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10-07-2007, 08:23 AM   #1
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K10 auto focus issues

I was shooting some vault competition shots yesterday and they were terrible! I don't have samples to show since I shot them for another photographer, but I will explain the problem.

I was using the 50 mm 1.4 set @ 1.4 and ISO 800, SS 750 to stop the action. Okay, no drag, that part was fine, but the auto focus kept picking up everything BUT the person I was trying to follow. I had the dial turned to AFC to catch the continuous action, but it still insisted on focusing on the objects int he background that were being still.

Any suggestions on how to fix this for the next event? I am just sick about he way the majority of these images turned out! It's true, some were good, but the majority had to be deleted.

Thanks for your help anyone,

Misty

10-07-2007, 08:38 AM   #2
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QuoteOriginally posted by strictlypentax Quote
Any suggestions on how to fix this
How did you have the AF set? "Auto" (where the camera picks the AF point) or "Centre spot"? If "Auto", then you can't control which part of the frame the camera will choose. If "Centre spot", then you have to point the camera very accurately if you want it to focus on a small target.

So for quick moving targets, especially small ones, AF is not infallible, by any means.

If you're trying to catch someone vaulting over something fixed, then the point you want sharp is pretty predictable, so you could switch to MF and prefocus on the point you want.
10-07-2007, 08:42 AM   #3
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QuoteOriginally posted by strictlypentax Quote
I was shooting some vault competition shots yesterday and they were terrible! I don't have samples to show since I shot them for another photographer, but I will explain the problem.

I was using the 50 mm 1.4 set @ 1.4 and ISO 800, SS 750 to stop the action. Okay, no drag, that part was fine, but the auto focus kept picking up everything BUT the person I was trying to follow. I had the dial turned to AFC to catch the continuous action, but it still insisted on focusing on the objects int he background that were being still.

Any suggestions on how to fix this for the next event? I am just sick about he way the majority of these images turned out! It's true, some were good, but the majority had to be deleted.

Thanks for your help anyone,

Misty
You might want to read the following thread on this forum: https://www.pentaxforums.com/forums/pentax-dslr-discussion/12638-learning-sho...on-pentax.html
Succez

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10-07-2007, 08:44 AM   #4
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On the K10 there is a dial on the front that has MF, AFC, and AFS. I have lost my manual, and haven't had time to go download another yet, but I think I remember that means Manual Focus, Auto Focus Continuous, and Auto Focus Spot. I had it set to AFC.

I tried manual focus, but I am EXTREMELY un experienced in using manual focus, so it didn't work for me. Another problem with setting a point of the manual focus is that I have to move my camera as they spring into the air and I have no clue how far out of fram they are going to go. KWIM? Or perhaps I'm not understanding clearly what you were trying to tell me.

10-07-2007, 08:53 AM   #5
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bymy, sorry I didn't see your post until after I posted mine. I read the thread you suggested (thank you very much for sending me there) and I see the general concenses is to use manual focus. I am going to see if it is possible for me to go shoot some of their practice events before I go to another competition.

Thanks for helping!!!
10-07-2007, 12:07 PM   #6
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Suggesting MF as a workaround should be a shame to Pentax. AFC is very poor compared to others like the D80 and XTi. I hope Pentax is listening. I wonder if back/front focus could be making it worse.
10-07-2007, 12:09 PM   #7
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It helps to be acustomed to the lens you are using and how it reacts to spot focusing. I notice that some of my lenses tend to focus high so when I am shooting wildlife with my 70-300 I aim a bit above the subject for the best autofocus results while my 28 and 50mm primes both are spot on and can be aimed directly at the subject center for the best results.Check it out and see how your lens gets it's best focus. It is also important for the subject to take up a reasonable amount of the screen as the small the subject the less chance of keeping a good focus.Perhaps a longer lens would make for better shots.
If you switch to manuel focus you can alway set a shutter trap there by saving time when shooting fast action.Still you will need to know where your best focus is for the lens you are using.
Mostly no matter the way you go, to get the best results you need to spend time regularly with the camera in your hand shooting. After all you can shoot as many shots as needed to get the feel properly. Every day is best. Shoot anything moving . Cars, kids on bikes,kids running about, dogs and cats, birds and clouds. It will all help you to get better with shooting moving subjects.
Best of luck on your next go around.
Kenn
10-07-2007, 06:12 PM   #8
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The other suggestion made earlier in the thread was to set the auto-focus on the center point, rather than multi-point AF. This should help you track your subject.

10-08-2007, 08:54 AM   #9
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QuoteOriginally posted by strictlypentax Quote
I was shooting some vault competition shots yesterday and they were terrible! I don't have samples to show since I shot them for another photographer, but I will explain the problem.

I was using the 50 mm 1.4 set @ 1.4 and ISO 800, SS 750 to stop the action. Okay, no drag, that part was fine, but the auto focus kept picking up everything BUT the person I was trying to follow. I had the dial turned to AFC to catch the continuous action, but it still insisted on focusing on the objects int he background that were being still.

