sharp, and sometimes two AF points light up in the viewfinder. In SEL mode, using a chosen point on the same kinds of shots, focus can look a bit softer or slightly off.
Why would AUTO mode appear more accurate than SEL mode, and what does it mean when multiple AF points light up?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
6
SEL or Select mode is a Pentax focus mode that allows you to select which point to focus on out of the available focus points. Auto mode is on the other hand going to select from the available focus points(11 in the case of the K10D) whichever it feels is the best using the TTL phase-matching system(SAFOX VIII) and the subject. A third option is available named center, and all it does is select the center AF point.
As far as I know, the Pentax K10D does not use any type of area AF system. With that said, if you did see multiple focus points light up, it is probably just telling you that they are both in focus currently. SEL mode is only really activating one focus point at a time, so it is assumed the rest are turned off and will not light up at all under that mode.
If performance is truly different as in "missed shots" while not moving the camera or subject, but just by flipping the focus mode, then you have a issue that should be looked at by a Pentax repair center.
To resolve your issue, simply select AUTO when you want all points to be active, and SEL when you want to select a single point outside of the center(use center for that).
Originally by user4892. Source · Licensed CC BY-SA 4.0
user4892
14y ago
0
Generated from our catalog & community — verify before relying on it.
AUTO and SEL work differently. In SEL mode, the camera uses only the single AF point you chose. In AUTO mode, the camera evaluates all available AF points and picks the one(s) that see the strongest usable focus target, usually something with good contrast.
So AUTO can seem “more accurate” because the camera may be choosing a better target than the one you intended. In SEL mode, if your selected point is over a lower-contrast area, or if the AF sensor’s true coverage doesn’t match the small red mark exactly, focus may land slightly differently than expected.
Also, the AF sensing area is typically larger than the red indicator dot in the viewfinder and may not align perfectly with it. That can make manually selected-point AF seem less precise even when the camera is working normally.
If multiple points light up in AUTO mode, that usually indicates more than one point has achieved focus, not that SEL mode is using multiple points together.
If you want predictable placement, use SEL or center point and aim at a high-contrast detail. If you want the camera to choose the easiest subject to lock onto, AUTO may give more consistently sharp-looking results.
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AI14y ago
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