[starbase218]

Typical tricky photographic case is the one of slow walking person of a wedding in dim light in a church.
Regardless of the camera brand you use, Pentax, Nikon, Canon, if you use AFS, the subject inevitably has moved between the time of the AF lock ( t0 ) and the time of shutter open ( t1 ).
Now, if you use AFC (AI servo for Canon), you have the problem of tracking slow moving subject because prediction is not good.
I discussed this topic with Canon, and it's the same problem. Technically, there is always an error.

So, what's the solution?
Well, the solution is to use a fast lens and stop it down.

Why?
Because when the lens is wide open, the DoF is small and the camera focuses fairly accurately. And when the shot is taken, the lens diaphragm closes , that make a new DoF wider, so that the error due to the subject position having changed is still within a zone of acceptable sharpness. Faster lenses have two advantages even if not sharp wide open: 1) brighter viewfinder and 2) enhance AF accuracy

Moreover, if that technique is not sufficient for Pentax Canon Nikon because it is dark, you have two more options:
1) Set the camera AFS to FPS prio and shooting right after the first AF motion step.
2) Use the back button AF (what Canon and Nikon (AF ON) also added to their camera for a good reason)

Et voila.

You've been to laos... have you seen what's the standard of living over there compared to yours? And you complain about a camera AF that's a tiny bit slower in darkness. I mean, for some people, this is very very far from being a concern in life, as their main problem is to have food, electricity and water, and in-spite of their situation that is much worse than yours, they smile.

Best regard.

I've been smiling for a while now. I wasn't smiling when normhead and I were kind of negative towards each other, but that was ages ago. And I'm also smiling because of the way I handled that.

I'm not complaining, I'm just saying I have more confidence in Nikon's AF. Like I've said before, there's nothing wrong with that I think. I might be complaining if I hadn't bought the Nikon gear, because then I'd be frustrating myself. Also, if you have a DFA 28-105, you probably also have a K-1. So you've probably already spent way more money on your gear than I have. And you probably upgraded from an APS-C Pentax camera. I could therefore say the same to you: why upgrade to fullframe when you can be happy like the people in Laos?

By the way, Cambodia is in far worse shape than Laos. 1/4 of its population was murdered by Pol Pot in the 70s, and it was the intelligent 1/4. Teachers, thinkers, etc. They are still trying to recover from that. I've seen a man there, called Beat Richner, who has build children's hospitals. He could have probably chosen a career in the west and make a lot of money. But he choose that life. Makes you think (at least, it makes me think).

But you're right, our "problems" aren't really problems. We're just good at inventing problems because all our immediate needs are covered. Even Donald Trump, who has way more money than anyone of us, has "problems" (though maybe we shouldn't go there ). But then I have to ask: why was this topic even created?

The answer also is: whoever you are, whatever you do, however much money you have, try to be happy and at peace with yourself and those around you. If you can't change something, learn to see it in a positive way. If you can, you can change it. Laos is a Buddhist country as well.

I'm also not going to make a problem about what you wrote that there's always an error. That's evident. Still I have more confidence in Nikon's AF. I believe the error will be smaller. My initial testing seems to confirm that, though I haven't yet taken actual shallow DOF photos of moving subjects with it yet.

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Last edited by starbase218; 03-25-2017 at 12:40 PM.

[photoptimist]

Failing isn't the correct descriiption. Pentax won't be able to instantaneously upgrade every model and every lens to ultrasonic motors, and they won't magically be able to install a new AF sensor with 51 f/2.8 cross-type AF points in every camera body at whatever price, with predictive x, y and z axis Tracking AF algorithms that are idiot proof.

However, given a modicum of skill, technique and proper set-up, continuous AF functions are fine on Pentax cameras. Users whose immediate first priority is out-of-the-box Green Mode tracking and zippy AF for $600 should buy another brand.

Exactly!

Personally, I think Nikon and Canon are utterly failing on the image stabilization front (no stabilization for older lenses, limited selection of stabilized lenses, no stabilization of roll, no horizon leveling, etc.) yet plenty of people buy their equipment.

Could Pentax AF be better? Sure! But must it beat Nikon & Canon on AF to survive? No!

[jonlg]

Right - just arrived in New York at my Brother in law's house. Decided to have another play with the K1 and my Tamron 70-200mm f2.8 using our kids on a swing in his back garden. I've tried FPS priority, single center spot and 9 point autofocus and played around a bit with the focus hold settings from no focus hold to medium focus hold. Backdrop when shooting from in front of the kids on the swing is a wooden fence around 10 metres behind them. I'm getting a pretty low keeper rate - maybe 1 in 5 are acceptably in focus - much of the time the camera wouldn't fire at all because it couldn't lock focus at all for even 5 seconds or more - it just seemed to lock up and wouldn't shoot anything (despite setting release priority!) This is standing around 20 feet from the swing directly in front and aiming to fill the frame at around 70-100mm with a waist up portrait.

Best settings seemed to be AF-C, Burst rate high, single center point focus and no focus hold. I'm also wondering if there's any benefit to turning off image stabilisation?

I'm not an action shooter at all really but I don't think shooting a kid on a swing should be beyond the ability of an £1800 camera either. So if you were faced with shooting this scene how would you configure a Pentax K1 for best results?

The reason by the way I think a kid on a swing is a good test (as opposed to shooting a cyclist weaving down a street as DP review did is that it is more consistently repeatable in terms of motion for all of us because all swings move at a similar speed and in a similar axis of motion. Maybe we should all go out and shoot our kids on swings so we can compare settings and results?? If there are Nikon guys on here lets see too what the world's best autofocus maker can do...

That way we can determine the best settings for the K1/K3 etc.

