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10-16-2012, 09:58 AM   #1
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Problem with focusing

Hi there. I found out my action shots never work out well.
I would really like to know what I'm doing wrong and what I can do about it.
My camera: Pentax K-5
Lenses: Sigma 70-200mm f2.8 EX DG OS HSM and Tamron SP AF 90mm f2.8 Di Macro

To demonstrate what I mean, I will place some examples (pictures with moving dogs).


^ 1/200s - f2.8
90mm (Tamron lens)



^ 1/500s - f3.2
90mm (Tamron lens)



^ 1/250s - f2.8
200mm (Sigma lens)



^ 1/640s - f2.8
158mm (Sigma lens)



^ 1/320s - f2.8
128mm (Sigma lens)



^ 1/500s - f2.8
70mm (sigma lens)


As you can see, the focus is on the ground (grass) instead of the dog. Can somebody tell me how I would get the focus on the dog? What do I do wrong?

Thanks in advance!

10-16-2012, 10:30 AM   #2
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did you turn off the camera stabilizer...when using the os it does the stabilizing in the lens...i also just noticed you are using 2.8...that is a very narrow DOF and for the moving dogs you really need to set it higher (imo)...also you didn't mention what kind of focus format are you using
i guess i need to pay attention to your complete message ...i see you are also using the tamron...have you checked the calibration on the lens
10-16-2012, 10:55 AM   #3
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Are you using auto focus, or Catch in Focus? If so, the answer is really, really simple. Auto focus sets itself to where your subject is located, the mirror flips up, the shutter opens and closes. The problem is, by the time your shutter opens, your subject is no longer where your camera set focus. I ran into the same problem shooting my own dog a couple months ago. Okay, that sounds bad, but you know what I mean.

You might be able to solve the issue with Live View and continuous focusing - somebody else can comment on that. But I'm a viewfinder kind of guy, especially in bright light. So I dropped back on my old experience-

Manual focus to a spot ahead of your subject, wait until your subject almost but not quite reaches your pre-focused spot and trip the shutter. The 'not quite' time frame is to accommodate the mirror and shutter lag time.
10-16-2012, 10:59 AM   #4
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The grass just behind the dogs appears to always be in focus and sharp. The problem is probably that the dogs are moving. Did you try using AF-C? Maybe you have backfocusing issues though, try that out with a test and then adjust AF fine tuning for that lens.

10-16-2012, 11:17 AM   #5
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As pearsaab stated, DOF is certainly one factor. There are alot of discussion threads on this forum regarding DOF and acceptable sharpness and there are online calculators to help you understand the distances. Slow your aperture to 5.6-8 or more and see what results you get, Regarding AF, assuming that you are using 11 point AF, try switching to center AF. The Pentax 5 and 11 point AF system will sometimes lock onto unintended areas of high contrast that are not what you intended to focus on. Keep in mind that the center AF area is much larger than the red square that you see in the view finder. It looks like the next to the last photo of the pit bull is a DOF problem due to the wide open aperture. The last photo looks like your AF picked a spot on the road.
You probably already know this, but for action shots, don't forget to take advantage of that 7 fps burst mode!
10-16-2012, 11:21 AM   #6
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QuoteOriginally posted by Mikado Quote
Hi there. I found out my action shots never work out well.
I would really like to know what I'm doing wrong and what I can do about it.
My camera: Pentax K-5
Lenses: Sigma 70-200mm f2.8 EX DG OS HSM and Tamron SP AF 90mm f2.8 Di Macro

To demonstrate what I mean, I will place some examples (pictures with moving dogs).


^ 1/200s - f2.8
90mm (Tamron lens)



^ 1/500s - f3.2
90mm (Tamron lens)



^ 1/250s - f2.8
200mm (Sigma lens)



^ 1/640s - f2.8
158mm (Sigma lens)



^ 1/320s - f2.8
128mm (Sigma lens)



^ 1/500s - f2.8
70mm (sigma lens)


As you can see, the focus is on the ground (grass) instead of the dog. Can somebody tell me how I would get the focus on the dog? What do I do wrong?

