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11-30-2013, 10:54 AM   #1
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Autofocus is difficult

Tried shooting a derby bout with my new K-3 on Sunday, the lighting wasn't great, and I was shooting at around ISO 6400/AV 2.8/TV 1/400 as a result. Perhaps it was the low light, but the autofocus wasn't really that much better, if at all, than the K-5. Or at least it felt that way. It'd frequently decide not to focus on the subject and rack in a bit to blur the whole thing out (this is all with the 50-135 and the 50/1.4), and even with the subject priority or whatever it's called set to high, it'd show a distinct fondness for the bright green walls rather than the purple and white skaters I'm trying to focus on. I tried a bunch of different focus modes, single point, expanded and all that.

Anyone else experienced similar difficulties with the AF? Or am I just expecting a bit much from a 1000 flagship camera? Any tips on working with it? It's possible there's just a learning curve.

Just to clear up as well, I'm not trying to troll or whatever, and the K-3 is a fantastic camera. It just seems the AF upgrade wasn't really all I thought it was cracked up to be.

11-30-2013, 11:29 AM   #2
Ole
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Speed-wise you should see a good improvement with the 50/1.4 screw-drive lens, whereas the autofocus speed with SDM lenses is about the same.

But I think you're more talking accuracy.

Moving subjects are quite difficult. The camera can't guess what you want to focus on, so for best results try centerpoint (spot) autofocus so as to avoid that the wall behind the subject gets in focus, or perhaps the "Select Small" setting, where the 9 centermost focus points are in play.

You'll have to experiment with what works best for you, AF.S or AF.C, and then also experiment with the related custom functions CF15 to CF18, where you can select between release priority or focus priority under various circumstances. There are almost too many combinations of settings that one can experiment with on the K-3. If you find a good, working combination please let us all know!

You could also consider the method of manually pre-focusing on the spot which the subject is moving into and then tripping the shutter at the right moment.

Without seeing some of your pictures it is hard to be more specific.
11-30-2013, 11:31 AM   #3
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QuoteOriginally posted by Mareket Quote
Anyone else experienced similar difficulties with the AF? Or am I just expecting a bit much from a 1000 flagship camera?
Without some more information, it's somewhat difficult to say.
Why don't you post a couple of typically lousy shots and a couple of good ones. I'd like to know more specifics about your AF mode and focal point settings.

Those are not-fast lenses in operation in good lighting, so under the seemingly tough lighting you were shooting under perhaps you reached the limits of their capabilities. Also 1/400 may not be enough to freeze action in roller skating. Did you try ISO 12,800? If the lighting was really poor, expectation for any camera may have to be limited.

M
11-30-2013, 12:35 PM   #4
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QuoteOriginally posted by Mareket Quote
Tried shooting a derby bout with my new K-3 on Sunday, the lighting wasn't great, and I was shooting at around ISO 6400/AV 2.8/TV 1/400 as a result. Perhaps it was the low light, but the autofocus wasn't really that much better, if at all, than the K-5. Or at least it felt that way. It'd frequently decide not to focus on the subject and rack in a bit to blur the whole thing out (this is all with the 50-135 and the 50/1.4), and even with the subject priority or whatever it's called set to high, it'd show a distinct fondness for the bright green walls rather than the purple and white skaters I'm trying to focus on. I tried a bunch of different focus modes, single point, expanded and all that.

Anyone else experienced similar difficulties with the AF? Or am I just expecting a bit much from a 1000 flagship camera? Any tips on working with it? It's possible there's just a learning curve.

Just to clear up as well, I'm not trying to troll or whatever, and the K-3 is a fantastic camera. It just seems the AF upgrade wasn't really all I thought it was cracked up to be.
Generally speaking, in low light the AF speed is a lot slower than in good light. This applies to just about about any camera and could definitely explain things, but as others have said it's hard to say without more specific info.


Adam
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11-30-2013, 02:11 PM   #5
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QuoteOriginally posted by Mareket Quote
a learning curve
The K-3 has more control options than a fighter jet.

So more practice with the camera is probably required to get the best out of it, especially for dynamic sporting scenes under low-light. Lots of experience with the way the game flows and the subject works, and the venue lighting, is also usually handy.

And the 50-135 or 50/1.4 wouldn't be my first choice of optics for shooting sports.
12-01-2013, 01:17 AM   #6
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QuoteOriginally posted by Ole Quote
Moving subjects are quite difficult. The camera can't guess what you want to focus on, so for best results try centerpoint (spot) autofocus so as to avoid that the wall behind the subject gets in focus, or perhaps the "Select Small" setting, where the 9 centermost focus points are in play.

