View Full Version : Most acurate focus for capturing a dog running toward you
[shingo]
30th of August 2009 (Sun), 14:18
I have trouble capturing my dog running toward me, I use only the center point and servo focus.
I was using my efs 50-250 is with my canon XSI.
Is there anything else I could do to help focus?
Someone told me to use all the focus point (auto).
I don't think it would help?!?
It's not that it dosen't focus, it's that some picture are out of focus and other are in focus.
I was at F8 1/400
Addicted2Shooting
30th of August 2009 (Sun), 14:21
Autofocus is too slow, you need to have your camera focused at a certain point and when the dog is there snap the picture.
T.D.
30th of August 2009 (Sun), 14:22
AI Servo with center point focus
mxracer535
30th of August 2009 (Sun), 14:23
Your correct with using center point and al servo. Dont use auto focus
I also have an XSI and to be honest, al servo on this camera just isnt always accurate. I shot motocross with it and find that it miss focus some of the time an is kinda slow. The only thing you can you is make sure to keep the center point steady on the subject
PhotosGuy
30th of August 2009 (Sun), 14:44
The only thing you can you is make sure to keep the center point steady on the subject I'd change that to, "The only thing you can you is make sure to keep the center point steady on a contrasty part of the subject"
tdodd
30th of August 2009 (Sun), 14:53
For the best chance of success you want to shoot in good, strong light (sunlight!) with the sun behind you. Use centre point focus only, AI Servo and you'll need to be very accurate with your aim to keep the focus point on a contrasty part of the dog. Aim for the eyes/teeth. An all black dog is a nightmare - the camera needs to see contrast in order to focus.
Use the long end of the lens - 250mm - this will mean you can shoot the dog at longer range, which will reduce the relative speed at which the dog closes distance between you.
In my experience 1/400 is too slow. You may have problems with AF but you probably aslo have problems with blur. I'd be looking to shoot a running dog at 1/800 or faster. f/5.6 should be plenty to keep the dog sharp, if the focus is good enough. Assuming you have bright sunshine then you could shoot at 1/800, f/5.6, 100 ISO. If you bumped the ISO to 200 you could stop down a little, perhaps to f/7.1 for a little more DOF and to give the AF a helping hand. It should also improve lens sharpness a little. You will also be able to nudge the shutter speed up to 1/1000, which should be good enough. If the light isn't full sunshine then you'd be better off bumping the ISO again, to 400, rather than compromising your shutter speed.
Here's an example at 400mm, 1/1000, f/7.1, 800 ISO....
http://lh3.ggpht.com/_4_R8TkwT74w/SnsN-k8JuYI/AAAAAAABI5k/fFDFGHselwA/s800/20090516_170812_7249_LR.jpg
at 400mm, 1/1250, f/8, 800 ISO....
http://lh3.ggpht.com/_4_R8TkwT74w/SnsONF2PkPI/AAAAAAABI5s/Zcmke3O6Kgs/s800/20090420_160200_6933_LR.jpg
sk8ape
3rd of September 2009 (Thu), 15:16
Awesome explanation!
AxxisPhoto
3rd of September 2009 (Thu), 15:18
AI Servo with center point focus
+1. Always worked well on my Rebel XT.
gjl711
3rd of September 2009 (Thu), 15:26
;8550210']It's not that it dosen't focus, it's that some picture are out of focus and other are in focus. Thats normal. Not all pics are going to be perfect. Take bunches of pics and choose the best.
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