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11-13-2011, 10:03 PM   #1
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Does my 55-300 have a focussing issue ? [img]


1/400 ISO 250 F5.8 300mm

Looks like the area behind the sea gull is focussed while the sea gull itself is soft.

[ Overview ]
Creation date: 11/12/2011 17:20
Camera: PENTAX K-x
Lens: smc PENTAX-DA L 55-300mm F4-5.8 ED
Focal length: 300 mm (equiv. 450 mm)
Aperture: F5.8
Exposure time: 1/400"
ISO speed rating: 250/25
Program: Aperture Priority
Metering Mode: Pattern
White Balance: Auto
Focus Mode: AF-S
Image Stabilizer: stabilized
Noise Reduction: Off
Flash: Flash did not fire, compulsory flash mode


Last edited by photoleet; 11-13-2011 at 10:49 PM.
11-13-2011, 10:13 PM   #2
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Which focusing point was used? You should include the full exif as well.

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11-13-2011, 10:48 PM   #3
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QuoteOriginally posted by Adam Quote
Which focusing point was used? You should include the full exif as well.
Multi-Segment

[ Overview ]
Creation date: 11/12/2011 17:20
Camera: PENTAX K-x
Lens: smc PENTAX-DA L 55-300mm F4-5.8 ED
Focal length: 300 mm (equiv. 450 mm)
Aperture: F5.8
Exposure time: 1/400"
ISO speed rating: 250/25
Program: Aperture Priority
Metering Mode: Pattern
White Balance: Auto
Focus Mode: AF-S
Image Stabilizer: stabilized
Noise Reduction: Off
Flash: Flash did not fire, compulsory flash mode
11-14-2011, 12:12 AM   #4
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Look at the ground. It,s pretty clear the sand directly under rightmost bird's tail is in focus. Meaning the camera simply chose to focus on the tail. Not sure where you wanted it to focus or what steps you took to communicate this desite to the camera, but on the face of it, choosing to focus on a bird's tail is not indicative of any sort of problem.

11-14-2011, 06:20 AM   #5
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QuoteOriginally posted by Marc Sabatella Quote
Look at the ground. It,s pretty clear the sand directly under rightmost bird's tail is in focus. Meaning the camera simply chose to focus on the tail. Not sure where you wanted it to focus or what steps you took to communicate this desite to the camera, but on the face of it, choosing to focus on a bird's tail is not indicative of any sort of problem.
But the thing is that a lot more of sand in front of bird tail is in focus, I know I didn't focus on the tail.
11-14-2011, 10:59 AM   #6
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QuoteOriginally posted by Adam Quote
Which focusing point was used?
QuoteOriginally posted by StDevious Quote
Multi-Segment
Multi-segment is a metering method, not a focus point. Are you using center point and recompose, selecting the AF point yourself, or are you using auto-select (camera chooses focal point)?

You can't determine whether there is a problem with AF from one photo. You need to do some specific testing.
11-14-2011, 11:29 AM   #7
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QuoteOriginally posted by audiobomber Quote
Multi-segment is a metering method, not a focus point. Are you using center point and recompose, selecting the AF point yourself, or are you using auto-select (camera chooses focal point)?

You can't determine whether there is a problem with AF from one photo. You need to do some specific testing.
My bad, yes center point and recompose
11-17-2011, 12:23 AM   #8
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QuoteOriginally posted by StDevious Quote
But the thing is that a lot more of sand in front of bird tail is in focus
Not really. The sand shows the tip of the tail to be smack dab in he middle of the focus zone.

QuoteQuote:
I know I didn't focus on the tail.
Not on purpose, but the camera can,t read minds, assuming you pointed the focus point somewhere on that bird, the tial wold have been in range of the focus sensor. The focus sensors are too broad to allow the kimd of pinpoint precision that would be needed to be able to pick a particular part of the bird to focus on. Plus, focus recompose, while useful, does potentially shift the focus point a bit (Foogle the phrase "focus recompose sucks", but realize he ocerstates the case by a huge margin).

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