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10-26-2013, 03:03 AM   #1
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K30 Autofocus Issue Live View vs. Viewfinder

Hi guys,

I just upgraded my K30 to firmware 1.05. During testing, I noticed autofocus is accurate through viewfinder, but back focus in liveview. Isn't it very strange? Isn't it liveview focus more accurate than viewfinder?? Why is it the other way around in my case? I will upload sample pics later.

Please share your idea.

Many thanks.

10-26-2013, 04:35 AM   #2
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Maybe its just focusing on the background because the background is more contrasty. Happens all the time, regardless of update.
Unless you are testing live view AF in the exact same conditions and its behaving differently, I would just go out into the real world and see how things work
10-26-2013, 04:41 AM   #3
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QuoteOriginally posted by ivanjiang Quote
During testing
How was this done? More information and images will help us figure out what your problem is.
10-26-2013, 05:35 AM   #4
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Please see test photos below:

All photos are taken with kit lens (18-55), manual mode, and all setting are remained same.

1. viewfinder, accurately focused


2. liveview, back focused a bit


10-26-2013, 05:47 AM   #5
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Please see test photos here

1. viewfinder, the one with blur background

2. Liveview, the one with clearer background
Attached Images
View Picture EXIF
PENTAX K-30  Photo 
View Picture EXIF
PENTAX K-30  Photo 
10-26-2013, 05:51 AM   #6
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There is no such thing as back focus in live view. If the camera isn't focusing properly, then either the af area is too large or there's not enough contrast in what you're trying to focus on.

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10-26-2013, 05:52 AM   #7
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Did you use a tripod and spot focus?

EDIT: The images seems cropped, please show the originals
10-26-2013, 06:05 AM   #8
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QuoteOriginally posted by altopiet Quote
Did you use a tripod and spot focus?

EDIT: The images seems cropped, please show the originals
No tripod, but placed on table, and spot focus.

10-26-2013, 06:06 AM   #9
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QuoteOriginally posted by Adam Quote
There is no such thing as back focus in live view. If the camera isn't focusing properly, then either the af area is too large or there's not enough contrast in what you're trying to focus on.
But isn't the photo taken via liveview is a bit out of focus? Is this normal?
10-26-2013, 06:49 AM   #10
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I would repeat the test. Do the live view shot first, then just switch to normal AF, while you press the shutter button, watch the lens focus ring, if it moves, it means the lens is either FF or BF, you can take it from there....







10-27-2013, 11:08 AM   #11
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In live view view when you choose the focus, how large is the square? I make mine as small as possible, so that it is more precise. Yes, those samples do confirm your story, but I would still suggest that you only bother "fixing" this if you notice problems during real world shooting.
10-27-2013, 12:11 PM   #12
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Are you sure the Liveview focus and the viewfinder focus are focusing on the same part of the image?

If you left it to auto selection of focus point then the two modes may be choosing different parts of the image to focus on.

You mention that you set it to 'spot focus' but is that in liveview (CDAF), in viewfinder mode (PDAF) or both? If in both did you then select the same point? It doen;t look like you selected the centre point because if you did then the lens cap would be in focus, not the USB drive. If you delected anything other than the centre point then it is quite possible that what you selected in PDAF is not the same as what you selected in CDAF.

Keep in mind that setting the focus point in one mode does not automatically set it to match in the other. Also, even if you set both to centre the live view focus (CDAF) usually picks a much larger areas than the viewfinder mode.
10-28-2013, 06:54 AM   #13
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Thanks for your inputs. My test was done using the same setting, spot focus in both modes, and the point was on the USB disk.

I have done another test with another 55-200 lens, the problem doesn't exist. I guess it is because of the lens, it might be a bit old.
10-28-2013, 04:41 PM   #14
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make sure AF-A and Expanded Area AF are unselected in menu prior to test. And make sure you use the same widest aperture for both.
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