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Forum: Pentax K-1 & K-1 II
10-02-2017, 09:30 AM
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I am writing this post as a summery. I have developed quite a tentious rapport with the K-1 Autofocus system. And I will be leaving this topic for others to contribute to.
So after I had practiced with over 2000 shots to get a good setup, I went hiking with the Pentax K-1. I have to say that the Autofocus, with a moving subject, is just not what you would expect. Within the forest, I got about 10% success. With the lower light in the forests I really needed that lower F-stop value to get the shutter speed a bit higher. I think 2351HD has a good point: The K-1 is great for landscape, probably the best in that category. It will most likely be a tie for portrait shots as well.
I now have read all the Guides (that I could find), including the ones suggested by angerdan. As well as come across posts by biz-engineer (1, 2, 3), who got those amazing mallard shots, and everyone who is honest about the autofocus of the Pentax K-1 (such as Winder), and the conclusion is as follows: Yes you can get great shots of moving subjects, but be prepared to push your DOF larger than you expect. Most common suggestion I found so far is that you need the right setup. It is true that the more you prepare for where the subject is going to be the better your focus success will be. And that there are settings that affect the lag between autofocus and shutter release. But even after all of these considerations, you might be better of with a different camera if you are interested in more action shots. I have totally fallen in love with the K-1 but I think 2351HD has a good point and once I get more into action, I will most likely invest into a Nikon D500 as a second camera (since I have some Nikon glass, and the D500 is comparable to the K-1 in price).
My only critique so far is that there is a lot of woo-woo, and no one really knows what a good setup is. I think I know why. The K-1's autofocus tracking (z-axis) reminds me of Jack White's comment of what kind of guitar he likes to play. He likes fighting a guitar to get the sound he wants out of it. He doesn't like playing easy guitars, because he wants there to be a struggle. For him the struggle encapsulates the artistry, which might be very true for some K-1 users. I think this process gets people to settle on settings and styles that allow them to get the best out of the K-1 (for them), but in the process they have given up on possible shots as well as adopted some woo-woo into their process. It also makes it difficult for them to relay to others what to do, and this is the point of my critique! After scouring many posts for autofocus information I came across a lot of "they don't know how to use the camera" (refering to reviewers), and "do what I do", or "do what he does" (with vague references) and "if you are struggling then it is your fault".
The one nugget I found that gave me some useful information was the post by beholder3 (I found this by following a link by clackers to a post by biz-engineer who referenced this post; This was before angerdan link) on "Guide to Camera and Autofocus Settings for Shooting Sports". The nugget was found in the "Drive Mode and File Format, Image Style" related to turning down the JPG values. While you are checking out that section, note the horse jumping picture right below "Drive Mode and File Format, Image Style". You will find an image that appears to be back focused (if studied closely), but the large DOF hides it. The rider is right where the post is (beholder3 comments that he focuses on the rider's face), yet there is a lot more ground in focus behind the horses rear hooves than in front of the post.
This doesn't mean you cannot find that low F-Stop value shot that is exactly where you want it; I did it! But it takes the right settings, understanding exactly where your target is going to be, and a lot of practice (2000 shots of the same thing) and I got my percentage to 42%. In a real life woodland scenario it dropped down to 10%. And even in the 42% environment my results would drop down to 15% if the light conditions changed. (Back in the woods): I had my wife handle the camera for a while, with a moving subject, and the first thing she complained about (without knowing any of the back story) was that the focus wasn't where she wanted it.
In my opinion there are 3 main issues with the Pentax K-1 Autofocus system. - The first is the introduced delay between autofocus acquisition and shutter release. This is a settings issue that can be resolved with settings listed here and here.
- The second issue is that the AF system is just not that great at z-axis tracking. It hunts quite a bit more than what people expect. With Shutter Release Priority you can see how much it hunts by looking at the first image sequences of this post. I think in Focus-Priority mode it sweeps back and forth and uses the catch in action mechanism to fire the shutter. The more you look at sequences (2500 on my end), this becomes quite obvious when you notice where the missed focus lands. It also makes it unpredictable to know what will be used to determine when the subject is in focus. If it sweeps from the back of the subject, then a contrast line towards the back of the focus point will be used and vise-versa.