Any suggestions on how to fix this for the next event? I am just sick about he way the majority of these images turned out! It's true, some were good, but the majority had to be deleted.
Pentax does some things very well, but action photography isn't one of them. Poor AF performance with fast moving subjects, and poor AF performance in low light are shortcomings of the Pentax system. I struggled with this for a couple of years, using all of the tricks suggested, including resorting to manual focus. There is simply no way to get a high percentage of focused shots using AF with a fast moving subject.

Recently I sold my Pentax digital system and switched to Nikon. With a D80 body and a Nikkor 70-200mm f2.8 AF-S VR lens, I get about 98% of the shots in focus. From my son's daylight soccer games to the kids running around in the dark, it does it all. It is fantastic! If you are serious about this type of photography, then ultimately you are better off with a mid to high end Canon or Nikon system.

Some suggestions for you to try in the meantime:

Stop down to at least f2.8 to get more depth of field. You will have to use ISO 1600 and then apply noise reduction in post-processing. The ISO 1600 performance of the K10D isn't very good. If you have a 6 MP camera then 1600 isn't too bad and you could even go to 3200. Also note that the 6 MP cameras have even slower AF than the K10D.

Forget AF-C: it just won't track the subject and your shutter trips without proper focus. Use AF-S. It will give you fewer shots, but a higher percentage of them in focus. Use the center AF sensor only and keep it dead center on your subject. Perhaps it isn't the best composition, but you can crop a bit in post-processing.

Try to avoid the subject moving directly towards you or away from you. Try to get sideways motion and pan. I know that this is an inferior angle to get the expression on the athletes' faces, but even moving to 45 degree off axis will help with the focus problem.

You can manually pre-focus on where the action will be and then shoot at the decisive moment. This may work pretty well with a fixed piece of gymnastics equipment like the vault or bars, especially if you increase your depth of field.

The 50mm lenses lack both SDM focusing and immediate manual override. An SDM lens like the DA* 50-135mm f/2.8 will give faster AF focusing and immediate manual override which are both useful. Pentax has a DA* 55mn f/1.4 listed on the future product "roadmap" but who know when (if ever) it will be available.

Last edited by GaryML; 10-08-2007 at 08:59 AM.
10-09-2007, 04:48 AM   #10
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Thanks for all the suggestions everyone. I'm going to try to shoot during their practices and apply some of the things you have mentioned here.

Garry,

I have shot soccer with my Pentax and a Promaster 18-200 lens before with SUPERB quality, in color, focus, and ability to stop action, so for the outdoor stuff I am satisfied with my Pentax. It's the low light stuff that is giving me so much trouble.

I just don't know if I want to invest in another camera, new lenses etc. I am shooting this for another photographer, so if she is not satisfied, she can always tell me she doesn't need me to shoot anymore, but I know if it were me, I would not be satisfied! It's not worth it to shoot four more meets @ 10 bucks an hour to go buy all new stuff, when for my business, my Pentax is perfectly suitable (for now anyway ).

If I reach a point that I need to think of switching, I'll certainly call on you to help me figure out what to buy

Thanks so much everyone for the advice.
10-09-2007, 08:48 AM   #11
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QuoteOriginally posted by strictlypentax Quote

Garry,

I have shot soccer with my Pentax and a Promaster 18-200 lens before with SUPERB quality, in color, focus, and ability to stop action, so for the outdoor stuff I am satisfied with my Pentax. It's the low light stuff that is giving me so much trouble.

I just don't know if I want to invest in another camera, new lenses etc. I am shooting this for another photographer, so if she is not satisfied, she can always tell me she doesn't need me to shoot anymore, but I know if it were me, I would not be satisfied! It's not worth it to shoot four more meets @ 10 bucks an hour to go buy all new stuff, when for my business, my Pentax is perfectly suitable (for now anyway ).
It is certainly not cost-effective to switch brands. I think I did pretty well in selling my newer Pentax gear, but I still only recovered about 75-80% of what I paid. (I still have my LX film camera and my manual focus fixed focal length lenses.) From a pure financial point of view, it wasn't a good deal. It wouldn't make financial sense to invest in new gear just for your gymnastics job.
10-09-2007, 09:04 AM   #12
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QuoteOriginally posted by strictlypentax Quote
On the K10 there is a dial on the front that has MF, AFC, and AFS. I have lost my manual, and haven't had time to go download another yet, but I think I remember that means Manual Focus, Auto Focus Continuous, and Auto Focus Spot. I had it set to AFC.

I tried manual focus, but I am EXTREMELY un experienced in using manual focus, so it didn't work for me. Another problem with setting a point of the manual focus is that I have to move my camera as they spring into the air and I have no clue how far out of fram they are going to go. KWIM? Or perhaps I'm not understanding clearly what you were trying to tell me.
i think you are looking at the wrong "dial".

On the back of the K10D there is a switch where you can set the autofocus point! You have 3 options, automatic, where it can pick any one of the sensors, manual where you can pick the autofocus sensor, or spot, which will autofocus on the center of the frame.

You need to be on the center spot, and also make sure that you have decoupled the function which links AF and metering, I am not sure which of these would have priority.

You would I think want to focus continually as the subject is moving, or focus manually at the point where you want the subject sharp. (timing this can be tricky)
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