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06-12-2022, 05:36 AM   #1
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Few Questions I cannot clarify from my Google Fu

Hi all

I'm just debating upgrading from a k3 mk1 to a mk3 as well as a new set of lenses.. not a cheap exercise!

I dont do much video but would like the ability to.. Am I to understand correctly that the mk3 only does autofocus with PLM lenses? So if I had the 70-200 F2.8 or the 24-70 F2.8 or the 18-135wr, it would be manual focus only?

Secondly - I've watched videos, read reviews etc.. but still cannot get a feel for how good the actual auto focus is in both OVF and liveview? So many varying opinions around.. and contrasting results. With both my current tamron lenses (28-75 and 70-200 F2.8) liveview on my MK1 is not useable - it always is out of focus by an absolute mile.. but fine on my crappy 16-45 pentax.. I have other issues with the tamrons but they really dont seem to be compatible. I'd love to know your thoughts on tracking etc with fast moving objects (like a 5 year old boy!)

My other post about being at a crossroads has been a really good balanced and sensible discussion!

Thanks

Steve

06-12-2022, 09:26 AM   #2
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Probably not a lot of help … I do very little video, but the K-3iii certainly does autofocus … what it may NOT do is continuous autofocus (tracking) in Movie mode with some lenses.
One would need to clarify exactly what the question is then research further.
Similarly, I use very little LiveView, especially with the K-3iii and it's fixed screen, nor do I have your mentioned Tamron lenses, though I do have an old Sigma 70-200mm f/2.8 which works seamlessly with the OVF and other Tamrons which I have no problems with.
Using the OVF, I track wild birds on a regular basis with little problem, PROVIDED I keep the subject reasonably centred. The K-3iii is better than the KP (and the K-70) in this respect, but how it compares to other manufacturers I don't know.
06-12-2022, 11:29 AM - 1 Like   #3
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Don't do video at all so cannot help there.


As for AF: OVF is a blast. I track incoming trains, airplanes, sometimes cars etc and when it get something in focus, it keeps it there. I once tracked bumblebee going crazy over flower. Cannot say about more advanced functions like eye tracking as I do not photograph people. But I would get 16-50 PLM together if you want to use all abilities of this camera. Slower AF engine may struggle with keeping up with camera.

Live view AF on the other hand sucks. Really, It often struggles to get building in focus hunting up and down like crazy. I do not know how it is possible as LV AF should be more accurate then OVF one even if slower, but it i what it is.
06-12-2022, 11:47 AM   #4
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QuoteOriginally posted by 5teve Quote
Hi all



I'm just debating upgrading from a k3 mk1 to a mk3 as well as a new set of lenses.. not a cheap exercise!



I dont do much video but would like the ability to.. Am I to understand correctly that the mk3 only does autofocus with PLM lenses? So if I had the 70-200 F2.8 or the 24-70 F2.8 or the 18-135wr, it would be manual focus only?



Secondly - I've watched videos, read reviews etc.. but still cannot get a feel for how good the actual auto focus is in both OVF and liveview? So many varying opinions around.. and contrasting results. With both my current tamron lenses (28-75 and 70-200 F2.8) liveview on my MK1 is not useable - it always is out of focus by an absolute mile.. but fine on my crappy 16-45 pentax.. I have other issues with the tamrons but they really dont seem to be compatible. I'd love to know your thoughts on tracking etc with fast moving objects (like a 5 year old boy!)



My other post about being at a crossroads has been a really good balanced and sensible discussion!



Thanks



Steve
Auto focus doesn't work in live view when the Tamron 70-200 is used on a K-50 either. I think it is a well known issue but takes you by surprise when you first experience it.



06-12-2022, 12:36 PM   #5
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QuoteOriginally posted by 5teve Quote
Am I to understand correctly that the mk3 only does autofocus with PLM lenses?
No that is not correct.

QuoteOriginally posted by 5teve Quote
Secondly - I've watched videos, read reviews etc.. but still cannot get a feel for how good the actual auto focus is in both OVF and liveview?
All the reviews I have read show a distinct improvement in AF in OVF.
06-12-2022, 01:04 PM   #6
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The K3mk3 is extremely fast focusing with both released Pentax lenses (16-50mmf/2.8 PLM & 55-300mm f/4.5-6.3 PLM). My screwdriven Tamron 17-50mm f/2.8 works fine with the OVF and slow with Live view, with hunting.
If you are investing into the new K3mk3 I would suggest purchasing one of those PLM speed deamons.

The K3mk3 is not only the improved AF system beneficial with most existing AF lenses, but the sensor is a vast improvement regarding the previous generation regarding low light performance, shadow recovery. The main reason why I purchased this camera.
The K3mk3 is a very nice camera but also a complex camera regarding AF modes. Time is needed to understand the various AF modes.
I am not into video so I am of no, little help.
06-12-2022, 04:58 PM   #7
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QuoteOriginally posted by 5teve Quote
Hi all

I'm just debating upgrading from a k3 mk1 to a mk3 as well as a new set of lenses.. not a cheap exercise!

I dont do much video but would like the ability to.. Am I to understand correctly that the mk3 only does autofocus with PLM lenses? So if I had the 70-200 F2.8 or the 24-70 F2.8 or the 18-135wr, it would be manual focus only?
The manual isn't a lot of help here, it just says AF in movie mode with compatible lenses, no definition of compatible. I fooled around with it for a bit with the DA 18-135. While recording video, I can use the touch screen to refocus on something else. So I think it'll work. But in movie mode, on the screen it tells me I'm in AF-S and I can't even find a menu item for that. I don't have a PLM lens to see how those work.