- 3D tracking or equivalent mechanism is just not a viable option on the K-1. You can select the feature but it won't do what you hope it will.
I surmise that anyone that gets accuracy levels above 45% is using large DOF to hide the flaws (second part of this post covers that) or the subject isn't moving that fast in the z-axis plane compared to the DOF (this is a common work around, I saw, by shooting the subject from the side).
I don't think it would be helpful to try and obscure these faults. If we can identify them and stress how important they are to the full system, then it allows Pentax to focus on improving these faults in later releases of their products or firmware updates.
For now expect to struggle with the system, and if you really are hoping to get into action shots, you might want to pickup a second camera.
Who knows, a firmware update might resolve all these issues in the future. I keep my fingers crossed.
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Forum: Pentax K-1 & K-1 II
09-26-2017, 02:36 PM
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It would be just for giggles. :) Auto mode is a modified P mode with all the other settings as Auto. Which gives you no control over Aperture, which could hide a lot of the focus problems in the DOF. More on that in a bit. You also have no way to tell the system what to focus on. It automatically picks it's subject.
After doing some more tests I can report that AdobeRGB mode, with PEF, seems to be about the same as sRGB. BUT I didn't get a lot of shots in to make this definitive. With my new test there might even be a possibility that AdobeRGB is a bit better for autofocus than sRGB, but my sRGB shots were a bit worse than my last measurement. That said I had a lot less shots this time (~50 small sample size), where as before I had 110. So I can at least report that AdobeRGB is the same for Autofocus speed delay or better than sRGB.
The one extra measurement I took this time, was measuring the accuracy, if my DOF was half that of the subject's length. The method was to see how close the focus was to the center spot target. If that was less than 1/4 of the subject length, then I counted it. This caused the percentage of in-focus pictures to almost double in count. In one test the percentage went from 18% to 35%, and in another it went from 33% to 50%. I will discus below how this makes it difficult to compare accuracy tests.
So here is another set of system settings that appear to work well:
Menu 1
--Phase Detection AF
----AF Mode: AF.C
----AF Active Area: SEL
----AF.S Setting: Focus Priority
----1st Frame Action in AF.C: Focus-priority
----Action in AF.C Cont.: Focus-priority
----Hold AF Status: Off
Menu 2
--Crop: FF
--Image Capture Settings
----File Format: RAW
----JPEG Recorded Pixels: XS
----JPEG Quality: 1-star
----RAW File Format: PEF
----Color Space: AdobeRGB
--Dynamic Range Settings: All Off
--Noise Recution: All Off
I want to address some of the topics I have become aware of as I have worked on solving the autofocus problem:
The DOF plays a big role in how we asses whether something is in focus. I recently watched this review of the Nikon D850 vs the Nikon D5 focus tracking:
Youtu.be
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src="https://www.youtube.com/embed/AdX8H6YSfZA?controls=1" allowfullscreen>
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Identical setups were used for both the D850 and the D5 and in Matt Granger's tests he found the D5 to be about 90% accurate and the D850 to be about ~65% accurate. Both the D5 and the D850 have the same autofocus system. In my opinion the main difference, is the pixel pitch. The D5 has a pixel pitch of 6.41 µm. And the D850 has a 4.35 µm pixel pitch. That is a very significant difference, and is the main component in assessing the circle of confusion for a camera. The larger the circle of confusion the greater the DOF will be, with everything else being the same. It very well may be that the D5 is an autofocus beast because of it's larger circle of confusion due to larger pixel pitch.
Click here for more on Circle of Confusion
I am highlighting this because I feel it is important to understand how difficult it is to asses the autofocus problems. Especially trying to compare two systems to each other. The Pentax K-1 has a 4.86 µm pixel pitch and the Pentax K-3 II has a 3.88 µm pixel pitch.
A larger circle of confusion is also going to give you a larger DOF, with everything else being the same. If you are hunting for a very shallow DOF then this becomes a consideration. It will also show more focus flaws as your DOF becomes smaller.
I am therefore fully aware that for some people the accuracy will be a lot different depending on your DOF, relative to the speed of your subject towards you.
