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02-14-2014, 10:38 PM   #1
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K3 AF-C problems

Just tried out the k3 with a Sigma 70-200mm HSM lens in continuous shooting with AF.C mode.

There was noticeable camera shake blur in about 40% of the shots probably due to the SR system not stabilizing fast enough between frames (despite the the shutter speed being 1/400s at about 150mm and sloe panning which should not produce such blur).

Also, the "1ST frame Action in Af.C mode" setting does nothing as, regardless of what you set it to, if the lens is out of focus on the first shot the camera will start shooting and not attempt to focus. I think there must be a flaw in the firmware associated with this setting as it genuinely seems non-functional.

It seems these issues need to be addressed by Pentax engineers. Any similar experiences?

02-14-2014, 10:58 PM   #2
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I read ( can't remember where) that the 1st frame Action setting was meant for shutterpriority mode and to allow you to take a picture even if the subject wasn't fully in focus yet. Typically if you're at a fast moving sports event, then maybe a blurry image is better than no image.
About the af-c, I haven't tried it much on my k-3, but just shooting at seagulls flying low against an overcast and windy sky told me that I needed to actively follow a bird around in order to lock the autofocus - and once it was locked it would keep the seagulls in focus even if they flew in and out between the masts of sailboats and the like. - And as a note - it felt easier with light prime lens than a bulky zoom.
02-14-2014, 11:21 PM   #3
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What were you shooting? For sports, the general rule is to shoot at least at 1/1000s.
02-14-2014, 11:27 PM   #4
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QuoteOriginally posted by bgdisc Quote
What were you shooting? For sports, the general rule is to shoot at least at 1/1000s.
Things that are not moving; building, trees, etc. The blur is due to SR not engaging when the camera is being moved slowly. I guess if you are moving/panning the camera SR does not work and actually makes things worse.

02-14-2014, 11:45 PM   #5
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SR is meant to reduce motion blur due to slight shaking of the camera by your hands. It's doesn't work on motion of the subject. Furthermore, if you're panning the camera on still object (I have no idea what you're trying to achieve by doing this) then SR will not work as the movement is too large.
02-14-2014, 11:48 PM   #6
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On K5 I always get more keeper with SR off during panning. There's no separate SR setting like there is for long Cannikon lens so I just figure the SR algorithm on Pentax camera is just not specifically tuned for panning, more for general shooting.
02-15-2014, 12:52 AM   #7
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QuoteOriginally posted by Ayoh Quote
There was noticeable camera shake blur in about 40% of the shots probably due to the SR system not stabilizing fast enough between frames (despite the the shutter speed being 1/400s at about 150mm and sloe panning which should not produce such blur).
Turn the SR off? If you're shooting at 1/400 then you aren't going to benefit much from SR, especially if it's causing you problems like this. And I was told that using back button AF can help, as myself and others have noticed the K-3 has a tendency to be very particular about getting perfect AF before letting you fire off a shot if you set it to focus priority.

The K-3's AF for sports isn't great, but it's certainly not the SR that should be causing you problems.
02-15-2014, 01:08 AM   #8
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QuoteOriginally posted by Mareket Quote
The K-3's AF for sports isn't great,
This is interesting, I've been thinking of getting one as it's supposed to be far better than my K-30 regarding AF...

02-15-2014, 01:21 AM   #9
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QuoteOriginally posted by altopiet Quote
This is interesting, I've been thinking of getting one as it's supposed to be far better than my K-30 regarding AF...
Just look at some of the many shots in this thread. The K-3 seems to do OK for sport and birding.

What is apparent, however, is that due to the rich set of new AF options in the camera (there are about 10 different AF setting options just for AF.C), there is a learning curve involved in properly taking advantage of the K-3's AF. Just as there is for sports cameras like the 1Dx.
02-15-2014, 01:45 AM   #10
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QuoteOriginally posted by tom1803 Quote
SR is meant to reduce motion blur due to slight shaking of the camera by your hands. It's doesn't work on motion of the subject. Furthermore, if you're panning the camera on still object (I have no idea what you're trying to achieve by doing this) then SR will not work as the movement is too large.
Typical first response on this forum; whenever there is a problem with a camera it is by default the user's fault or a "design feature".

