AF-C Shooting + Composition

Sol · 6 Mar 2007 at 07:49

Bit of a strange question regarding auto focus fun with a nikon d70. If I set it to AF-C shooting for moving targets..i.e. animals then I am pretty much forced to use the central focus point because it is the strongest of the lot.

Is there a decent way of doing this but allowing some recomposing? Normally you hold the shutter button half way and it tracks the target but then a completely central subject is obviously not desirable all the time. Do you just use the other focus points and make do?

robertgilbert86 · 6 Mar 2007 at 08:41

Have you tired it with the other focus points?

SteveOBHave · 6 Mar 2007 at 08:55

Yeah there shouldn't be any reason why the central focal point should be any stronger than the rest. Practice practice practice.

rpstewart · 6 Mar 2007 at 09:09

SteveOBHave said:
Yeah there shouldn't be any reason why the central focal point should be any stronger than the rest. Practice practice practice.

It's normal for the centre point, or a group of points in the centre of the focussing array to be more sensitive or be cross type sensors which work well in either orientation. I'm not sure about the Nikon but on my body (1D MkII) the centre 9 points of the AF grid are high sensitivity ones.

Spuds · 6 Mar 2007 at 09:13

Their should be an AF lock button above the D-Pad, I think it's labeled 'AE-L/AF-L'. You might need to adjust the settings for it so that it only lock focus rather than focus and exposure or just exposure depending on what it's currently set to

robertgilbert86 · 6 Mar 2007 at 13:02

Now I've thought about it I've used AF-C for sports photography (football, hockey) and I mostly used the bottom AF point, and it was fine. You shouldn't have any trouble as long as you keep that focus point over the subject.

Using the bottom AF point, aiming at the ground by the subject's feet, the subject should be in focus where-ever it is in the frame.

hoodmeister · 6 Mar 2007 at 13:07

rpstewart said:
It's normal for the centre point, or a group of points in the centre of the focussing array to be more sensitive or be cross type sensors which work well in either orientation. I'm not sure about the Nikon but on my body (1D MkII) the centre 9 points of the AF grid are high sensitivity ones.

Truth.

The centre AF point is a cross type, the other four are single line.

Read this. While it doesn't relate directly to tracking moving targets, it will help you garner a better general understanding of the autofocus system on your D70.

Joe T · 6 Mar 2007 at 19:00

Ive managed to track ok with the bottom AF point.

Sol · 7 Mar 2007 at 05:17

Fair enough, I've used the other focus points before it's just that the centre point is the only square one on the d70, the rest just cover either horizontal or vertical axis.

I am not having problems with it, just wondered if there were any useful tips regarding using the continuous focus and re-composing.

I prefer using the half hold, re-compose, then shoot technique and obviously if you use that in the AF-C mode then you'll lose focus on the intended part. I'll just use other focus points.

jhmaeng · 7 Mar 2007 at 22:37

Or, you can remap the AE-Lock button to become AF-On.

So, in this case, you would use the AE-Lock button to track the focus, and the shutter release would be purely for releasing the shutter. You're able to recompose because once you've set the focus using AE-Lock, you can let go of AE-Lock and then the focus will be fixed. You then recompose and press the shutter release, which will release the shutter without touching the AF.

It's in the custom menu somewhere.

In fact, the D200 and models above it all have a separate AF-On button purely for this reason - to allow you to separate the focus process with the shutter release.

Sol · 8 Mar 2007 at 01:53

Cool I'll maybe give it a go. I never use the exposure lock button really so it can't hurt to give it a try.

I'll be in Hong Kong on Sunday so was tempted to do a wee upgrade to the D200, only the warranty rubbish is putting me off. Gonna buy a 70-200 VR lens too if the price is right.

FranchiseJuan · 8 Mar 2007 at 11:30

I would also like to add (maybe you already know this), but recomposing is a very bad habit to get into. If you are shooting at a shallow DOF, then you will not get correct focus on the subject you wanted.

If you do then use the seperate AF and shutter button option and recompose, you will not only loose correct focus due to the subject maybe moving while recomposing, but also from the recomposing itself.

SDK^ · 8 Mar 2007 at 12:49

FranchiseJuan said:
I would also like to add (maybe you already know this), but recomposing is a very bad habit to get into. If you are shooting at a shallow DOF, then you will not get correct focus on the subject you wanted.

This is true but you will offer suffer an out of focus image if you are shooting and recomposing with a wide angle lens and a wide aperture. Generally speaking focus and recompose will still produce sharp subjects.