Some additional notes:
I found the Pentax 70-200 to be back focusing more often from 15 meters and further and then suddenly jump much closer into focus at 10 meters. So pay attention to your focus ring throw, it seems to play a role in how close the focus lands and could be a big culprit in your results on your K-1.
The contrast lines on your subject do play a role. clackers pointed this out before, but in the picture below you can see how the camera chose a different spot than what would be obvious.
The line between the top of the lip and the fur was used and specifically the line at the corner of the mouth.
If you want to measure your center point area, you can follow these steps. The link is to the spot where the method is described:
Solving AF Problems - 8 Common Autofocus Problems - And Their Solutions - YouTube
In my setup I used a softbox with the lights on and a square electrical tape in the center. I took a picture everytime the focus settled. I then stacked the pictures and drew red lines to include a piece of the electrical tape from the side I approached it. Then each layer was set to 25% opacity and I got the following result:
The blue box is an action I created to draw it onto the image. I can run the action at anytime to see where the center spot was. You can duplicate this for all your focus spot. You will notice that a lot of the spots are not where they indicate in the view finder.
It will also be useful to make sure your lenses are fined tuned to your camera. I used the Dot-Tune method and this video gives you instructions. On the Pentax camera you will be looking for the Diamond in the bottom left of the view finder. When lit it will indicate detected focus.
You Tube
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For most of my lenses I found this to be great. But for one lens it ended up front focusing, and I had to repeat the process. So take sample pictures with different setups to make sure the focus is where you expect it to be.
I hope this is useful for anyone trying to diagnose their own issues.
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Forum: Pentax K-1 & K-1 II
09-21-2017, 05:08 PM
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Yes it is just SEL. And I have compared SEL vs Center point and they are the same. The only difference is that with SEL you can move which sensor you would like to use. I haven't tried different sensors other than the center one at this point. But from what I know, the best sensor is the center one.
When I have time I will experiment a bit more. I might want to map out all my sensor locations at one stage. So far I have just done the center one.
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Forum: Pentax K-1 & K-1 II
09-21-2017, 04:26 PM
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Eureka!
With some new settings I now get 33% accuracy with Phase Detection AF set to Auto for 1st Frame Action and Auto for Action in AF.C Cont. This was out of a 109 shots.
With the new settings I get 41.8% accuracy with everything set to Focus Priority. This was out of 43 shots (the dog was done playing).
Here are the 41.8% accuracy settings:
Menu 1
--Phase Detection AF
----AF Mode: AF.C
----AF Active Area: SEL
----AF.S Setting: Focus Priority
----1st Frame Action in AF.C: Focus-priority
----Action in AF.C Cont.: Focus-priority
----Hold AF Status: Off
Menu 2
--Crop: FF
--Image Capture Settings
----File Format: RAW
----JPEG Recorded Pixels: XS
----JPEG Quality: 1-star
----RAW File Format: PEF
----Color Space: sRGB
--Dynamic Range Settings: All Off
--Noise Recution: All Off
With these settings I got this shot:
The nose is out of focus, the eyes are in focus and then by the time you get to the ears they are out of focus again. Very shallow depth of field. I got a total of 3 of these with very shallow DOF, placed exactly centered.
With the higher hit accuracy I can now notice that the Pentax 70-200 lens is also lagging at further distances and is more dead on at about 15 to 4 meters.
Thank you for everyone who provided some input. Sure Nikon and Cannon might have better Autofocus systems on the flagships, but I can live with 41%.
Who knows, there might be more to squeeze out in the future.
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Forum: Pentax K-1 & K-1 II
09-21-2017, 02:25 PM
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Exactly! At this point I surmise that you are spot on! I am leaning more and more towards the idea that people who are finding the autofocus tracking as super fast and accurate in the Z-axis, are most likely masking the significant delay (unbeknownst to them) with a large enough DOF. The shots like the cyclist by clackers, could be a luck shot, OR he might have some really good setup or technique. Since it is a one off, at this stage, I cannot pin point to how that shot came to be. I am not so confident that my shooting style is the problem, because after measuring my center spot area, I found that the most contrast areas were on the front of the dog within the area, and that if the focus was picking up the background, then the grass would be in focus much further behind the dog than what it is.
