Focussing in Live View
Posted 23/11/2013 - 10:06 - Helpful Comment
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To an extent what you describe is 'normal'. The contrast-detect AF system in live view is by design slower than the system used during viewfinder operation. It will be worse on flat surfaces or areas of the same tones.
Try moving the square around using the 4-way controller first and place it over your subject, aiming for a spot that has a noticeable edge. This should increase the speed of focus 'capture'.
If you're finding it does not work well enough for you, you can switch the live view AF mode to 'phase detect' (using a menu item setting). This will set the camera to use the dedicated AF sensors below the pentaprism and will be fast and accurate. The only issue is that to do this requires the mirror to flip back down for the light to be passed to the sensors - so the live view image will 'black out' for a second. But when it restores you should be nicely focused.
For this approach its probably best to keep the focusing and shutter operations separate, so you are sure you've got focus before capture. So maybe using the rear AF button would be helpful - press this for the focusing process, then once you're happy use the shutter button to take the picture. Again, this can be controlled by the menu items.
Try moving the square around using the 4-way controller first and place it over your subject, aiming for a spot that has a noticeable edge. This should increase the speed of focus 'capture'.
If you're finding it does not work well enough for you, you can switch the live view AF mode to 'phase detect' (using a menu item setting). This will set the camera to use the dedicated AF sensors below the pentaprism and will be fast and accurate. The only issue is that to do this requires the mirror to flip back down for the light to be passed to the sensors - so the live view image will 'black out' for a second. But when it restores you should be nicely focused.
For this approach its probably best to keep the focusing and shutter operations separate, so you are sure you've got focus before capture. So maybe using the rear AF button would be helpful - press this for the focusing process, then once you're happy use the shutter button to take the picture. Again, this can be controlled by the menu items.
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Posted 23/11/2013 - 11:43
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Brilliant...thanks for that. (A true case of RTFM - Read The 'Flaming' Manual!). I waded through the Manual but not so good and now see there is a good section on this in a great book by Yvon Bourque - "Everything you need to know and then some" (It does what it says on the cover!)
I tried the Contrast and AF Mode and both improved for sure it seems strange that the default is 'Face Recognition'.. the Contrast struggled on one test (and actually failed to produce a focused image where the Phase Difference method scored every time (but as you elegantly described the screen blanks out initially).
On to the next 'challenge'!
I tried the Contrast and AF Mode and both improved for sure it seems strange that the default is 'Face Recognition'.. the Contrast struggled on one test (and actually failed to produce a focused image where the Phase Difference method scored every time (but as you elegantly described the screen blanks out initially).
On to the next 'challenge'!
'Life looks simple through a viewfinder'.....then I went Digital!
Keith
K3 III, DA* 16-50, HD DA 16-85, DA* 50-135, DA* 300, HD 55-300 PLM, HD 1.4x, AF360
Keith
K3 III, DA* 16-50, HD DA 16-85, DA* 50-135, DA* 300, HD 55-300 PLM, HD 1.4x, AF360
Posted 23/11/2013 - 19:30
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Snappyhoffy wrote:
Starting to get into my recently purchased K5 after upgrading from K10D. So far so good!
One thing that seems to be strange is when using the camera in Live View mode the focussing seems to be really wired. With a Pentax 18-250 zoom it is reasonably quick in 'normal' TTL mode but when you switch the system seems to go to great extremes to focus in and out before finally finding the 'sweet spot'. Is this normal?
I have upgraded firmware to the latest and it is a K5 not K5II
Yes it's normal. Contrast AF through the sensor can't determine whether the subject is out of focus front or back so takes a lot longer as there's soem trial anderror involved.Starting to get into my recently purchased K5 after upgrading from K10D. So far so good!
One thing that seems to be strange is when using the camera in Live View mode the focussing seems to be really wired. With a Pentax 18-250 zoom it is reasonably quick in 'normal' TTL mode but when you switch the system seems to go to great extremes to focus in and out before finally finding the 'sweet spot'. Is this normal?
I have upgraded firmware to the latest and it is a K5 not K5II
These two pages explain the differences between the two methods excellently!
http://graphics.stanford.edu/courses/cs178/applets/autofocusPD.html
http://graphics.stanford.edu/courses/cs178/applets/autofocusCD.html
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Flash: AF-540FGZ, Vivitar 283
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98 posts
19 years
Buckinghamshire,
UK
One thing that seems to be strange is when using the camera in Live View mode the focussing seems to be really wired. With a Pentax 18-250 zoom it is reasonably quick in 'normal' TTL mode but when you switch the system seems to go to great extremes to focus in and out before finally finding the 'sweet spot'. Is this normal?
I have upgraded firmware to the latest and it is a K5 not K5II
Keith
K3 III, DA* 16-50, HD DA 16-85, DA* 50-135, DA* 300, HD 55-300 PLM, HD 1.4x, AF360