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06-03-2018, 12:14 PM - 16 Likes   #1
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K-1 II AF-C Real World Report

For those not on both DPR and PentaxForums

On DPR when I mentioned I got my K-1 upgraded to a K-1 II I also said I had an airshow coming up and would report back on the new AF-C.

I went through all the photos, 1249 that were relevant to AF-C performance, I tried hard to identify the issues with those that weren't perfect, I split the bad ones into these categories. 1) Motion blur due to slow shutter speeds. 2) Out of focus (miss-focus by the camera, however some are as a result of atmospheric distortion, sun glare, heat haze, smoke haze, or the camera focusing on the smoke trail) so it may not be as bad as reported if you give a pass to the camera for some of those issues. 3) Heat ripples, not an AF-C problem unless they cause the AF to miss, these were just blurry due to heat ripples. 4) Clipping, well certainly not an AF issue but a user error issue.

Initially I felt there was little to no improvement while chimping during the airshow, however most of that turned out to be motion blur slow shutter speed panning issues. Its very hard to balance shutter speed and prop blur especially when the planes aren't flying in a straight line, banking, pitching, yawing, doing crazy aerobatics all ruin slow shutter speed photos. I wanted there to be a noticeable improvement not just for Pentax's benefit or good news to the forum but also for my benefit as the upgrade wasn't cheap. I set out to concentrate on getting the best results I could but I got easily caught up in the moment and made the usual lack of concentration mistakes and I doubt my intention resulted in any skewing of the results. I used shutter speeds from 1/200th to 1/8000th sec, AF-C, AF Hold off and low, Expanded area 9 and 25, focus priority (not that it works), A wide range of ISOs and Apertures, the Sigma 100-300mm F4.0 and Sigma 500mm F4.5 both with and without the Sigma 1.4x TC. I also hadn't been to an airshow in over a year, I missed last year as other things came up.

In the past I figured I'd average 40-60% keepers at an airshow, this didn't isolate just the miss-focus issues but all issues that related in a deletion.

410 of the 1249 photos were deemed delete worthy in the previously mentioned categories (32.8%) so already a bit better than previous years. 16.7% were a result of the camera missing focus, 10.8% were a result of motion blur, 3.4% a result of heat ripples and just 1.8% a result of user error frame clipping.

At just 16.7% miss-focus I have to say I'm pretty happy with the K-1 II, thats about 1 in 6 photos where the camera missed. assuming the ratios are similar for each show over a broad average one could suggest that the camera performed at least 12% better then the estimated best from the original K-1, and possibly 34% or more better.

Its no Canon or Nikon that might miss 1 in 10 or 1 in 20 but its good enough at 1 in 6 being a miss.

Here are a few points I figured I'd share from this exercise, some mentioned above

- Most OOF photos come at the beginning of a burst
- As always if focus isn't ideally acquired on the first shot of a burst it can ruin the rest of them
- Sometimes the camera figures it out and re-acquires lock
- Sometimes the camera looses focus despite having it in the first place
- Sometimes its hard to figure whether the item was out of focus or just had too much atmosphere in the way. The further the subject the greater its chance of appearing out of focus, that too could be as a result of too much atmosphere, It wouldn't be a worthy photo anyways
- The camera did well with an F18 jet coming in fast straight towards me with the sigma 500mm F4.5 until the last shot
- typical things like loss of contrast (shooting very close to the sun) would help the camera lose focus
- I did keep some slightly out of focus photos
- I did keep some slightly motion blurred photos
- Smoke haze contributed to some out of focus results
- On a few occasion the trailing smoke is what the camera preferred to lock onto
- Sometimes Out of focus shots were a result of heat haze or atmospheric distortion, even though listed as out of focus its hard to fault the camera on those
- Of course if the plane went outside the focus point area the camera would drop focus

The photos of this event will come in time, they've yet to be edited.

Final thoughts, airshows aren't the be-all and end-all of AF tracking, far from it. I did find out there was an improvement but to what degree will be user and subject dependent. I suppose YMMV. However my results seem to be in line in some degree with all the other reviews saying AF-C is mildly but noticeably improved. These AF improvements will not compensate for sloppy photography so don't think you won't have to keep working at it to get the best out of it. Its up to you to determine if this improvement is worth the money or not. I'm happy as I'll take any improvement I can get without having to switch systems or spend a fortune. I'm going to try to get out and shoot some terns in flight, some footie and there is another airshow coming up too, I doubt I'll give as detailed a report from them but I probably will comment on any noticeable difference over my experience with the K-1.

06-03-2018, 12:23 PM - 2 Likes   #2
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Really appreciate this. Knowing this isn't your first airshow and seeing how you systematically check your photos for cause and effect gives your report a lot of credibility and is truly useful information.
06-03-2018, 12:24 PM - 1 Like   #3
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QuoteOriginally posted by MightyMike Quote
These AF improvements will not compensate for sloppy photography
D*mn...
Thanks for the report, I hope you'll write more as you continue to use the camera.
06-03-2018, 12:29 PM   #4
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QuoteOriginally posted by RGlasel Quote
Really appreciate this. Knowing this isn't your first airshow and seeing how you systematically check your photos for cause and effect gives your report a lot of credibility and is truly useful information.
I appreciate that you appreciate the report, I hope it helps people.