From my calculations at f/2.8 my DOF at 20 meters was 1.6 meters. Which is more than the dog, yet the focus wasn't encapsulating the whole dog, just the rear and the grass behind him. At f/4 it would be 2.2 meters, which might have been enough to bring the head into focus. At f/5.6 the DOF is 3.2 meters, and f/8 it is 4.6 meters.
What I have uncovered is that some settings do play a role in the length of that delay. And I think this delay is the key to the problem that people are experiencing. I think the autofocus method and mechanism of the camera is most likely great (with focus priority), since the results are consistently off. I hope I can identify the settings that can decrease this delay. So far the biggest one is JPEG.
Thank you Winder! Your earlier reply (a few days ago), made me at least realize I wasn't going crazy. And I have to thank clackers because he inspired me to go do more tests.
I probably would never dip far below f/4 on the 70-200 lens at 200mm. You loose a lot of sharpness below f/4 in the corners. But there are those rare shots where you want focus on a small area with sharpness right in the center.
For those that are not aware of what the issue is (since we are several posts in since this was brought up):
Here are pictures with low f-stop values from other camera manufacturers (These are 2008 and 2009 cameras).
Owl in flight
Arabian Horse
Running for a meal | Mabry Campbell Photography mabrycampbel? | Mabry Campbell |
The last one is a horse running towards the camera for a snack. You can see how the head is completely in focus and by the neck the focus has dropped off. In an attempt to duplicate a similar result, with over 900 shots, I got two shots with these kind of result.
Other Testers have found similar issues:
Pentax K-1 Review: The Best Landscape Camera Ever? - YouTube - You will hear their mention of the tracking (although it seems they are buffer hounds).
Special K? Pentax K-1 Review: Digital Photography Review
Winder also pointed this out.
Here is an example of me attempting to get the same kinds of shots:
https://www.flickr.com/gp/153388317@N08/7m3701
You will notice that some of the shots are at f/6.3 and yet I don't have focus on the target. It was the first couple of shots that highlighted the problem to me. I started tweaking settings and got some improvements.
I am planning on testing catch in focus, to see what results it yields.
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Forum: Pentax K-1 & K-1 II
09-21-2017, 10:31 AM
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So I measured my Center Spot location and created an Action in PS to place it on the picture. I don't have new pictures, so I am using some of the pictures from before to give examples of where the center spot is.
You will see quite a few contrast lines, which should be enough for the phase detection, within the center spot. I flipped the images to Black and White to show the contrast lines.
Here is one of the first pictures I shared in this thread:
Here is a side by side of the brown dog. There is less contrast lines between his ears and tail than between his nose and eyes. There is a another strong contrast line between the Frisbee and his chest and nose.
But I agree: it is a variable that should be removed from the equation. I will try to setup a more reliable test method to make sure there are no problems related to my shooting style.
Winder thank you for that information. I mentioned above that I am shooting at f/2.8 on purpose. I agree that I can get excellent pictures at f/8. What I am attempting to do is find the best settings for autofocus, for a target moving towards me. This will give me more choices, so that I may select lower F-stop values and trade that for better ISO values and shutter speed values. The 1/5000 choice was just based on the ISO range and brightness at f/2.8 that day. The f/2.8 is a deliberate choice, since it will highlight any flaws in the autofocus system. Furthermore, I would like the option to separate the face of the dog from the background and its body. I noticed a lot of suggestions to increase the DOF.
I am experiencing a lot of focus issues. There are other people that echo my findings. Then on the other hand there are people that experience no autofocus problems. Like clackers, and biz-engineer. In some of their pictures I find large DOFs (which is great if that is what they wanted, but if there are any autofocus flaws in those shots then I can't discern it).
To highlight the autofocus success and failures we need a shallow DOF, compared to the target, so we can find where the autofocus lands. We also need shot sequences to be able to see if there are misses by the autofocus. biz-engineer seems to cover a lot of those bases, but we cannot see where the focus really lands since the whole target is in focus.
So why are some people finding the autofocus lacking and other don't?
