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Old Aug 10, 2009, 8:02 AM   #1
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Default On the Pitch with the K-7

I have had sensational service out of my K20, but felt it failed me in times I needed fast, precise autofocus. Thus, I couldn't wait to test my new K-7 on a sports field. Sunday morning, I went out to the park where the Hispanic men's league plays. I used the Bigma since I had the luxury of loads and loads of light.




I cannot make a fair comparison with the Canon or Nikon autofocus systems since I haven't used them for sports, but what I can conclude is that the focus system is a HUGE improvement--both faster and more precise. I wound up rejecting only a small number of photos because of poor focus. (We won't talk about how many I rejected because of compositional questions--players backs turned, no ball in photo, etc. I was definitely out of practice.)




I was shooting mostly at f/11.0 because of the bright sun and kept the shutter speed high. Perhaps the most telling point about the AF system was the fact that when I shot in burst mode, all shots in the burst would retain their focus when I did my job (keep the proper focus point). The shots above had only minimal cropping for compositional purposes. There were a couple that I cropped a little more heavily for action in front of the goal.




The real test will come under the lights with my Sigma 70-200 f/2.8 HSM. I'll be real interested to see what happens with football.

Paul

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Old Aug 10, 2009, 8:27 AM   #2
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Glad you are liking the K-7 and that there is a noticeable performance gain.

Seems to have done a good job with these shots and your eye is not that far out at all

I'm intrigued why you chose f11 as getting a more narrow dof would have given these some more punch and allowed some better freezing of action by getting the shutter speed up.
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Old Aug 10, 2009, 10:48 AM   #3
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Glad to hear that you are having better results with the K7. I don't shoot sports much, and the only long lens I have is manual focus, so I have no experience with this type of thing. From what I found at the fair, I'm not surprised at your impressions. Are you going to try larger apertures as you get more confident with the focusing?
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Old Aug 10, 2009, 4:31 PM   #4
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Yes Paul, I'm definitely looking forward to your results when you use a wider aperture. F11 is a very generous aperture for grading AF accuracy. I'll be looking forward to your shots at f2.8. Still, it does sound encouraging so far!!
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Old Aug 10, 2009, 8:03 PM   #5
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Quote:
Originally Posted by Mark1616 View Post
I'm intrigued why you chose f11 as getting a more narrow dof would have given these some more punch and allowed some better freezing of action by getting the shutter speed up.
Mark, I chose f/11 because the Bigma's DOF is so razor-thin at full extension, I was afraid that it wouldn't give me enough DOF to have two players in-focus inside a frame. I agree with both you and John that it probably was, in John's word "generous," to run a test with that much DOF, and when I use the Bigma again for sports, I will probably give it a run at about f/8.0 (f/6.7 is max ap at full extension).

My plan initially had been to shoot the second half of one match with the Bigma and the first half of the next match with the 70-200, opening up its aperture. However, the second match got off to somewhat a late start, and when I realized what time it was, I thought discretion would argue for my heading for the house, since I had slipped out without telling my wife I was headed for a pitch. I shot about ten minutes with the 70-200mm @ f/4.0, but the run of play wasn't on my side. This one was cropped to 1579 X 1897 before being resized for the forum.

Paul
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Old Aug 10, 2009, 8:39 PM   #6
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Hi Paul,

I don't know how well it'll work under the lights, but my guess is that the K-7 will be at least satisfactory. I don't have any specific data, but my impression is that its AF is not as fast as the higher level Canons and Nikons, but for me, it's easily good enough for my purposes, and I need pretty good AF performance because my eyesight can vary so much during the course of a day. Another factor for me is that the K-7 points better than any of my other bodies. I'd taken to regularly using a Red Dot Sight with the K20 to get my birds in the VF faster, but I seem to have less need for this with the K-7. This gives me more time to focus, so the improvement in AF speed might be exaggerated for me.

I am also finding that at least my copy of this body is considerably more accurate in locking focus, especially on distant objects.

Below, I've uploaded an example of what I'm talking about concerning accuracy at distance. Of course, the 14.6 MPs helped here. . .

This is a snapshot of a couple of doves on a dead tree at probably about 75-100 feet and a 947x677 pixel (about 2/3 MP) crop of the one bird which has been PP'd to taste. I took this just to get an approximate focus at this distance as I had planned to try shooting Barn and Tree Swallows in flight at about this range and wanted to give the AF a head start. . . but the Swallows, which had been all over the place previously, vacated soon after I had gotten the camera out, so I didn't get any shots of them. . .

I hope that you're liking your K-7 as much as I'm liking mine. . .

Scott
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Old Aug 10, 2009, 10:12 PM   #7
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Paul, I don't know how long you were with the Bigma with these shots but if you were at 500mm and keeping up with that action you and the k-7 did real well.

I'm glad to hear so many reports of fast auto focus as I struggle with my K100 to focus on fast moving subjects.

I find that I need to zoom out and acquire the subject and then zoom in try and stay with it until I get the action of the subject that I want and then fire off the shot. Then the slow mirror action causes me to lose acquisition of the subject and I need to repeat the zoom out zoom in action all over again.

I am trying to be patient and wait a little longer before I pull the trigger on this camera. I don't give my patience much longer!

Nice series and a nice report.

Lou
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Old Aug 11, 2009, 12:45 AM   #8
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Paul, I don't know how long you were with the Bigma with these shots but if you were at 500mm and keeping up with that action you and the k-7 did real well.
Lou,

You bring up a very valid point, and one I had not actually checked. With that much zoom, and a fast moving sport, I was constantly adjusting the zoom. I went back to the EXIF's and checked, and found, there was more variance than I realized. The focal lengths were:

1- 160mm
2- 270mm
3- 270mm
4- 138mm
5- 360mm
6- 420mm

The last two...with the 70-200...were both at the full 200mm. My biggest surprise in checking the initial six postings was to find that images 5 & 6...the two at the greatest distance...and which required heavy cropping...were not at the full extension of the zoom.

Paul
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Old Aug 11, 2009, 3:50 AM   #9
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Morning Paul. Personally when shooting field sports I shoot with the widest aperture possible so even when using my 120-300 f2.8 with a 1.4x TC I go for f4 at 420mm. Honestly this will give a much more pleasing shot with the background much less distracting. As you don't have a constant aperture lens when using the Bigma and assuming you are not shooting in Av then I would set the aperture at the 50mm setting to allow the aperture to open more when wide than when long. I would then set the ISO based on the long end so you have your desired speed and go with that.

If you don't do that then as in the examples here you will have had f11 at settings like 138 and 160mm.

This will obviously mean a few less keepers but the ones you do keep will be much stronger photos. As I already said you did a good job with these but you have the kit to take it up a level so go for it.
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