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12-03-2022, 03:54 AM - 1 Like   #61
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QuoteOriginally posted by UncleVanya Quote
I didn’t use back button af on my k-3 so I didn’t know it worked that way. It seems so simple to implement a model where if af is used it records into a register the af point then writes that to the file later.
I think the assumption is that if you let up on the AF button prior to hitting the shutter button that you are reframing at which point the stored auto focus information wouldn't make a difference. If you focus via a half press of the shutter button, I'm pretty sure the information is stored.

12-03-2022, 07:28 AM   #62
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QuoteOriginally posted by Rondec Quote
I think the assumption is that if you let up on the AF button prior to hitting the shutter button that you are reframing at which point the stored auto focus information wouldn't make a difference. If you focus via a half press of the shutter button, I'm pretty sure the information is stored.
I suspect you’re correct. In retrospectI guess I’d like it to record the focus point and indicate it wasn’t live at the time of the exposure but was at some point. However that’s of questionable value I guess.
12-03-2022, 04:04 PM   #63
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I tested with af.s XS and af.s auto area. I was floored the af.s auto area selected like 5 or 6 red focal points. On every shot. af.s XS red focal points every shot. Switched back to af.c pointed the camera at the dog half press. Full press. 2 shots. No red focus point selected. 3rd shot finally a red focal point was selected. I'll look at the images later on a monitor to see if they really have a focal point.


I don't back button focus.


If af.s works I can just not use the af.c ever.


My warranty is long expired.
12-03-2022, 08:06 PM - 1 Like   #64
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QuoteOriginally posted by idontstairs Quote
I tested with af.s XS and af.s auto area. I was floored the af.s auto area selected like 5 or 6 red focal points. On every shot. af.s XS red focal points every shot. Switched back to af.c pointed the camera at the dog half press. Full press. 2 shots. No red focus point selected. 3rd shot finally a red focal point was selected. I'll look at the images later on a monitor to see if they really have a focal point.


I don't back button focus.


If af.s works I can just not use the af.c ever.


My warranty is long expired.
For the life of me, I can't really understand what you are trying to do here? AF.c works like it it supposed to in Auto you are letting the camera select what should be in focus and it is probably not going to show anything in focus most of the time.

How do you have 1st Frame Action in AF.C set up? Auto, Focus Priority or Release Priority?


Last edited by Larrymc; 12-03-2022 at 08:12 PM.
12-04-2022, 06:16 PM   #65
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QuoteOriginally posted by Larrymc Quote
For the life of me, I can't really understand what you are trying to do here? AF.c works like it it supposed to in Auto you are letting the camera select what should be in focus and it is probably not going to show anything in focus most of the time.

How do you have 1st Frame Action in AF.C set up? Auto, Focus Priority or Release Priority?
I'm trying to get af.c to auto focus on the subject of a photograph. I had it set to focus priority for a long time and someone said to use auto instead. I didn't notice any improvement in auto so I set it back to focus priority.
12-04-2022, 11:16 PM - 2 Likes   #66
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QuoteOriginally posted by idontstairs Quote
I'm trying to get af.c to auto focus on the subject of a photograph. I had it set to focus priority for a long time and someone said to use auto instead. I didn't notice any improvement in auto so I set it back to focus priority.
I would re-iterate my questioning the use of AF C (and auto-area) on non-moving subjects, and have you tried using AF S spot instead of multi-focal points (and still check that the focal point is in the centre of the frame, and has not been inadvertently moved.
12-05-2022, 04:17 AM - 1 Like   #67
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QuoteOriginally posted by K2 to K50 Quote
I would re-iterate my questioning the use of AF C (and auto-area) on non-moving subjects, and have you tried using AF S spot instead of multi-focal points (and still check that the focal point is in the centre of the frame, and has not been inadvertently moved.
I've had several instances of soft focus when out hiking and going from birding to landscape/foliage and failing to switch over to AF.S. Shooting relatively static subjects using continuous focus is not nearly as successful. If that's what the OP is doing it would explain a lot.

12-05-2022, 06:10 AM   #68
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QuoteOriginally posted by gatorguy Quote
I've had several instances of soft focus when out hiking and going from birding to landscape/foliage and failing to switch over to AF.S. Shooting relatively static subjects using continuous focus is not nearly as successful. If that's what the OP is doing it would explain a lot.
That has been my experience also. In addition one can't expect absolutely everything to be in focus when using AF.Auto especially when shooting lower f/stop numbers with AF.Auto and continuous AF. One has to limit the size of the AF area to be even remotely successful.
12-05-2022, 06:44 AM - 1 Like   #69
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QuoteOriginally posted by gatorguy Quote
I've had several instances of soft focus when out hiking and going from birding to landscape/foliage and failing to switch over to AF.S. Shooting relatively static subjects using continuous focus is not nearly as successful. If that's what the OP is doing it would explain a lot.
I hope that isn't what we are talking about. AF-C is constantly adjusting focus based on perceived subject movement and if the subject isn't moving, it can move out of focus pretty easily or shift focus from one area to another.