---------- Post added 06-03-18 at 03:30 PM ----------

QuoteOriginally posted by Kunzite Quote
D*mn...
Thanks for the report, I hope you'll write more as you continue to use the camera.
Thanks Kunzite, Other than other AF-C targets which will likely yield similar results I'm not sure what else needs reporting on.

06-03-2018, 12:41 PM - 1 Like   #5
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Thanks for the report, an interesting read.
F-18 are slower than bicycles though, I reckon..?
06-03-2018, 12:46 PM   #6
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Thanks for this, Mike. Real, honest user reports - especially from someone with experience - are always of more interest to me than bench tests.

In time, when you've processed your photos, could I ask you to consider posting about the overall image quality? I'm sure I wouldn't be the only member here to value your findings...
06-03-2018, 12:52 PM   #7
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QuoteOriginally posted by MightyMike Quote
Thanks Kunzite, Other than other AF-C targets which will likely yield similar results I'm not sure what else needs reporting on.
Whatever you feel it's worth reporting; it will be appreciated.
Except for depressing stuff like "the camera can't replace photographer's skill"
06-03-2018, 01:09 PM   #8
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QuoteOriginally posted by Kunzite Quote
D*mn...
Thanks for the report, I hope you'll write more as you continue to use the camera.
I was hoping that acquiring a K-1II would solve my user's errors !!

06-03-2018, 01:14 PM - 3 Likes   #9
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QuoteOriginally posted by LensBeginner Quote
Thanks for the report, an interesting read.
F-18 are slower than bicycles though, I reckon..?
Well since its a Canadian Air Force F-18 it might be slower LOL
06-03-2018, 01:18 PM   #10
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Thanks MightyMike - facts and actual data is what we need in heated K-1 vs. K-1 II debate.
06-03-2018, 01:20 PM - 2 Likes   #11
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QuoteOriginally posted by BigMackCam Quote
Thanks for this, Mike. Real, honest user reports - especially from someone with experience - are always of more interest to me than bench tests.

In time, when you've processed your photos, could I ask you to consider posting about the overall image quality? I'm sure I wouldn't be the only member here to value your findings...
I agree bench tests can only tell you so much, however in the same way real world examples can't easily be scientific.

Image quality (pixel level) isn't an area where I will be too critical as in its more than good enough. Yes at first I was apprehensive about baked in NR but I've come to the realization that you need to pixel peep to see the difference and optyczne.pl reports just a 1.1lpmm difference which is usually within the margin of error in a lens test and certainly within the range of sample variation between lenses. Therefore I'm not worried about it. However if there is something to say I'll be sure to mention it.
06-03-2018, 04:13 PM   #12
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Handy field report.

Would be useful to know what your AF-C (and metering too) settings were, or at least the settings that produced the best results out of those 1249 AF-C shots.
06-03-2018, 04:43 PM   #13
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QuoteOriginally posted by rawr Quote
Handy field report.

Would be useful to know what your AF-C (and metering too) settings were, or at least the settings that produced the best results out of those 1249 AF-C shots.
I consistently use center weighted metering and EV adjustments on occasion.

AF-C settings were as stated, 9 and 25 point SEL, 1st frame and continuous set to focus priority even though it doesn't ever work as advertised, AF hold off or low and it appears I may have used medium toward the end. Its not like changing any of these settings up lead to better or worse results. You pick the settings appropriate for the subject matter. If the subject is moving around the frame a lot then activate more points, if you have obstructions then set a higher AF hold. DPR suggested release priority was best but I've never used that option ever since its availability in Pentax cameras.
06-03-2018, 06:29 PM - 1 Like   #14
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QuoteOriginally posted by MightyMike Quote
I consistently use center weighted metering and EV adjustments on occasion.
Interesting. I always ask about metering settings because in many camera brands it seems to have an influence on AF-C effectiveness. In Nikon, for example, AF-C '3-D tracking' relies on matrix metering to feed subject colour movement into the AF calculations, and centre-weighted and spot just can't support '3-D tracking' AF-C effectively. I believe it's the same with Pentax, particularly those bodies with access to the 86K metering sensor:



QuoteOriginally posted by MightyMike Quote
AF-C settings were as stated, 9 and 25 point SEL, 1st frame and continuous set to focus priority
Cool. I wish it was easier to move those SEL clusters around. The 4 way controller is a bit awkward for me.
06-03-2018, 06:36 PM   #15
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QuoteOriginally posted by LensBeginner Quote
Thanks for the report, an interesting read.
F-18 are slower than bicycles though, I reckon..?
I know you included a "smiley", but this actually isn't a straight forward question. A faster object can be less of a focus challenge than a slower one is if the faster one is farther away, because the real issue is how fast is the percentage distance changing.
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