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06-11-2011, 04:03 PM   #1
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SAFOX IX predictive AF tracking?

From what I have read, SAFOX VIII did not appear to have any predictive AF tracking capability. It seems this has changed with SAFOX IX. My experience with my K-r in action shooting shows that the AF system seems to continue to move the lens focus based on previous tracking even as the subject left the AF area. While I have never owned any previous PENTAX DSLR camera, does this mean that there is at least rudimentary predictive AF tracking in SAFOX IX? What is your experience with AF.C on the latest cameras?

--DragonLord

06-11-2011, 04:34 PM   #2
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Yes, the AF-C is quite usable now. It was not able to keep up with a vulture flying on me with K10D but with K-5 it is.
06-11-2011, 07:13 PM   #3
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Another reason to upgrade.......
06-11-2011, 07:37 PM   #4
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K5 + AF.C = much more "keepers" with moving subjects. (vs. K7 and K20D)

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06-12-2011, 03:32 AM   #5
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Only after I have upgraded to the K5 I have confidence in using AF-C. I tried AF-C on K10 and K7, but never used it in real shooting at sport events.
06-12-2011, 07:34 AM   #6
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Okay, I'm reading that there was predictive tracking in SAFOX VIII since the film *ist was introduced with this AF system (see Shutterbug article). However, people have reported that it performs very poorly and did not appear to be truly predictive. It appears that the algorithms involved have been improving over time and that SAFOX IX has significant improvements in both hardware and software that enable much better focus tracking. Am I right to say this?

--DragonLord

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06-12-2011, 07:53 PM   #7
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Hard to tell...

QuoteOriginally posted by DragonLord Quote
Okay, I'm reading that there was predictive tracking in SAFOX VIII since the film *ist was introduced with this AF system (see Shutterbug article). However, people have reported that it performs very poorly and did not appear to be truly predictive. It appears that the algorithms involved have been improving over time and that SAFOX IX has significant improvements in both hardware and software that enable much better focus tracking. Am I right to say this?

--DragonLord
Its hard to say. I believed my K20D could not track BIF. I believed it for a long time. One day looking for something to shoot I came across a bunch of gulls by the Detroit River. I decided to have some fun. I took about (going by memory) 200 pics. I used 11 point AF-C. I did not expect much. Looking at them with the K20D LCD it was hard to know what was in focus or was not in focus. When I got home I was shocked by the high hit rate. Moreover how the K20D and DA55-300mm nailed the AF and got tack sharp pics with fast moving birds. The hit rate was someplace between 40%-50%. Not too bad for what I was using.

The K20D does have some predictive AF. I read the link to the ShutterBug article And that's exactly what happened to me. The gulls would move outside of the 11 point AF sensor but I could still take pics. So yea its there.


The K-5 with its fast FPS and high ISO ability should make my keeper rate or number of keeps in a given time go up a lot. If AF-C is better on the K-5 then I will have a higher keeper rate. More folks should try BIF. Get the max out of the dSLR you have now. If you can't get BIF with a K20D then how will you get a good set of keepers with the K-5. Not to be taken personally just saying...

I have seen examples of BIF and tracking with most Pentax dSLRs.

OK some examples. This was tracking a fast gull. I tracked him even as it came down to the ground with a moving car behind it as it flew. This is phenomenal performance for the K20D and DA55-300mm.

A kid on a swing is not showing predictive AF only shutter speed, sorry. Although a very nice pic.

pic posted even if OOF its a series of photos that shows what you are looking for. Notice the K20D kept track even if the gull was out of one of the 11 AF points. No PP was done. So the last of the first series has some PP. The others are just some of the hundreds of sharp BIF pics I have. And I mean this guys turn and burn with afterburner on.








































Last edited by jamesm007; 06-13-2011 at 04:35 AM.
06-12-2011, 08:54 PM   #8
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The addition of new custom functions on the K-r and K-5 related to AF.S and AF.C priority seem to signal significant changes in AF algorithms. Are there any links to controlled tests of AF.C performance? I'd really like to see exactly how much things have improved...

I know AF performance is a much-discussed topic, but controlled tests are the only way to know for sure just how improvement has occurred.

--DragonLord

06-12-2011, 09:18 PM   #9
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Took this yesterday, K-5 AF.C had no problem locking focus on moving target even at f/1.9
06-13-2011, 03:45 AM   #10
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QuoteOriginally posted by TOUGEFC Quote
Took this yesterday, K-5 AF.C had no problem locking focus on moving target even at f/1.9
Not only it proves the point but it is a great photo as well. Congrats!
06-13-2011, 04:23 AM   #11
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QuoteOriginally posted by DragonLord Quote
From what I have read, SAFOX VIII did not appear to have any predictive AF tracking capability. It seems this has changed with SAFOX IX. My experience with my K-r in action shooting shows that the AF system seems to continue to move the lens focus based on previous tracking even as the subject left the AF area. While I have never owned any previous PENTAX DSLR camera, does this mean that there is at least rudimentary predictive AF tracking in SAFOX IX? What is your experience with AF.C on the latest cameras?

--DragonLord
All Pentax cameras with af-c have predictive tracking. In it's most simple way it is implemented as "keep running the focus motor with the same pace for a few milliseconds while the mirror is lifted". Hardly any rocket sience. I have had a lot of Pentax cameras and the first with AF was MZ-5. But the worst of them all was K10D. I don't know what Pentax did with that camera, but AF on my K10D was worser than on my old *istDS.
06-13-2011, 04:27 AM   #12
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QuoteOriginally posted by elho_cid Quote
Not only it proves the point but it is a great photo as well. Congrats!
Although a very nice pic... I have posted pics of what predictive AF is and how it works on Pentax systems. The pics above were all taken in AF-C mode 11 point AF, with the K20D and DA55-300mm. This exactly shows what shutter bug says. The K20D can track even if the subject moves out of one of the AF points for a few frames. It did move out then came back when in front of a moving car! Amazing!

Now the K-5 can do better (It should, but I don't own it) but not many try or perhaps understand what it can do.
06-13-2011, 05:21 AM   #13
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QuoteOriginally posted by DragonLord Quote
The addition of new custom functions on the K-r and K-5 related to AF.S and AF.C priority seem to signal significant changes in AF algorithms. Are there any links to controlled tests of AF.C performance? I'd really like to see exactly how much things have improved...

I know AF performance is a much-discussed topic, but controlled tests are the only way to know for sure just how improvement has occurred.

--DragonLord
I agree. Even my example proves nothing because maybe the D5100 tracks 10 times better. There are no controlled tests for this. It must be said however Canon and Nikon fought long and hard and improved AF systems to get the PROs photographer that needs it (sports...). So logical those two have the most advanced AF systems. But again who knows how much better?
06-13-2011, 06:55 AM   #14
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Few weeks ago I participated with my K-5 in a semi-controlled comparison of AF systems with BIF being the subject. Other cameras in the test were Nikon D300, Canon 7D and Sony A550. They all had 70-200/2.8 zooms, Canon and Nikon ultrasonic of course. I only had the Sigma 180 macro and FA*85 with me, both screw driven of course.
The K-5 did surprisingly well tracking the incoming birds. The success rate was slightly lower than D300 had but still much metter than the 7D. Perhaps it was the rookie photographer handling the 7D that caused the failure...
We should remember the man does the picture, camera is just a tool. K-5 is great tool.
06-14-2011, 01:02 AM   #15
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Links to some results of the great AF-C comparison can be found here on a (warning - in Czech) forum:
Test autofokus? - DIGIarena.cz
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