Anybody else struggle with continuous focus?

Alec Malbon

Alec Malbon

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Hi, I shoot at a couple of football tournaments and can never get the best out of my continuous focusing. I use a nikon d300 with a 70-300mm lens. I try the continuous focus mode but end up missing more shots than i get, and usually end up switching to a fixed focal point and predicting where the action will go. This always gives better results but doesn't seem right. Any advice please?
 
When you say continuous focusing do you mean AF-C with single focus point or a small focus point group? Which 70-300 do you have. I previuosly used a Nikon 70-300 vr lens for football a few years back, it was ok in good light but struggled more in poor light. It wasn't the fastest lens to focus, I noticed a big difference moving to a 70-200 f2.8. I use continuous focus all of the time for wildlife. I've not had many problems, not all images in a burst come out in perfect focus but the majority do. AF-C should give much better results than focusing on a point and waiting for the action to come to that point.
 
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Alec, have you tried back button focus (BBF)? Not sure how to set it on a Nikon as I shoot Canon.
 
Alec Malbon said:
No I haven't, is this where I focus off of a separate button to my shutter?
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The d300 should have a dedicated AF-ON button on the back. It should be able to be set up in the menu and turn off the shutter button af function. Is part of the problem trying to track subjects whilst half depressing the shutter and then fully depressing the shutter to take the image?
 
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I've had a D300 for over 7 years and once I found out about bbf I've never looked back and the body is very rarely off of af-c. I've shot BSB, WSB motogp, BTCC, WTCC and my dogs and there's not much more difficult to track than a Westie and never had a problem. I did own a 70-300 VR when I bought my first DSLR but sold it on without using it on the D300.
 
Have you got a sample and the exif data, could it be shutter speed or depth of field thats your problem ? i used to use a D300 professionally for motocross racing and never really had any issues and i dont use back button focus, I still have it as my back up body. I did only really use it with a 70-200 f2.8 though
 
I would guess the lens is the biggest factor... it's not particularly fast to focus, and it isn't particularly sharp/contrasty. If it's also a low light/low contrast situation, that will make it worse.
BBF isn't really going to improve AF functionality at all, the only thing it does is prevent you from interrupting the AF tracking by over-releasing the shutter button.
 
Agreed that the lens will be the limiting factor. If you can, try an up to date 2.8 lens like a 70-200, 300 or a 400. You'll instantly see how much faster the lens snaps into focus. From my Canon experience, even moving from a Mk1 70-200 2.8 to a Mk2 yielded significantly faster and much more reliable focus.

Also I recommend you use centre point focusing only, so you are in control of what the camera focuses on, and you "just" need to place the point on the subject and you're sorted. If you use focus areas, then the camera is guessing what you want to focus on and can often get it wrong.
 
Tobers said:
Agreed that the lens will be the limiting factor. If you can, try an up to date 2.8 lens like a 70-200, 300 or a 400. You'll instantly see how much faster the lens snaps into focus. From my Canon experience, even moving from a Mk1 70-200 2.8 to a Mk2 yielded significantly faster and much more reliable focus.

Also I recommend you use centre point focusing only, so you are in control of what the camera focuses on, and you "just" need to place the point on the subject and you're sorted. If you use focus areas, then the camera is guessing what you want to focus on and can often get it wrong.
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The only issue with this is that with fast moving things you only need the space between say a players legs or if they are carrying a rugby ball the space between their arm and body to drift into your centre point and the camera will refocus on whats behind potentially dropping the player out of focus
 
jamesev said:
The only issue with this is that with fast moving things you only need the space between say a players legs or if they are carrying a rugby ball the space between their arm and body to drift into your centre point and the camera will refocus on whats behind potentially dropping the player out of focus
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You'll find that if you acquire focus on the player, and your camera's follow-focus algorithm is accurate, it will stay locked reliably, providing your own tracking is good enough. Occasionally I used left/right expansion points to allow for the issue you raise, but I suspect the OPs camera doesn't have that functionality. Additionally you can set the camera's propensity to shift focus to allow for momentary drift or a player/referee momentarily coming between you and the subject (again not sure of the OPs camera does this).
 
Tobers said:
You'll find that if you acquire focus on the player, and your camera's follow-focus algorithm is accurate, it will stay locked reliably, providing your own tracking is good enough. Occasionally I used left/right expansion points to allow for the issue you raise, but I suspect the OPs camera doesn't have that functionality. Additionally you can set the camera's propensity to shift focus to allow for momentary drift or a player/referee momentarily coming between you and the subject (again not sure of the OPs camera does this).
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what camera / lens config do you use?
 
sk66 said:
BBF isn't really going to improve AF functionality at all…
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Really?
sk66 said:
…the only thing it does is prevent you from interrupting the AF tracking by over-releasing the shutter button.
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That's the idea!

What ever the used lens, there will be an improvement
but it will not rock a consumer lens among the pro ones!
 
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Kodiak Qc said:
What ever the used lens, there will be an improvement
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It's only "an improvement" if you tend to have issues with interrupting AF. And BBF can introduce the tendency for "jabbing" the shutter release which is a negative.
I only use BBF when I want to be able to switch between AF-C/AF-S/M instantly, which isn't very often... I normally have AF enabled on the shutter release (Nikons will not AF with a remote if it's not enabled).
 
sk66 said:
It's only "an improvement" if
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Yes, right. I set it up and saved it in the shooting menu bank
that I use for wildlife works… and only then.
 
sk66 said:
It's only "an improvement" if you tend to have issues with interrupting AF. And BBF can introduce the tendency for "jabbing" the shutter release which is a negative.
I only use BBF when I want to be able to switch between AF-C/AF-S/M instantly, which isn't very often... I normally have AF enabled on the shutter release (Nikons will not AF with a remote if it's not enabled).
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I tend to use it what I want a single point focus point centred but not wanting the subject in that focus point to be the determining focus of the composition.
 
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