[kkoether]

Works pretty well for me!

[clackers]

Works pretty well for me!

Great shot, Keith!

[kkoether]

Great shot, Keith!

Thank you!

[crossed-up]

This thread had me thinking about some real world shooting situations that would show up an significant deficiencies in an AF system. So I looked through my galleries to find some examples. I haven’t got access to the originals just now so these are all processed and cropped images from my online galley, but I think they are valid in the context of the desire to capture useable images of a moving subject.

This was one such challenging (in my view) situation where the cars were coming into view at rally speed between a stack of tyres and a fence in failing light, so it wasn’t possible to track the car as it comes into view, only anticipate the moment the front of the car would come into view, at which point the AF would need to acquire/lock and then track as the far came towards me. There was then a brief opportunity to grab a panning shot as the car passed before it would disappear out of view again. All from very close range. Yes, I could prefocus on the tyre stack but the camera still had to work to lock and track for the head on shot, then relock (it it had lost focus) and track for the panning phase after I’d stood up and spun round, and zoomed for the pan.

I had the K3 and DA*50-135 (that renowned lighting fast focuser ) shooting AF-C centre point, Tv , burst and RAW. I got plenty of keepers and really only felt limited by my ability to keep the cars in frame and desire to remain out kneeling in the cold and damp.

Two consecutive frames in under 1 sec.
55mm 1/80 f4.5 ISO 200
Time 16:29:02


Time 16:29:02


Followed by 3 unusable frames due to speed and accuracy of framing whilst transitioning from crouching to panning position

Final panning shot before car disappears.

Time 16:29:03


The other shots from this session are here Snetterton Rally 2017 - Images | Simon Wood

This was another very similar situation but much less callenging due too the much better light and complete 180 degree view of the cars entering the stage, passing and leaving the stage, and I had a nice range of snacks and drinks with me to keep me going all day!

Same camera and lens combo shooting RAW again, but single shot mode. Whilst less challenging than the last situation, the brighter conditions did allow me to introduce the added complication of shooting at high shutter speed for the oncoming shot for a crisp image with the flying stones, before scrolling down the shutter speed for motion blur on the panning shot phase as the car passed. This is where the ergonomics of a camera probably become more important than the AF.

2 consecutive frames over 4 sec. period.

Time14:27:20
75mm 1/80 f11


Time 14:27:24
123mm 1/80 f11


Consecutive frames over 7 sec. period
Time 14:32:22
123mm 1/1000 f3.2


Time 14:32:23
123mm 1/1000 f3.2


Time 14:23:29
90mm 1/50 f14


Other images from this session are here Classic 30 Rally September 2014 - Images | Simon Wood

In both situations I missed shots but was more than happy with the keeper rate given the conditions and I’m really not sure I would have been better off with any other system - maybe, maybe not.

[normhead]

I've only used tracking on my K-3 a few times. But it's worked for what I used it for.

Terns over a school of minnows.

Dancers In Flight. From last week. K3II with DA 17-70, DA 50 -135 and Sigma 100-300/4 respectively

[clackers]

Fine examples, Crossed-up, Norm and Brooke!

Here's a Wedgetailed Eagle flying to the food behind and to the right of me:

---

Last edited by clackers; 03-22-2019 at 10:20 AM.

[sutherland]

Fine examples, Crossed-up, Norm and Brooke!

Here's a Wedgetailed Eagle flying to the food behind and to the right of me:

This photo really highlights Pentax's AF with some challenging variables:
- subject flying towards the camera
- higher contrast background
- a MOVING background that is of higher contrast

Any AF system can struggle with this scenario, but technique and a good understanding of the camera's settings always takes precedent over any 'heralded' AF tracking system (regardless of brand).

On my Nikon, I have yet to use the Auto, Dynamic (25, 72, 153), or 3D modes. It is Single Point or Group (a larger cluster of points), Back Button Focus, and the situational use of Focus Limiting/Focus Recall on the lens itself (features that are available on literally every DSLR on the market today).

[cmohr]

This has been my experience .