Off to Manhattan today to visit Central Park amongst other things - at least Strawberry Field's won't be moving!! Really looking forward to shooting some top of the rock etc too this week. I'm very excited (as a Brit) to be here with the K1 - last time I was here in 2004 it was only for 1 night (on Concorde!) so no city photography, prior to that I was probably here with my MZ-5n around 18 years ago for my Brother's wedding. If any of my yankee friends on here have any 'must shoot' locations please do comment or send me a PM!!

Jonlg

[starbase218]

Concorde - so maybe you ARE just as rich as Trump?

Anyway, I was in a similar situation (not in terms of wealth, but photographically) when I tried shooting my little niece on a swing several years ago (actually right after that MotoGP race) using the K-3 and DA* 60-250. It also could not keep up at all. But to be honest, the images also didn't look that great. So I experimented, put the 16-50 on and prefocused at maybe 1 meter. Then I put the camera near the ground, pointing upwards, and shot her at 16mm. It turned out to be a great success. I got her, part of the swing, the surroundings and a nice sky behind her, with a lot of depth because of the wide angle. The only thing was that she was kind of dark, so I probably should have used a flash to brighten her up a bit. But other than that, it was great. Just looked up the image again, and she turns out not to be so dark - so actually, a pretty nice photo! So actually, in that case, the lack of focus speed wasn't so much of a problem.

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Last edited by starbase218; 03-27-2017 at 07:38 AM.

[jonlg]

No - not rich, just work for BA!

Mind you my Brother in law did have fun with his rather pompous New York neighbours who happened to drop by when they asked me how long we were staying and I casually remarked we'd only come in for one night on the Concorde to meet him for dinner and were going back the following day....

Their faces were a picture worth taking LOL!!

J

[starbase218]

No - not rich, just work for BA!

Mind you my Brother in law did have fun with his rather pompous New York neighbours who happened to drop by when they asked me how long we were staying and I casually remarked we'd only come in for one night on the Concorde to meet him for dinner and were going back the following day....

Their faces were a picture worth taking LOL!!

J

Thank you for making me smile once more.

[starbase218]

One last thing I want to say about my video: perhaps I did go a little overboard by implying the Nikon was in perfect focus. I mean, it wasn't bad (the metal ridge underneath the speaker is sharp) but maybe it wasn't perfect either. But I already explained that the lens isn't calibrated and that it did look much better on the screen than it does in the video. But yeah, maybe I shouldn't have said it that way in the video.

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Last edited by starbase218; 03-25-2017 at 03:01 PM.

[awscreo]

Interestingly, my AFC worked really well with panning/tracking of birds today. That's the first time I've tried it (not a wildlife shooter), and was surprised that I when I saw them took off I just pointed the camera, locked focus and tracked while shooting at Hfps. All shots in the sequence were in focus, but the birds were too far away from me, so I had to crop quite heavily to show it. Some sharpening applied to counteract cropping, but you can see that focus didn't hunt and didn't focus on the forest in the background for example.

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[Dan Rentea]

Interestingly, my AFC worked really well with panning/tracking of birds today. That's the first time I've tried it (not a wildlife shooter), and was surprised that I when I saw them took off I just pointed the camera, locked focus and tracked while shooting at Hfps. All shots in the sequence were in focus, but the birds were too far away from me, so I had to crop quite heavily to show it. Some sharpening applied to counteract cropping, but you can see that focus didn't hunt and didn't focus on the forest in the background for example.

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This is not a scenario in which you need a capable af-c because those birds fly perpendicular to the camera, are far away from you and because of that it's a lot easier to keep them in the frame. Also, due to the distance between you and the birds, you have enough DOF (even at f4) to keep them in focus.

[starbase218]

This is not a scenario in which you need a capable af-c because those birds fly perpendicular to the camera, are far away from you and because of that it's a lot easier to keep them in the frame. Also, due to the distance between you and the birds, you have enough DOF (even at f4) to keep them in focus.

True, this is already more challenging:



Still perpendicular to the camera, but closer up already (although this is a crop as well). I shot this with the K-7 (so no tracking at all) and the screw-driven 55-300.

I will say this though: there weren't many shots in proper focus like this one.

[awscreo]

This is not a scenario in which you need a capable af-c because those birds fly perpendicular to the camera, are far away from you and because of that it's a lot easier to keep them in the frame. Also, due to the distance between you and the birds, you have enough DOF (even at f4) to keep them in focus.

I have another sequence with the bald eagle flying away from me, shot through the branches. It was shorter (3-4 frames until I gave up), so I didn't post it. But every frame is in focus. The sequence I posted was shot at 2.8
Anyway, what I'm saying is that it works for me.

[The Squirrel Mafia]

Pentax KP Review: Digital Photography Review

^ Just came out. This link goes straight to the AF performance.

[Dan Rentea]

I have another sequence with the bald eagle flying away from me, shot through the branches. It was shorter (3-4 frames until I gave up), so I didn't post it. But every frame is in focus. The sequence I posted was shot at 2.8
Anyway, what I'm saying is that it works for me.

It wasn't a criticism. All I said is that your example is not concludent for someone interested in af-c. Your camera works for you, then you are a happy shooter and that's all that matters.

[monochrome]

Pentax KP Review: Digital Photography Review

^ Just came out. This link goes straight to the AF performance.

The review is fair and to the point. Some good points about KP. Some less so. AF is less so, even though they still insist on shooting a white shirt at f/2.8 using an RGB color tracking sensor. But whatever - Pentax AF can be made to work, but in general it is still behind.

[starbase218]

They say AF-S performance is quick and direct. So maybe there are substantial improvements relative to the K-3 after all.