I am attempting to isolate the variables, which is difficult because I have only one pentax camera and one 70-200 lens. I am attempting a more scientific approach to the solution, which requires identifying the variables. biz-engineer and clackers might have a better version of the K-1 than what I have, or better lenses than what I have. Those are very possible variables. They might also have a better shooting style or better settings.
To figure this out, I am trying different settings to identify and eliminate variables. I am trying to avoid the woohoo effect where we feel like X and Y is the solution, and instead be more empirical with the results. It is frustrating and tedious on my part, since I am noticing a lot of woohoo, and testing other's settings with no observable change (I do need a better setup to retrieve more empirical results).
A common woohoo I have heard is: Person X didn't know what they were doing and that is why they had bad results with autofocus. I find this doubtful when people who have a lot of camera experience (NOT ME, Other testers) suddenly consistently get bad autofocus results with a pentax. Questions I have are: what settings did they get wrong? what did they need to do differently in their style, that is different from other camera manufacturers? If the solution is a larger DOF, does that really mean the autofocus of the pentax is on par with other camera manufacturers? I want to know as many true things and as few false things as possible. I have no bone to pick here, just a drive for getting the most out of my K-1 and lenses.
I will be working on a better rig to eliminate my shooting style. If I find the best settings for the autofocus system, and I am still experience problems, then the only possibility is that my lens or camera, or both are not on par with what biz-enginner or clackers'. At that stage I might rent another K-1 and a lens and do the same tests and see what I get. Maybe biz-enginner and clackers have exceptional versions of the camera or lenses. Or they actually have similar focusing issues but have been able to overcome the problem with style and DOF tuning. If you go back to the sequence of shots with JPEG and Focus-Priority you will see that the focus is almost exactly on the face, for many of the shots. So yes, a larger DOF would hide this problem completely.
I hope this highlights how many variables are at play, and so far I have found that RAW(DNG) is a factor in the delay, at least in my camera, between autofocus and shutter release. This could be related to the embedded jpeg in the DNG file, or all RAW files have this issue. But I need to do more tests to determine this. But for now I need to take a break (while I travel) and it will take some time to build a rig to test autofocus and eliminate my shooting style as a factor. I am hoping with a rig that runs at a constant speed, I can actually measure the delays and location of the focus more accurately. This will allow for much more precise determination of which factors play an actual role in getting the best autofocus results.
I apologize if anyone is frustrated by my posts. I truly do value any input, which would lead me to get better results and identify more variables.
Thank you!
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Forum: Pentax K-1 & K-1 II
09-20-2017, 02:51 PM
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I am posting this as a separate post to keep previous content intact, so that those that read this at a later date may follow the bread crumbs and potentially find possible solutions.
Some new test results:
I selected 4 sets of dog runs with the following settings:
Pentax K1, Pentax 70-200 at 200mm f/2.8. Shutter speed 1/5000 using TAv. File type JPEG. Focus-Priority On. Shake Reduction on. On a tripod. Each Sequence held between 12 to 15 pictures. The average accuracy of the test was 41.15%.
The next test was with another 4 sets of dog runs and a Pentax K1, Pentax 70-200 at 200mm f/2.8. Shutter speed 1/5000 using TAv. File type JPEG. Release-Priority On. Shake Reduction on. On a tripod. Each Sequence held between 13 to 18 pictures. The average accuracy of the test was 23.47%
I determined that the focus was accurate if I found the face of the dog completely in focus. The truth is that some of the shots were still back or front focus in some of the results, even though the face was completely in focus.
I would like to duplicate the Focus-Priority tests again with RAW files, to make sure that I have consistent tests to reference. I would also like to test Full Manual mode as well.
I surmise at this stage: that the best method for action shots is to use JPEG as a file format with Focus-Priority.
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Forum: Pentax K-1 & K-1 II
09-20-2017, 11:45 AM
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Clackers inspired me to go do more tests. And I have some interesting results.
Again the setup is 70-200 fixed to 200mm and f/2.8. Everything is off, SR, NR, etc. The idea isn’t to get the best picture but to see where the focus lands.