It's a little bit like using shake reduction on a tripod -- the camera is looking for something that isn't there and it actually makes the end result worse. If you have a static subject, you are better off using AF-S.

Last edited by Rondec; 12-05-2022 at 01:20 PM.
01-02-2023, 02:07 PM - 1 Like   #70
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OK, update here..... I bought the FA*50mm F1.4. Pricey lens! Still much less expensive than switching systems. Very quiet focusing. Not used to that with Pentax lenses, as all my other lenses are screw drive. For full body portraits I tried using the top single selection AF point for the face. I was not expecting it to work well because it was not cross type. To my surprise, It focused well (event at f/1.4) after doing a lens AF fine-tune adjustment. If I select full or small zone, it focuses horribly for full body portraits. Head shots work well with a small or full zone and eyes are recognized.

Next I tried the same with my other 50mm and 70mm lens. Full body portrait, using zone AF results in terrible focus. Only either a single or three AF points selected at the top of the focus area works. Thinking that using spot focus at the belly (about midpoint of a subject) would result in best results is apparently not true. Even using 5 AF points in the center will not work work full body portraits, especially if the person is wearing red. With professional cameras many people say to always put the AF point on the face, and with a professional camera that has cross AF points all over the frame that makes sense. I just wasn't sure if that method would be adequate on the K3III. Seems the standard technique does work with the K3III. Optionally I could use the focus and recompose technique, but that led to focus errors that were noticeable.

At some point I plan to do a side by side comparison between the two 50mm Pentax lenses that are currently available and show the results.
01-02-2023, 07:43 PM - 1 Like   #71
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QuoteOriginally posted by Eric Seavey Quote
OK, update here..... I bought the FA*50mm F1.4. Pricey lens! Still much less expensive than switching systems. Very quiet focusing. Not used to that with Pentax lenses, as all my other lenses are screw drive. For full body portraits I tried using the top single selection AF point for the face. I was not expecting it to work well because it was not cross type. To my surprise, It focused well (event at f/1.4) after doing a lens AF fine-tune adjustment. If I select full or small zone, it focuses horribly for full body portraits. Head shots work well with a small or full zone and eyes are recognized.

Next I tried the same with my other 50mm and 70mm lens. Full body portrait, using zone AF results in terrible focus. Only either a single or three AF points selected at the top of the focus area works. Thinking that using spot focus at the belly (about midpoint of a subject) would result in best results is apparently not true. Even using 5 AF points in the center will not work work full body portraits, especially if the person is wearing red. With professional cameras many people say to always put the AF point on the face, and with a professional camera that has cross AF points all over the frame that makes sense. I just wasn't sure if that method would be adequate on the K3III. Seems the standard technique does work with the K3III. Optionally I could use the focus and recompose technique, but that led to focus errors that were noticeable.

At some point I plan to do a side by side comparison between the two 50mm Pentax lenses that are currently available and show the results.
Not clear here whether you used AF.S or AF.c here. I would re-iterate what I said in my first post in this thread (and what many others in this thread have said). If the subject is not moving, using AF.C is pointless, and asking for trouble.
01-03-2023, 12:26 AM - 1 Like   #72
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QuoteOriginally posted by pschlute Quote
That has been sorted with the introduction of the KP; the K1 II; and the K3 III


If memory serves me right

KP, K-3II and K-3 are actually the same AF system, just K-3II and KP got better algorithm (i.e. software).

K-1 uses a slightly improved system from K-3/K-3II/KP, the main difference is K-1 got more AF points on the sides. K-1II is same as K-1 but better algorithm (again).

K-3III of course is another story.

So basically I'd say there is 4 generation of AF system improvement in Pentax last 10 years

1. K-5IIS / K-5II

2. K-3/K-3II/KP/645Z
(Yes, 645Z using the same AF system)

3. K-1/K-1II

4. K-3III
01-03-2023, 03:05 AM   #73
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Ok, you are using AF-C for portraits right? It is possible, but set focus hold on high and try then. It will prevent refocusing when you or your subject move slightly after focus is established. For example when you press shutter. With in-lens motor that is not big issue but screwdrive lacks precision and speed for such minute and fast adjustements.


On the other hand why using AF mode designed for moving subject on static one?
01-03-2023, 03:44 AM - 1 Like   #74
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Why not just use spot focus and AF-S? That's what I have typically done and with a tiny bit of care, I have no issue with accurate auto focus. I only use AF-C for situations where my subject is likely to be moving.





(both shot with a DFA *50 on a K-3 III).
01-04-2023, 01:35 PM   #75
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QuoteOriginally posted by Rondec Quote
Why not just use spot focus and AF-S? That's what I have typically done and with a tiny bit of care, I have no issue with accurate auto focus. I only use AF-C for situations where my subject is likely to be moving.





(both shot with a DFA *50 on a K-3 III).
Where did you focus on in the photo with the boy playing chess? His head and his hand are blurry, and it seems the focus plane is on the black pieces on the left side of the board.
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