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06-02-2012, 05:18 AM   #1
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K-r : Live View focus, AF & manual

I am fairly new to Live View, as I had been shooting with the K200D for 4 years which did not feature it. My mother has that camera now, and I have a K-r.

I am having a few issues with live view .

1) AF in Live view mode.

With the K-r, I have noticed that the AF is extremely slow in live view. With my 50mm/1.7, starting with the focus ring on infinity, I have seen it turn the focus ring 3 times, and take 3 seconds to focus at a distance of about 12ft.

In low light, it's not just slow. Not only does it turn 3 times, it ends focusing completely wrong - at 45cm . It just never achieves proper focus no matter how I try.

I had to read the manual to figure out that the AF method can be changed to Phase Difference for Liveview. But then Liveview is interrupted. However, it works far better. The Face Detection and Contrast Difference methods for Liveview AF are just too slow and inaccurate. What's even more confusing is that in Auto mode, it defaults to Face detection and cannot be changed ! And that performs really poorly in low light. A few weeks ago when I first got the camera, I decided to use Liveview in a dark restaurant. Every single picture was out of focus Even the few that I tried to take with flash, before the restaurant owner told us to stop. And my partner was extremely upset at the green AF assist lamp light in his face for so long, too ! All for naught - I never got him in focus at all !.

This seems to be an algorithm issue with the Face Detection and Contract Difference.
I am surprised that the problem happened even with my fastest AF lens, the Pentax-F 50mm/1.7.
I just tried to raise the ISO, thinking it might help the AF Liveview, but the accuracy did not improve - still wrong focus. My default auto ISO is up to 1600. But even at ISO 25600 it still couldn't AF correctly.

Once I turned all the lights on, then Liveview finally did AF correctly, though slowly. But improving the lighting before focusing is not an option in most situations.

I must now remember never to use Liveview with green mode indoors. My favorite mode is actually "no flash" auto mode, and for that it's possible to switch Liveview AF to Phase difference. It's still very disconcerting to see the Live view "die" once the camera switches to Phase difference. The screen goes completely black. I wish it retained the last (frozen) picture while the camera focused, instead.

If it makes anyone feel better, my Canon T3i with 18-55 IS II lens at 55mm isn't any better in the same test. Liveview AF is even slower, and also inaccurate. The AF makes a different mistake, it's not as much off. I can't tell how much exactly since the lens doesn't have any indication of distance on the focus ring. But the focus is still wrong. AF is achieved correctly at 18mm, though.

The Canon does let you switch to AF "quick mode" even for auto (green), though.

2) Manual focus in Live View mode.

I want to use Live view for manually focusing. This is especially the case when using my 800mm mirror lens which is manual only.

On the Canon T3i, there is a very useful feature which allows magnifying part of the Liveview picture. Magnification can be set to x1, x5 or x10. This helps tremendously with focusing distant objects.
Is there a way to do this with the Pentax K-r ?

So far, the only magnification of focus point that I see with the K-r is in AF Liveview mode.

3) Remote AF with Live View .

When using Liveview, the camera does not honor custom setting 14, "Autofocus when using remote control".
That might seem silly, but I like to use Liveview to compose the shot with the camera on a tripod, and then use the remote to actually focus and take the shot. As it is, I have to remember to turn off Liveview first before I use the remote to take the shot.
I guess this is documented on p148 on the manual. But still a bit annoying.

06-02-2012, 06:53 AM   #2
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There are a number of posts discussing the AF differences between the OVF and Live View. Personally, unless I'm shooting video where I have no choice, I almost never use Live View. So I am a poor person to comment on your concerns with one exception, manual focus. How are you trying to manually focus in Live View? Are you using the lens' Quick Shift capabilities or are you using the K-r's switch next to the lens mount to specify manual focus?

I just tried to duplicate your issue with manual focus and could not. I was using my K-r with the kit 18-55 in low light and Live View; the body was in P (program) mode, no flash, and I had to boost ISO to 1600 to get a shutter speed under a second (and really should have gone to 6400). My subject was about 3 feet (1m) away. This is as close as I could get to your restaurant scenario. This lens does not support Quick Shift, so I flipped the body switch to the MF position. I had no problem with manually focusing or taking my properly focused test photo.
06-02-2012, 07:47 AM   #3
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I found the same thing on the Kx, so I simply either manual focus or use the OVF. That live view focusing will be pretty slow in bright light too compared to the OVF.