You'll have to experiment with what works best for you, AF.S or AF.C, and then also experiment with the related custom functions CF15 to CF18, where you can select between release priority or focus priority under various circumstances. There are almost too many combinations of settings that one can experiment with on the K-3. If you find a good, working combination please let us all know!
Yeah I'll make a post if I find settings that seem to give good results, there's definitely a lot to learn with the new AF system. It is a little disappointing to just go back to using the centre point as well, especially when my subject is rarely in the centre, and frequently moves enough to warrant the expanded areas. I did get a lot of good shots this way though.

QuoteOriginally posted by Miguel Quote
Those are not-fast lenses in operation in good lighting, so under the seemingly tough lighting you were shooting under perhaps you reached the limits of their capabilities. Also 1/400 may not be enough to freeze action in roller skating. Did you try ISO 12,800? If the lighting was really poor, expectation for any camera may have to be limited.
QuoteOriginally posted by rawr Quote
So more practice with the camera is probably required to get the best out of it, especially for dynamic sporting scenes under low-light. Lots of experience with the way the game flows and the subject works, and the venue lighting, is also usually handy.

And the 50-135 or 50/1.4 wouldn't be my first choice of optics for shooting sports.
I know but they're the lenses I've got, and my K-5 is falling to bits, it wont turn off unless I take the battery out and it freezes up if you don't play nice with it. I was looking at the Sigma 85/1.4 but I'll have to start saving again for that. And in the mean time shoot more bouts. I've shot quite a few now so I know the game quite well. This was with two totally new teams though, so wasn't sure what they were planning. I'll just keep at it. And I daren't try 12,800, the shots are noisy enough at 6,400 as they generally need a push anyway. This is all in amateur little sports centres so the lighting is terrible.

QuoteOriginally posted by Adam Quote
Generally speaking, in low light the AF speed is a lot slower than in good light. This applies to just about about any camera and could definitely explain things, but as others have said it's hard to say without more specific info.
Yeah I figured as much, there was a guy there with a high end Canon and a 70-200/2.8 who was saying the lighting was shocking for autofocus so I was probably just pushing the system a bit far. AI was hoping some people might have tips on technique for it but I guess it's still early days. I'll keep at it and remark on anything useful I find.

In the mean time here are some of the lousy shots:











To be fair it's not even focusing on the wall in some so it's probably just having trouble keeping up, maybe a fault of the 50-135. Screw drive lenses are blazingly fast on the K-3, so I probably should have converted my SDM ones to screw drive before selling my K-x ah well.

And for good measure some of my favourite shots from the day:







12-01-2013, 01:52 AM   #7
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I'm not sure what you are complaining about You got some great shots.
A 100% keeper rate is just unrealistic sometimes, especially when you can't control all of the scene variables.

The other problem with low-light (and telephoto especially) is that it forces you to shoot wide open, which also means your DOF narrows down significantly. When subjects are in motion it means you have a very narrow plane of sharpness even if you get everything else right. You can see this in some of your shots. Just stopping down an extra notch from 2.8 to 3.2 can sometimes buy you an extra 10cm in-focus, for example.
12-01-2013, 02:40 AM   #8
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Thanks, the AF problems were more in use than in the shots I took. And I'd love to stop down a tad, but that means even higher ISO, and the shots are noisy enough as it is. Might be worth a try in the future though. I took about 500 shots on the day, of which I have 60 that I'm happy with, the split with the rest is about half bad composition, half out of focus (with a few out because of a zebra blocking the view :P).

Indoor sports sure are a pain...

12-01-2013, 04:42 AM   #9
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Are you waiting for the focus confirmtion beep? I think part of the problem might be simply not allowing enough time for it to lock focus. You might want to look at the C15, 16 & 17 settings if you haven't already.

I like to set these to C15=2, C16=1, C17=1. That way I take care to not release the shutter before I get a focus lock but then I leave it up to the camera for the remaining continuous shots to make sure the shutter doesn't release before focus is reacquired.

You might want to set C16 to 3 as well (focus priority) if you want the shot to be fired automatically as soon as focus is acquired.

Note however that the focus priority only waits a relatively short time for focus to be acquired and after that short time expires it will fire whether the image is in focus or not.

Forgive me if I'm explaining something you already know - I'm not familiar with the K-5 so I don;t know if these settings are new to you..
12-01-2013, 01:35 PM   #10
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No comment about the autofocus. But as a derby ref from Sweden I would say that you should get some shot of them too.


a zebra cant block the view, only improve it.
The zebras stripes are perfect for the crosstype AF of the k3
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