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03-02-2014, 02:20 PM   #1
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malenisjaj's Avatar

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MF vs AF vs Liveview - focus indicator issue?!

Hi,

I've done some test with couple of lenses. SMC 135mm f2.5, SMC 200mm f4.0, SMC-A 35-105mm f3.5 and SMC-DA 18-55mm f3.5-5.6. All focusing was manually except when I was using SMC-DA. Test was indoors, distance from the subject was from 50cm to 200cm (depending on the lens) with infrared remote (3s delay) and the pictures (croped@100%) you'll see are center of all images. Camera, K-5 II on tripod.
Bottom line, it seems that focus indicator is not indicating exactly when the subject is in focus.

1. First, SMC 135@f/2.5. Distance, about 1.5m.
The first part of the image is when I let the focus indicator to inform me when the subject is in focus. The second and the third one is when I used LiveView and/or viewfinder but I didn't let focus indicator to set the images. I relied on my eye(s). First two are out of focus.

2. SMC 200mm. Distance, 2.1m. First image (f/4) and the second one (f number after f/4) where shoot when focus indicator informed me that the object is in focus. Third ((f/4) and fourth (f number after f/4) were shoot using liveview and/or viewfinder but here, I relied on my eyes. Here, it seems that focus indicator is good.

3. SMC-A 35-105 @105mm f/3.5 Distance around 1.5m. I did the same as on the image above: first and second image shooted when focus indicator informed me to do that and the third and fourth without relying on the focus indicator. Again, first two are not in focus.

4. SMC-DA 18-55 @55mm f/5.6. Distance around 50cm. First one is shoot with relying on focus indicator (AF on) and second one without (AF off). Out of focus is obvious.

Now, I didn't run test outside (maybe tomorow I will) but I'm asking my self, is this "normal" or my camera is not?
Does anyone there with more expirience can tell me what to do?

Kind regards,

03-02-2014, 02:58 PM   #2
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fgaudet's Avatar

Join Date: Oct 2013
Location: Ontario
Posts: 726
There is no actual data (that I could find) that state the "size" of the area covered by each little red focus square. I know for a fact that it is much bigger than the size of the square is in the VF is. So it might confirm focus, show the little square wherever it focused on but it might be locked to anything round the edge of the little square. With your older lens, set your object at an exact distance from your sensor (like 2m, use the marking on the camera) and see on the scale on the lens when you get focus confirm

In manual I found that the focus confirm was not all that great. The area IS in focus somewhat but it definitely needs some tweaking. Trust your eyes, not your camera. If you find the VF too small (or not practical) use LV to focus, in LV if you hit "info" it will zoom in, making focussing much easier. This is how I focus for macro or most shot when on tripod.

I would say that this is "normal", every DSLR I owned behaved like this, not only my Pentax.

But looking at your pictures, your out-of-focus samples are not too far off, not in perfect focus but most of them are well within normal AF (or focus confirm) accuracy, considering the distance
03-02-2014, 03:07 PM   #3
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QuoteOriginally posted by malenisjaj Quote
Hi,

I've done some test with couple of lenses. SMC 135mm f2.5, SMC 200mm f4.0, SMC-A 35-105mm f3.5 and SMC-DA 18-55mm f3.5-5.6. All focusing was manually except when I was using SMC-DA. Test was indoors, distance from the subject was from 50cm to 200cm (depending on the lens) with infrared remote (3s delay) and the pictures (croped@100%) you'll see are center of all images. Camera, K-5 II on tripod.
Bottom line, it seems that focus indicator is not indicating exactly when the subject is in focus.

1. First, SMC 135@f/2.5. Distance, about 1.5m.
The first part of the image is when I let the focus indicator to inform me when the subject is in focus. The second and the third one is when I used LiveView and/or viewfinder but I didn't let focus indicator to set the images. I relied on my eye(s). First two are out of focus.

2. SMC 200mm. Distance, 2.1m. First image (f/4) and the second one (f number after f/4) where shoot when focus indicator informed me that the object is in focus. Third ((f/4) and fourth (f number after f/4) were shoot using liveview and/or viewfinder but here, I relied on my eyes. Here, it seems that focus indicator is good.

3. SMC-A 35-105 @105mm f/3.5 Distance around 1.5m. I did the same as on the image above: first and second image shooted when focus indicator informed me to do that and the third and fourth without relying on the focus indicator. Again, first two are not in focus.

4. SMC-DA 18-55 @55mm f/5.6. Distance around 50cm. First one is shoot with relying on focus indicator (AF on) and second one without (AF off). Out of focus is obvious.

Now, I didn't run test outside (maybe tomorow I will) but I'm asking my self, is this "normal" or my camera is not?
Does anyone there with more expirience can tell me what to do?

Kind regards,
The K-5 II isn't exactly know for stellar performance in live view. Still, cameras can make mistakes, especially and low light and when there's little contrast.

Adam
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