I had an inspiration to test two settings more extensively. The first is to go to Release-Priority on the camera and see if things improve. What I found was that the autofocus is still not very accurate but you now have a new feature that does land you some good shots, once in a while. The jumping focus is now back. Generally the focus starts behind the target and then passes the target. At this point you have a shot at getting a picture right on where you want the focus, if the firing of the shutter is on the spot. The next step is that the autofocus detects the front focus and either stalls the progression or reverses the focus direction. At this stage the focal range passes through your target again and you can yet again have a possibility of a picture you would like. It might cycle through this several times but once in a while it will settle on your target for a few shots, and then it will loose it again.
The picture sequence below demonstrates this (I have several similar sequences):
In picture 7 it appears as if we have a dead on hit, but the focus is actually mid body of the dog. In picture 10 through 13 we have dead on hits. The focus then falls behind again, from frame 14 to 15. So the in focus shots is 4 out of 15. Which is a lot better than my previous method. There might be something to say about the lens’ ability for fine control at the further distances. The amount of movement on the focus ring from 10 meters to infinity is really small and this could be a culprit. But keep in mind the focus is lost again at frame 14 and 15. So the lens could still be a very viable culprit at this point.
And then I did a second test. This time I switched to JPEG. My thinking was that the JPEG compression algorithms are well established and many dedicated CPUs have built-in pipelines for JPEG compression. Maybe this would free up the CPU and the buffer. I was back to Focus Priority and 200mm with f/2.8.
JPEG with Focus Priority Sequence:
This time it was 7/ 15 of the pictures that were dead on target, and the other missed ones were really close! And with quite a few of the frames the target was far away, which shows that the Focus Ring throw range hypothesis, from above, is most likely not the culprit. If this is the better method for action shots, then it would be up to the photographer to decide if they want to abandon their 14 bit depth of field for 8 bits and have all their settings baked into their file.
I will try to head out again and get some more shots with the two different methods to see if there is truly something to these methods.
I am not willing to kill my dog for my hobby, so this takes time. :)
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Forum: Pentax K-1 & K-1 II
09-20-2017, 06:48 AM
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Thank you for that information clackers. If you wouldn't mind sharing your autofocus settings, I would greatly appreciate it.
From this image:
I gathered the following information from this picture:
Focal Length: 140mm
F-Stop: 4.5
Runner Height: ~1.5m
Distance from runner: ~20m
With those settings I calculate your DOF to be 5.3m
What I am really curious about is this picture:
Do you have a sequence of these pictures? And do you have the RAW files available? I would love to be able to track the focus through a sequence of shots.
The other possibility that comes back at this stage, is the potential of the lens being a factor. I have the Pentax 70-200 and you are using the Tamron 70-200, which is something I mentioned before as not being able to rule out.
One more question, do you shoot RAW or JPEG? It just popped into my head that this might be some sort of contributor, if it is CPU ralated.
Thank you clackers, I hope you don't mind sharing your setup. It might help me figure out how to improve my setup.
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Forum: Pentax K-1 & K-1 II
09-19-2017, 11:03 PM
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Thank you, clackers.
I am excited to see these pictures. I noticed that you had a massive DOF.
Just a guess, but I would say the F-stop is between 7.1 to 9.
I have researched some pictures of birds in flight, last night, and focused quite a bit on those flying towards the camera, or away from the camera. One thing I noticed is that the pentax cameras consistently had to have a significantly higher F-Stop values.
I also located this research by DPReview: Special K? Pentax K-1 Review: Digital Photography Review
I have been able to locate more information on what the problem is. The issue is the lag time between autofocus acquisition and shutter release. This link has actual measurements of the problem: Pentax K-1 Review - Performance
Here are some sample pictures of 2008 cameras shooting at low F-Stops, being able to achieve this:
flight | The Cattle Egret for me are te fastest flyers.They ? | Flickr
Owl in flight | While visiting a bird show, this owl came fl? | Flickr
And here are some pentax equivalent pictures:
Flight | Phil Morgan | Flickr
_IMG7380. 300 mm. 1-1000 sec at f - 8,0. ISO 100. 0 EV | Flickr
One great shot I found of a K-1 was this one: The bird was about to land, so very little forward speed. By my calculations the bird was between 20 and 25 meters away and the DOF was about 1.1 meters. I wonder if there was a nest below the bird and he just setup the focus before hand (which is one of my ideas as a work around).