I've been playing with different setting for the AF-C on both my K-1 and K-3ii, What I have found to work the best is using AF-C in Select mode and choosing the most points available. With my selected point being the very centre point. I use the back button to grab focus on a bird, so as I am targeting the bird of my choice, (not letting the camera decide what it will lock focus on) once the AF locks onto the bird, the tracking follows the bird in the frame as it moves around, selecting the largest array of focus points, means that the tracking has a wide range of points to track with. If you only use centre or even 9 points in the middle, the tracking can only follow focus in that limited area of the frame, so very easy to loose tracking on a BIF. The accuracy of the focus in terms of sharpness, I find comes from how well the initial focus lock is. I used to shoot with frame rate over focus lock , but now prefer focus accuracy over frame rate, as once the focus is locked, the camera seems to be able to track the bird reasonable well across many panning situations, only times I do get a jump in focus is if say, another bird or object of high contrast gets close to the bird I'm tracking, then, it's generally only for 1 or 2 frame, then the tracking reacquires the target. As for the initial focus lock, I really find no real problem getting it, It's more up to making sure you are targeting well, and tracking is about, me being able to follow/pan the bird, keeping it in the AF area. That being said, IF the initial focus lock is slightly off (as tended to be the case with Frame rate over accuracy mode) the tracking followed the bird, but remained slightly off focus the entire time. So getting that initial focus lock seems to be the key in getting consistent tracking, thus my preference for accuracy over frame rate mode, and keeping the tracking going, relies on having the most amount of available points available to track across the frame.

I do have some tracking samples, I'll see if I can find them, and post them up later in the week.

[kevinWE]

@kevinWE, I would tend to agree with the first point -- there are plenty of user comments and images that attest to the AF capability of Pentax cameras, at least the more recent systems. Effective technique also plays into achieving well-focused images.

On the second point, would you happen to have more details on how Pentax AF lags other systems? Is your impression that Pentax AF is inferior to all systems, or only to specific brands/systems under certain conditions? Could you relate any relatively recent experience that you've had in this regard?

I think it would be useful to get your insight.

Sorry about the delay in a response, but I pop in and out of this forum. I'm sure I do not have to go into detail on how the Pentax AF lags behind other brands. It is well documented on this forum and elsewhere and Pentax itself knows of their short comings. You may find the AF of Pentax to meet your needs but many pros who shoot wildlife and sports seem to disagree with your opinion. As I said, it's a decent system, but not up to the standards that it could and should be.

[MarkJerling]

Sorry about the delay in a response, but I pop in and out of this forum. I'm sure I do not have to go into detail on how the Pentax AF lags behind other brands. It is well documented on this forum and elsewhere and Pentax itself knows of their short comings. You may find the AF of Pentax to meet your needs but many pros who shoot wildlife and sports seem to disagree with your opinion. As I said, it's a decent system, but not up to the standards that it could and should be.

I've just shot a wedding where almost every shot was perfectly focussed. I have posted may examples of perfectly focussed cyclists at speed, soccer players and other sport related fast moving subjects.

A lot of people want to believe, seemingly, that Pentax AF is useless, when it's not. If you're not going to provide detail of "how pentax lags behind other brands", then why bother to post?

[cmohr]

From a few years ago, and only a K-5, which so many seem to say is behind the K-3 and K-1.

Final day at the Quicksilver Roxy Surfing Pro 2012 (50 pics) - PentaxForums.com

also follow the links there to two more threads of photos. all sports, all fast action . all with the K-5 and a screwdrive 300mm +1.4xTC .

[clackers]

Sorry about the delay in a response, but I pop in and out of this forum. I'm sure I do not have to go into detail on how the Pentax AF lags behind other brands.

Hi Kevin, you will have to go into detail. We need facts, not anecdotes, and they're here:

See a German lab's testing of tracking in the difficult Z direction scientifically compared to other brands here: How does Pentax AF-C compare to other brands? - PentaxForums.com

[kkoether]

The boat is probably doing around 170 mph so with the angle of the shot maybe 150 to 160 mph closure rate. I'm happy. K-3 with a DA* 60-250mm.

[clackers]

The boat is probably doing around 170 mph so with the angle of the shot maybe 150 to 160 mph closure rate. I'm happy. K-3 with a DA* 60-250mm.

Beautifully done with what is said to be one of the slowest focusing lenses in K-mount!