16-45mm not behaving itself?
Posted 03/02/2011 - 16:34
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Isn't that just a DOF effect? (Seeing that the foreground is sharp, and the hill is quite a distance away).
Best regards
Terry
K20D, Optio I10, DA 18-55 1:3.5-5.6 AL II, A 1:1.7/50, D FA 1:2.8/100 Macro, Sigma 70-300 1:4-5.6 APO DG Macro, Pentax AF 360FGZ
Terry
K20D, Optio I10, DA 18-55 1:3.5-5.6 AL II, A 1:1.7/50, D FA 1:2.8/100 Macro, Sigma 70-300 1:4-5.6 APO DG Macro, Pentax AF 360FGZ
Posted 03/02/2011 - 18:15
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The exif page is here: link
Unsurprisingly it's f8... my default aperture setting!
I take your point about DOF effects, as the focus is on the shore, not the hill... but the blurring seemed strange, not like the normal OOF effect. And it seems worse at the top on the left hand side than on the more distant cliffs on the middle right. Perhaps the DOF effects are exacerbating some problem with the lens?
The focus is further back in this one (warning full size): link, and you can see that the more distant parts of the hill on the right hand side are much sharper than the parts of the hill at the top of the frame,.
Unsurprisingly it's f8... my default aperture setting!
I take your point about DOF effects, as the focus is on the shore, not the hill... but the blurring seemed strange, not like the normal OOF effect. And it seems worse at the top on the left hand side than on the more distant cliffs on the middle right. Perhaps the DOF effects are exacerbating some problem with the lens?
The focus is further back in this one (warning full size): link, and you can see that the more distant parts of the hill on the right hand side are much sharper than the parts of the hill at the top of the frame,.
Posted 03/02/2011 - 18:28
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Possibly slight rotational movement of the camera during the exposure, hence the smearing. Even at 1/250s it is possible to get camera shake.
You can onkly really judge with the camera on a tripod and only then if the 2 second timer or a cable release are used.
You can onkly really judge with the camera on a tripod and only then if the 2 second timer or a cable release are used.
Best regards, John
Posted 03/02/2011 - 18:38
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If you were focussed at the lens's minimum focussing distance, even at f8, you would only have 1.98M of critical sharpness. The ideal would have been to select a focussing point 1/3 of the way in.
Then I followed your link to the larger image and agree that the effect is very strange. Has the lens received a knock, could something be out of alignment?
It looks to me like chomatic aberration, although that lens is prone to it wide open I wouldn't have expected it at f8.
Worth shooting something with similar conditions at all four corners I think.
Then I followed your link to the larger image and agree that the effect is very strange. Has the lens received a knock, could something be out of alignment?
It looks to me like chomatic aberration, although that lens is prone to it wide open I wouldn't have expected it at f8.
Worth shooting something with similar conditions at all four corners I think.
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -
Posted 03/02/2011 - 18:40
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Just seen John's post and agree with that too. It needs further investigation.
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -
Posted 03/02/2011 - 18:54
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Thanks John, I didn't think about camera movement. I'll try some tripod mounted shots at various settings and see what's up.
Cheers Ken. Yes, chromatic aberration is what it looks like, and not the crisp purple type which you normally get with this lens.
The lens was second hand (from the forum) so I can't know that it hasn't received a knock at some point. I am suspicious of the slight wobble the lens barrel is subject to when extended at 16mm. Perhaps when the camera is held a certain way - in this case portrait format - the lens elements aren't aligned quite right. I don't get the same result in landscape format.
Another large size portrait image - look at the tops of the TV aerials: link
Cheers Ken. Yes, chromatic aberration is what it looks like, and not the crisp purple type which you normally get with this lens.
The lens was second hand (from the forum) so I can't know that it hasn't received a knock at some point. I am suspicious of the slight wobble the lens barrel is subject to when extended at 16mm. Perhaps when the camera is held a certain way - in this case portrait format - the lens elements aren't aligned quite right. I don't get the same result in landscape format.
Another large size portrait image - look at the tops of the TV aerials: link
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