Undercarriage Down! | Peter Wood | Flickr
I agree, you can get magnificent shots with a large DOF. And it is an effective way to overcome this flaw. I was hoping to get some nice action shots with some great separation between the subject and background.
For those hoping to take shots of someone walking towards them, with low F-Stop values, they will be quite frustrated. I am sure it is a rare scenario and you can always just start pushing the F-stop value higher until you get what you want. But it is helpful to know why you need to do so.
I am still happy with my K-1, but I wish it didn't have this limitation.
For bird pictures, on a bright day, there really is no difference, since the distance between the background and the subject would yield similar results with the higher F-stop values. But it does eat away from the available shutter speed and ISO combinations, you could have had.
Thank you everyone, for your input. I didn't know what the problem was at first, since it manifested it self in some very strange ways. I can now live with it, now that I know what the issue is. I think I have a few workarounds for different situations.
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Forum: Pentax K-1 & K-1 II
09-18-2017, 07:35 PM
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Forum: Pentax K-1 & K-1 II
09-18-2017, 05:05 PM
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Thank you for replying.
The only two things I noticed, that is different between my approach and your setup, is the tripod and the lens. Everything else I do, is the same as yours or I have at least tried extensively. I did several shots without the SR while on the tripod and I notice the difference in the effect, but there is no difference in the Autofocus results, but I would like to dedicate a whole session towards this, since I can increase shutter speed and see if I get better results. So the SR item will go back on the todo list.
I still don't understand what the tripod would change. I am really trying to isolate the variables here, so excuse my ignorance. I have read the other AF posts and a lot of the information is great, but some of it is interwoven with some serious woohoo. If we can identify the variables then we can isolate for them and try to figure out what is a good setup.
I would love to see how your 300/4 lens does with someone running towards you at f/4.5. I haven't been able to isolate the lens as a culprit in this situation and I would greatly appreciate any tests you can do with your setup. Pictures would be great!
So far I surmise that the problem is a delay after autofocus acquisition and before shutter firing. I am thinking of maybe building a testing rig that would allow me to measure the delay in a much more controlled manner. Then I could quantify the different features more accurately and see what works best. But that will take time to build.
I have to admit, my heart sank when I noticed $400 to $800 cameras (from 2008) out performing, in the autofocus scenario, compared to my K-1 setup.
Thank you!
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Forum: Pentax K-1 & K-1 II
09-18-2017, 12:27 PM
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I am using AFC with back button AF down and keeping the spot on the head. I will do short bursts of shutter on continuous shooting while holding down the back AF button.
The tripod is to reduce any shake on my side while I am tracking. A lot of people in wild life photography will recommend a tripod for these kinds of setups. Could you enlighten me as to why you think a tripod should not be used?
Have you attempted anything similar to what I have done (target moving towards you or away), with better results? I would love to know, it could be a problem with my setup. What are your AF settings?
Thank you!
Jeff
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Forum: Pentax K-1 & K-1 II
09-18-2017, 09:49 AM
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Another 390 shots down, with some new information.
33 AF is a no go. The closest object isn't always the target that is selected. And now that I go through a small thought experiment, that wouldn't make sense either. The grass in the fore ground, would be the closest and would be the object focused on the most, if that method was true. What I did find with the 33 AF point focus, is that the focus was all over the place, until the dogs were real close and took up most of the area. But the system was still plagued by an issue that I will discuss in a bit.
The settings I found to work the best so far:
Menu 1:
--Phase Detection AF:
----AF Mode: AF.C
----AF Active Area: Spot or SEL (BUT NOT SEL S, SEL M, or SEL L)
----AF.S Setting : Focus-priority
----1st Frame Action in AF.C: Focus-priority
----Action in AF.C Cont.: Focus-priority
----Hold AF Status: Off
--Contrast Detection AF
----Contrast AF: Spot (Bottom one)
----Focus Peaking: Peak On (doesn't matter for this)
----Contrast AF Options: Focus-priority
I read in some of the discussions that AE Metering might help in focus detection. In my tests so far it plays no role of any kind. In the 390 shots, I tried different values of the AE meter, and found no difference, in fact the AE spot meter might be better (not based on tests), since less area is evaluated in making the calculations for exposure. My next test session will be completely manual instead of TAv, which might have a role to play in what I discuss below.