I would probably go through the manual with a fine tooth comb to seek the answers you are looking for though. I know the Kx and the Kr are similar, but there are differences, so I can't answer about any magnification settings, and I never use a remote.
06-02-2012, 03:45 PM   #4
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Jim,

QuoteOriginally posted by JimJohnson Quote
How are you trying to manually focus in Live View? Are you using the lens' Quick Shift capabilities or are you using the K-r's switch next to the lens mount to specify manual focus?
I'm specifically interested in doing this with a manual focus lens, my 800mm Rokinon T-mount mirror lens, which has no electronics and no AF. Thus, there is no quick shift involved.

QuoteQuote:
I just tried to duplicate your issue with manual focus and could not. I was using my K-r with the kit 18-55 in low light and Live View; the body was in P (program) mode, no flash, and I had to boost ISO to 1600 to get a shutter speed under a second (and really should have gone to 6400). My subject was about 3 feet (1m) away. This is as close as I could get to your restaurant scenario. This lens does not support Quick Shift, so I flipped the body switch to the MF position. I had no problem with manually focusing or taking my properly focused test photo.
What focal length were you at ? At 18mm with an 18-55 lens on my T3i, the Liveview AF works correctly, but at 55mm it fails.
On the K-r , at 50mm with the F 50mm f1.7 prime, the Liveview AF fails . I have not tried other lenses combination. But I do have a very reproducible test case, once night time comes.

06-02-2012, 03:47 PM   #5
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VoiceOfReason,

QuoteOriginally posted by VoiceOfReason Quote
I would probably go through the manual with a fine tooth comb to seek the answers you are looking for though. I know the Kx and the Kr are similar, but there are differences, so I can't answer about any magnification settings, and I never use a remote.
Yes, I have been through the manual already. This is why I'm posting here. I can't really find any info about manual focus with LiveView. Magnification in LiveView is an obvious benefit for manual focus.
Otherwise, I have to use a separate magnifying eyepiece with the OVF. But the eyepiece itself needs focusing too, so this is not as reliable.
06-02-2012, 05:42 PM   #6
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QuoteOriginally posted by madbrain Quote
What focal length were you at ? At 18mm with an 18-55 lens on my T3i, the Liveview AF works correctly, but at 55mm it fails.
On the K-r , at 50mm with the F 50mm f1.7 prime, the Liveview AF fails . I have not tried other lenses combination. But I do have a very reproducible test case, once night time comes.
Okay, it was dark enough in my office that at 128000 ISO, I was shooting at 1/15 @ f/4.0...Other than plugging in a mirror lens (I don't own one), I've tried to duplicate all aspects of your scenario.
I used both my DA L 18-55 kit lens and my Pentax A 28mm f/2.8. I was able to manually focus the 18-55 across the entire zoom range. Likewise, I manually focused my 28mm lens (it has no auto-focus). I used both the A setting and a manual aperture. I could also hit the info button and zoom in during Live View. I had no problem taking a picture.

Here is my question, where do you have your AF/MF switch on the side of the camera's lens mount? I have specifically told my camera that I am using manual focus (MF) position. Per the manual, none of the Live View AF options matter when you tell your camera you will be handling the focus yourself.

Also, from the manual: When the aperture ring is set to other than the A position or a lens without an A position....are used, the camera will not operate unless [22. Using Aperture Ring] is set to [Permitted] in the C/4 menu.
06-02-2012, 11:55 PM   #7
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Jim,

QuoteOriginally posted by JimJohnson Quote
I could also hit the info button and zoom in during Live View. I had no problem taking a picture.
Ah, that was the trick - the info button. Guess I missed that part of the manual. It works fine ! Thanks.

QuoteQuote:
Here is my question, where do you have your AF/MF switch on the side of the camera's lens mount? I have specifically told my camera that I am using manual focus (MF) position. Per the manual, none of the Live View AF options matter when you tell your camera you will be handling the focus yourself.
Typically I leave the camera setting on AF, as I normally only use AF with AF lenses. I only want to MF with MF lenses. And I don't need to set the camera to MF for that, it knows it cannot AF with the MF lens already.

QuoteQuote:
Also, from the manual: When the aperture ring is set to other than the A position or a lens without an A position....are used, the camera will not operate unless [22. Using Aperture Ring] is set to [Permitted] in the C/4 menu.
Yes, I have that set, otherwise could never shoot with the mirror lens.
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