It is simple - when you pan the camera to focus on a different object (does tend to happen in practice) SR should not make your shot worse (by introducing camera shake) than it would be without SR enabled. That is a design shortcoming. In Canon and Nikon lenses there is mode to specify panning on IS lenses so stabilization is effectively maintained. On Pentax there is no such mode and apparently no effective detection of panning, which seems to introduce extra blur. The solution seems to be to turn of SR, but that is a pretty poor solution.

---------- Post added 02-15-2014 at 07:47 PM ----------

QuoteOriginally posted by Mareket Quote
Turn the SR off? If you're shooting at 1/400 then you aren't going to benefit much from SR, especially if it's causing you problems like this. And I was told that using back button AF can help, as myself and others have noticed the K-3 has a tendency to be very particular about getting perfect AF before letting you fire off a shot if you set it to focus priority.

The K-3's AF for sports isn't great, but it's certainly not the SR that should be causing you problems.
Turning off is crude solution - what if lightning conditions of the target change and now I'm shooting at 1/150s where SR may be useful? There should be a panning mode or SR should turn itself off if it cannot keep up.
02-15-2014, 02:13 AM   #11
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QuoteOriginally posted by Ayoh Quote
That is a design shortcoming
QuoteOriginally posted by Ayoh Quote
The solution seems to be to turn of SR, but that is a pretty poor solution.
QuoteOriginally posted by Ayoh Quote
Turning off is crude solution - what if lightning conditions of the target change and now I'm shooting at 1/150s where SR may be useful? There should be a panning mode or SR should turn itself off if it cannot keep up.
So what are you actually trying to say?
02-15-2014, 02:53 AM   #12
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QuoteOriginally posted by Ayoh Quote
In Canon and Nikon lenses there is mode to specify panning on IS lenses so stabilization is effectively maintained.
Hmmmmmm...........

From Nikon's own write up of VR:

QuoteQuote:
The system can also detect the use of a tripod, recognize panning―an instance in which you wouldn't want the lens to compensate for movement―and address the specific shake caused by the ongoing vibration patterns produced when shooting from a moving vehicle.
Vibration Reduction from Nikon

Basically in lens VR turns off stabilization in panning mode, or at best may stabilise the lens on one axis to compensate for vertical movement, but would not be able to do anything about horizontal movement (if that is the direction you are panning on)... .
02-15-2014, 03:32 AM   #13
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QuoteOriginally posted by Ayoh Quote
Turning off is crude solution - what if lightning conditions of the target change and now I'm shooting at 1/150s where SR may be useful? There should be a panning mode or SR should turn itself off if it cannot keep up.
Set SR to the RAW/Fx button and if you start creeping into slower shutter speeds you can toggle it with a simple button press. I shoot a fair bit of roller derby with the 50-135 on a K-3, that's low light, up close and personal action, and if I was to drop below 1/200 of a second I'd be much more worried about motion blur than camera shake, so I'd up the ISO.

QuoteOriginally posted by altopiet Quote
This is interesting, I've been thinking of getting one as it's supposed to be far better than my K-30 regarding AF...
Oh, make no mistake the AF on the K-3 is mind blowing compared to the K-5. It's just that I've had particular trouble in low light sports shooting that I'm currently trying to educate myself out of. The upgrades are welcome and very good, they're just still obviously lacking in certain (rare) ways. AF-S is amazing on the K-3, particularly with screw drive lenses.
02-15-2014, 03:50 AM   #14
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QuoteOriginally posted by Ayoh Quote
Typical first response on this forum; whenever there is a problem with a camera it is by default the user's fault or a "design feature".
My apologies if you were annoyed by my comments.

It was certainly not my intention to do so.
02-15-2014, 06:36 AM - 1 Like   #15
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I think the "panning"you are taking about is not the "panning" nikon is taking about. Panning generally means you keeping the shutter open while following a moving object and keeping them in the same place in your frame. What you are talking about is moving the camera around focusing on different objects and firing shots off at 1/400s. I wouldnt quote nikon or canon on having a special mode for this. Also it's hardly likely that at such shutter speeds SR is the problem (assuming you are not using 300+mm lens). I'm not saying that there isn't something wrong with your k-3, or its a design flaw, or you simply are using the wrong settings. I'm just saying at such shutter speeds sr shouldn't matter all that much so it's likely a focus issue
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