Thanks in advance!
I am going to take a stab at this and say you likely got the camera in the "automatically" choose the focus point. If so, change it to "user" select, and then put the red spot that is in your view finder in a place you would likely want to be in focus. My wife likels the middle but I like to vary it.
You also have a very shallow depth of field according to the information attached to the photos.
boost your F stop to around 4-5.6, depending how far away you are. see if that makes a difference. If the shutter speed goes to slow, then boost your ISO up... you have lots of room with your K5
let us know how you make out

randy
10-16-2012, 01:58 PM   #7
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- First of all, don't use the widest apperture but rather something around 8-11 if possible. That is to increse the depth of focus/field.
- Second, as with sports games, you need a fast shutter speed to freeze the movement. To enable this, set your "film sensitivity", ISO, to above normal (say 800- 3200). The K-5 handles this really well.
- Third, you have the luxury of continuous auto-focus (AF.C, you find it at your left hand thumb). Even if it is not the best with the K-5, it should do.
10-17-2012, 03:46 AM   #8
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Pentax cameras do not have predictive AF so photos like this there will be back focus. If want to take these photos I would choose Nikon than Pentax...

10-17-2012, 04:27 AM   #9
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Wow Jippo, great advice: "leave this forum and buy other gear"
I've seen plenty of photos of wildlife and moving targets done with Pentax, with great sharpness and perfect focus. Every photographer just has to learn to use their gear to the fullest.
10-17-2012, 05:10 AM   #10
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QuoteOriginally posted by 123jippo Quote
If want to take these photos I would choose Nikon than Pentax...
Why did you join a Pentax forum? I have to tell you, I shoot Pentax and I shoot birds in flight with that Pentax, and I have no problem with getting them in focus. But then again, I shoot all manual with my Pentax K-x, using faster shutter speeds over 1/800s, and aperture is usually set at f8 or f11 to get more detail in the feathers. So, jippo, if you've never used a Pentax DSLR, I'd suggest you buy one and try it out, you'd be amazed at the details you can get shooting moving objects.
10-17-2012, 07:56 AM   #11
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QuoteOriginally posted by 123jippo Quote
Pentax cameras do not have predictive AF so photos like this there will be back focus. If want to take these photos I would choose Nikon than Pentax...
are you really, really sure? I know the PZ-1 did, it was also tied into the power zoom lenses and image size tracking.
10-18-2012, 03:04 PM   #12
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The challenge in this type of photography (moving objects) remains, regardless of camera brand. It is about the photographers ability to choose proper exposure settings and focusing technique. Any point-and-shoot camera in knowing hands could have delivered focused images of the lovely dogs...
10-18-2012, 03:47 PM   #13
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QuoteOriginally posted by jmarkku Quote
- First of all, don't use the widest apperture but rather something around 8-11 if possible. That is to increse the depth of focus/field.
- Second, as with sports games, you need a fast shutter speed to freeze the movement. To enable this, set your "film sensitivity", ISO, to above normal (say 800- 3200). The K-5 handles this really well.
- Third, you have the luxury of continuous auto-focus (AF.C, you find it at your left hand thumb). Even if it is not the best with the K-5, it should do.
+1. I use AFC good amount. Coupled with TAv, with ISO limit from 80-10 000, f5.6 or higher and shutter set for 1/320s or more, result in usable images of fast moving subjects, even in poor lighting conditions.

Cheers.
10-19-2012, 01:32 AM   #14
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QuoteOriginally posted by Lowell Goudge Quote
are you really, really sure? I know the PZ-1 did, it was also tied into the power zoom lenses and image size tracking.

really really? no can not say like that cos I not work in Pentax...but thats what I have heard from other Pentax user.
10-19-2012, 02:58 AM   #15
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QuoteOriginally posted by 123jippo Quote
..Inappropriate Post Deleted by Moderator..
Take cover...NOW.

Last edited by Tom S.; 10-19-2012 at 12:25 PM.
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