The other item mentioned, was that the 70-200 lens might be too slow to keep up with the dogs. This might be true, but I am very doubtful of this, since the lens can go from infinity focus to 2 meters in under a second. The Hyper focal distance being 347 meters in my setup, would mean the lens can go from 347 meters out to 2 meters in under a second, which is faster than the dogs.
With the setup above I was starting to get some better shots, but there was a more consistent issue that plagued the setup the whole time. Here is what I was able to surmise as the problem:
The autofocus is actually spot on most of the time, but there is a significant delay between the autofocus acquiring a target and the timing of the shutter. This was made evident with sequences such as below. Watch the focus travel from the tail of the dog to the face of the dog as the dog transitions from jogging to laying down.
Some additional considerations to take into account: The dog was not running fast at all. This would be the pace of a slow jogger at the time that the sequence started.
I need to take another sequence of shots where I go completely Manual to determine where the issue is. But I can already state that someone walking towards you with the aperture wide open (small DOF) will result in very poor results.
So to summarize what I am experiencing:
The autofocus is dead on target most of the time (95%), but the delay between focus acquisition and shutter firing is too slow to keep up with an object moving towards you, unless you go to a big DOF. There were a few focus jumping events but it was much better than before.
All shots were on a tripod and I did try shots with Shake Reduction off and on. So far I like the Shake Reduction on with tracking some of the targets. It helped remove motion blur with tracking targets at 1/1600. BUT I want to do a more definitive test with just this feature.
I also want to do tests with all the NR features off as well as the Highlight and Shadow corrections off. They should only be in effect after the image is in the buffer, but I will try testing this.
For all those that find the Autofocus fast, you might be correct, but the issue might be the time delay of the shutter firing. I would love to see if anyone else can replicate what I have found, since it could just be my setup.
I welcome any input on what I might want to consider, the next time I head out.
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Forum: Pentax K-1 & K-1 II
09-17-2017, 06:44 AM
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I will give those options a try. My only concern with the 33 AF points, is that the focus won't be on the dog but somewhere else.
I will do another test this week with some different settings.
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Forum: Pentax K-1 & K-1 II
09-16-2017, 01:30 PM
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I am a recent owner of a K-1 and find the Autofocus quite lacking. For still shots it is easy to use focus peaking in live view and get excellent results, but I found the following conditions to be too much for the K-1: dark color tones (in bright light), moving targets (with central spot auto focus in AFC).
K-1 firmware 1.41.
I use AF.C with back button focus and Central Spot and Focus Priority in the following examples (the red lines indicate the in focus plane). I placed the Central Spot on the Dog's faces (right between the eyes):
With dark color tones you just don't know what you will get. It most commonly is front focus or back focus but almost never on target.
Here is a nice high contrast subject, a white dog with a black snout running towards me. This was the only shot in focus of any of the dogs running towards me. The focus is right on target, maybe a bit front focus..
Here is a brown dog as the subject, running towards me. With the light conditions there should be enough contrast, especially with the Frisbee. But instead we get back focus. This is an example of most of the shots.
With 240 shots I got 4 in focus shots. One with a dog running towards me (the one above) and 1 of them running at 90 degrees to me. Two of the shots was with the dogs moving around each other and having high contrast between the two dogs.
With the brown dog as a moving target, here is some focus jumping sequences:
I find with the dogs, setting the spot on their heads, that I generally get back focus as they run towards me. It made me think that the auto focus is slow. The one in focus shot I got, might be a fortunate focus jump that just happens to get the right spot.
You can review some of the images yourself:
https://www.flickr.com/gp/153388317@N08/3515LG
In summation I would say there is a good likely hood of slow autofocus, or at least a significant delay between autofocus and shutter time. And I find random autofocus jumps that just don't make sense.
If anyone has any insight, I would really appreciate it!
As a landscape camera it is great! Really awesome pictures!
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