Best AF setting

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MarlowTrips

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Jide SObo
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I recently upgraded my Fuji S9500 to a 400D and I'm a bit confused by the AF options. My old fuji had one AF point in the centre of the viewfinder but the 400D has 9! When I try to take a photo I find it quite hard to get the right AF sensor to register.

What is the benefit of having 9 AF sensors over having one?

Is this something I should learn how to control or should I just selct the middle sensor and re-compose, as I'm used to doing with the Fuji?

Thanks in advance for your wise words.
 
Hi Marlow Trips. I reckon your suffering from the same problems with your 400D that you where suffering with your S9500 - GREEN BOX MODE ;) The S9500 actually has an even more adapable focus point selection than the 400D inasmuch that it could be moved further around the screen. The 400D has fixed focus points which can be selected to ensure the camera focuses where you want it to. In GBM the camera will fix a focus where it can get the best chance of achieving focus - which may or may not be in the centre of the shot, and may or may not be where you want it to focus. I suggest you read your manual (page 57).
 
The AF points are there to be used. Of course it's easy to just select the center on, and in some cases that may be the best option.

Don't forget that half pressing the shutter button causes the camera to focus. continue holding the button locks the focus in that position, so you could have all AF points active, move the camera so that the one nearest the point of interest "locks. Whilst maintaining pressure on the button, recompose and shoot.

If you find doing this causes more than on AF point to Lock and the others are not where you want your focus to be, just select the one you need. You've got the control over the camera, but it sometimes takes practice
 
Use one AF point for non-action shots - usually the centre spot but as Gofer says sometimes for composition reasons you may want to enable another single AF spot rather than the centre one when your main subject isn't in the centre of the viewfinder.

Multi-AF spots are for photographing difficult, fast, moving subjects such as birds in flight where regardless of which AF spot(s) attains focus, as you track the bird, and as long as you keep the bird in the active AF spot area, focus is passed seamlessly (hopefully) from one AF spot to another to maintain focus as the bird's position changes slightly in the viewfinder ( In Servo Mode)

Having multi spots selected all the time is no doubt the cause of most of your problems, but it's also important to choose the right focusing method.

ONE SHOT MODE

You'd normally choose this mode for static subjects and you get a nice green focus confirmation light in the viewfinder together with a beep if it's enabled. The problem with this method though is once you have the green light, focus is locked as long you have the shutter button depressed to the halfway position. If you hold onto this position too long while composing your shot, it doesn't take much movement of either yourself and/or the subject to give you an OOF shot.

SERVO MODE.

In this mode the lens focuses on the subject continually regardless of your own or the subject's movement when you keep the shutter button half pressed. although you get no focus confirmation light. It's heavier on battery drain I suspect but this is my preferred focus mode for the vast majority of my shots.

AI SERVO MODE

I dunno if your camera has this mode (my 20D does) but just don't use it - it's absolutely unreliable. It's supposed to be an intelligent system which will select servo or not depending on subject movement but it really is pants.

That's the basic bones of it, but there are plenty of sub settings and personal settings within the AF settings and as Gofer says, there is really no substitute for wading through that manual to get a good understanding... sorry. The manuals are translated into English from Japanese by a guy from Papua New Guinea, but that's just the way it is. ;)
 
CT thanks for that explanation, it was really helpful. Say if you are doing a portrait would you still use SERVO mode?
 
I think I would now without a doubt, providing there's enough light for the AF system to work and it wasn't obviously hunting.

When I was doing wedding groups with a Nikon F4, I used one shot focusing mode, which is when I became aware of the danger of holding onto to that half pressed shutter position just a tad too long. I developed the technique of focusing and composing the shot, then fully releasing the shutter and pressing it again, but carrying on all the way with a smooth action once focus was confirmed. The F4 had Servo Mode but nothing like as quick and reliable as it became on later cameras.
 
I believe that in servo mode Canon's are setup to acquire focus with the centre point initially and then track the subject as it moves around the frame which is something to bear in mind when using all the points in servo mode.

Also, AI servo won't fire unless it has a lock which can be helpful or just plain annoying if it think it doesn't have a lock on the wrong thing :(
 
Good points pxl8. We could go on about this all night, but you really need to understand what the system needs to attain focus and pick your focus spot on the subject intelligently - something with enough contrast to be able to work. If you try focusing on an even one tone subject, i.e. a wall with no detail, you'll run the batteries down and still not get focus.
 
Thanks for asking that question, and thanks for the answers guys. :thumbs:
 
Thanks for your advice guys. :thumbs:

I think I'll try using Servo mode and see how that goes.
 
CT said:
AI SERVO MODE

I dunno if your camera has this mode (my 20D does) but just don't use it - it's absolutely unreliable. It's supposed to be an intelligent system which will select servo or not depending on subject movement but it really is pants.
Click to expand...

aaahhhhhhh, so its not ALL my fault! :clap:

thanks for the explanations from everyone, the manual doesn't quite tell the whole story :thumbs:

there's still hope then that one day I'll get it right
 
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