Focus Setting Question

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n2desilv

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Noel
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Hi ya,

Have a question that's been bothering me, so I figured I'd ask here. I have a Nikon D90, so the terminology will be from a Nikon point of view.


As I understand it (and correct me if I'm wrong), the AF-S is for single focus shooting, you should a focus point and the focusing will only ever evalute that chosen point. This mode is to be used for staionary/non-moving objects.
AF-C is for continous focusing, so if a subject moves out of the chosen focus ponit, the camera will use the surrounding focus points to track the subject; so this is used for moving subjects.

My question is, is it fine to use AF-C for stationary objects, will the focus be just as sharp? :shrug: If it is, then why bother having the AF-A mode (Camera detect whether subject is still/moving and changes focus to AF-S or AF-C). :bang:

Would appreciate your thoughts and comments on this. Also would appreciate what focus settings you tend to use.

Cheers
 
AF-C will work if you just point and shoot but not if you focus and recompose. If you do want the best of both then you can try back button focusing with AF-C. I find AF-A a bit random.
 
There are 2 sides to focusing.

Should it focus just once or constantly. AF-S is it focuses once, AF-C is it constantly focuses, MF is you do it yourself. AF-S and AF-C focus using what you tell it to focus with.

What should it use to focus. Single Point will use a single point that you select. Dynamic Area will see which are in focus and show you how many are in use by highlighting all that are in focus. Then there is 3D tracking which will allow you to choose a subject using a single point and then recompose, it will then refocus if needed using whichever focus point is on the subject you chose.

AF-Area

http://imaging.nikon.com/history/basics/16/02.htm

Focus-Mode

http://imaging.nikon.com/history/basics/16/03.htm
 
terryt said:
If you do want the best of both then you can try back button focusing with AF-C. I find AF-A a bit random.
Click to expand...

Hi Terryt, could you explain this a bit more please. Are you saying you set the focusing to AF-S and when you want to you press an assigned button to switch to AF-C? Do you have to repress to switch back to AF-S?
 
You can use continous focusing, but its not as quick and not as accurate.

In my personal opinion, I virtually only ever use AF-S, because its so much more accurate, if you have the skill and decent lenses, even with fast moving subjects.

Paul.
www.photographybyriddell.co.uk
 
n2desilv said:
Hi Terryt, could you explain this a bit more please. Are you saying you set the focusing to AF-S and when you want to you press an assigned button to switch to AF-C? Do you have to repress to switch back to AF-S?
Click to expand...

You set it to AF-C but rather than using the shutter half press to focus you use the AE-L/AF-L button to focus. Check out this thread. Explains it a lot better than I ever could :lol:
 
Never released you could use AF-S for recomposing. Used to do this with the old point and shoot cameras, but thought it was a limitation on SLRs. Used to get me frustrated with the d90 (only 11 focusing points).

Assume, though with this method you need to use a slightly smaller apperture to nail the focus exactly where you want it (rather tha f1.4 or f2 for example)?

Haven't had a chance to play with back button focussing but looking forward to testing this out.
 
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