06-12-2022, 05:34 PM   #8
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QuoteOriginally posted by jersey Quote
Don't do video at all so cannot help there.


As for AF: OVF is a blast. I track incoming trains, airplanes, sometimes cars etc and when it get something in focus, it keeps it there. I once tracked bumblebee going crazy over flower. Cannot say about more advanced functions like eye tracking as I do not photograph people. But I would get 16-50 PLM together if you want to use all abilities of this camera. Slower AF engine may struggle with keeping up with camera.

Live view AF on the other hand sucks. Really, It often struggles to get building in focus hunting up and down like crazy. I do not know how it is possible as LV AF should be more accurate then OVF one even if slower, but it i what it is.
My old Tamron AF 70-200 f/2.8 IF Macro focuses just fine using live view and touch AF
06-12-2022, 06:11 PM   #9
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I think live view on the k3iii is CDAF only. The sensor lacks the embedded PDAF that newer mirrorless systems have. The embedding of PDAF can lead to banding and takes away a few pixels that otherwise add to the overall resolution. But I’m not certain the camera lacks PDAF embedded sensors. The k-70 has them, The KP does not. The k-70 only uses them in video mode if I recall correctly.
06-13-2022, 01:18 AM - 1 Like   #10
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From what I can see, AF-C in movie mode needs PLM. The K-3iii manual is useless at giving that information, but if you look at the specifications of the individual lenses only the PLM ones claim to be able to continuously focus in movie mode. I don’t have any PLM lenses, so can’t say how good the AF-C is.

If video is a major use-case for you, I would suggest other options would be better.

The AF-C for normal photography is light years ahead of previous Pentax DSLRs, but still takes some practice and experimentation. I have found even the older SDM of the DA*300 can produce good results with birds in flight with lots of Z axis motion (eg puffins flying towards you). For portraits I still rely on AF-S single and focus/recompose to nail the eye focus. I have tried using face/eye detection and it works quite well, but isn’t close to 100% perfect.

The high ISO performance is a bit better than the K-1, and the stabilisation is substantially better.

The LV focus seems quick and accurate with most lenses, but I still find the Sigma 18-35 F1.8 can be hit/miss in both LV and OVF modes. The touchscreen is very responsive and allows easy focus point selection in LV.

I’ve had the K-3iii for almost a year now and it is my choice for action/walk round. K-1 still has an edge for portrait and landscape, but that is probably partly down to the lenses: DFA 15-30, DFA* 50 and FA ltd 77 are better than the equivalent lenses I have for APSC.

Hope that helps
06-13-2022, 02:19 AM   #11
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QuoteOriginally posted by Larrymc Quote
My old Tamron AF 70-200 f/2.8 IF Macro focuses just fine using live view and touch AF
Good to know live view works for the Tamron 70-200, it didn't work on earlier cameras. I first realised when trying to shoot the moon in live view on a K-50, I had to revert to the viewfinder. Then I googled and found this.
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/323189-tamron-70-200-f-2-8-af-question-post3672521.html

Last edited by slartibartfast01; 06-13-2022 at 02:34 AM.
06-15-2022, 11:54 AM   #12
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The K-70 and KP are the only Pentax Cameras that allow full time AF.C while shooting video with both DC and PLM lenses. This leads me to believe that both the KP and K-70 have phase detect on sensor.
The K-3 III does not do full time AF.C in video without a PLM lens. However, the focus is still very quick with DC lenses attached when you refocus using the touchscreen.
06-15-2022, 12:18 PM   #13
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QuoteOriginally posted by Kobie Quote
The K-70 and KP are the only Pentax Cameras that allow full time AF.C while shooting video with both DC and PLM lenses. This leads me to believe that both the KP and K-70 have phase detect on sensor.
The K-3 III does not do full time AF.C in video without a PLM lens. However, the focus is still very quick with DC lenses attached when you refocus using the touchscreen.
Multiple sources have concluded the KP does not have onsensor PDAF - I think the K-70 and K-3iii are the only Pentax APSC bodies with it and I don't think the K-1 has it either.
06-15-2022, 01:45 PM   #14
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QuoteOriginally posted by UncleVanya Quote
Multiple sources have concluded the KP does not have onsensor PDAF - I think the K-70 and K-3iii are the only Pentax APSC bodies with it and I don't think the K-1 has it either.
I hear you but that doesn't make sense if the only cameras that can do AF.C full-time in video from Pentax with DC lenses are both the K-70 and KP. If the K-3 Mark III had on sensor phase detect, it would work in video as well for DC lenses. The only common denominator here would be the on sensor phase detect from the K-70 also being used in the KP to have both DC and PLM lenses do full-time AF.C in video. K-3, K-3 II, K-3 III, K-1 K-1 II don't have that ability.

Last edited by Kobie; 06-15-2022 at 02:24 PM.
06-15-2022, 02:52 PM   #15
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QuoteOriginally posted by Kobie Quote
I hear you but that doesn't make sense if the only cameras that can do AF.C full-time in video from Pentax with DC lenses are both the K-70 and KP. If the K-3 Mark III had on sensor phase detect, it would work in video as well for DC lenses. The only common denominator here would be the on sensor phase detect from the K-70 also being used in the KP to have both DC and PLM lenses do full-time AF.C in video. K-3, K-3 II, K-3 III, K-1 K-1 II don't have that ability.
The Pentax Forums review suggests that it DOES have PDAF pixels:
Pentax KP Review - Focusing | PentaxForums.com Reviews

I'm totally confused now.
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