Pre Focussing....How please

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nikonuser

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Dave
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I have read a lot and been told many times that at certain sporting events you need to pre focus on a spot to take a really good sharp image, but how do you do that when there is nothing to focus on.
I can understand say, a horse jumping a fence, you can pre focus on the fence, but what do you do if there is nothing to focus on at the point that you want to take the photograph.......do you focus on the ground at that point!!
Thanks
Dave
 
if your going to pre focus on a point then why not place something there ( well beforehand ) to focus on first then remove it before whatever you want to take a picture of gets there. Then make sure your camera is in manual mode so the settings don't alter

Realspeed
 
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You can pre-focus using the hyperfocal distance for your lens. You do this based on what aperture you use - usually f/16 - f/22 to maximise depth of field to get a shot that is in acceptable focus.

For instance on a FF camera using a 50mm lens at aperture f/16 the hyperfocal distance is about 17 feet. So everything form about 8.5 feet and onwards will be in acceptable focus.
 
In the goood old days before Servo AF pre focussing was the norm at sporting events, just pick the spot and focus on that, it doesn't matter if it's the ground or whatever, if you focus at 25ft and shoot a bird 25ft in the air or a horse jumping a fence 6ft up and 25ft away you will get the result you desire. Don't forget to turn the AF off on your camera thoughelse it will try and refocus when you press the shutter ;)
 
nikonuser said:
I have read a lot and been told many times that at certain sporting events you need to pre focus on a spot to take a really good sharp image, but how do you do that when there is nothing to focus on.
I can understand say, a horse jumping a fence, you can pre focus on the fence, but what do you do if there is nothing to focus on at the point that you want to take the photograph.......do you focus on the ground at that point!!
Thanks
Dave
Click to expand...

Pre-focusing tends to be an old technique, from the days of manual focusing and before AF was as good as it is now. Today, most people put the camera on servo-AF and let it track the subject, always keeping it sharp. That way, you can also rattle off a few frames and increase your odds - with no film to pay for. Some cameras/lenses are better at this than others, so use whichever method returns the best hit-rate for the conditions.

If you want to use pre-focusing, then you can usually focus on anything. There's usually a clump of grass to lock on to, or a patch of oil on tarmac. If not, then focus on something else that you estimate to be the same distance away.
 
Thanks Guys, appreciate all your help in clearing up some doubts in my mind
Dave
 
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