40d/bushhawk changing the focus point

pecrow

pecrow

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having a few problems with the 40d fitted to a bushhawk. basically, i select centre focus point, use ai servo and high speed burst. i track a moving subject, fire off a burst but find that the camera changes the active focus point to the bottom centre by the end of the burst. i dont touch the controls other than the shutter button on the bushhawk.

does anyone please have any idea what might be happening here as it completely ruined a days shooting?

thanks
 
If you have selected the centre focus point only then the camera will stay on that point regardless of what's going on with the subject.

If you have selected all the focus points the camera will start tracking from the centre point then move to any other point it thinks is going to keep what WAS under the centre point in focus.

I have found the second method to be a bit hit and miss with moving subjects, and whichever method you use it's good to have the focus tracking for a bit before you start shooting to give ther camera a chance to work out what's going on first. Back button focus is the way to go here but takes some getting used to.

Could you give a bit more deatail about what you were photographing and some examples.

Don't forget the focusing point is actually quite a bit larger than the square in the viewfinder, can lead to the camera focusing on something other than your intended target.

HTH

David
 
thanks david

i was out photographing aircraft, unfortunately i dont have the shots to hand. i definitely selected centre focus point so kept that over the jet only to find when reviewing, that the shots taken at the end of the burst had the centre lower focus pont activated. so i ended up with a load of mis-focussed shots. this never happened before and i wonder if its anything to do with the bushhawk connection?
 
That sounds a bit odd, are you using DPP or Zoombrowser to show you the focus point(s) used?

David
 
no, am using the overlay on the camera screen during image review. i agree its weird and very annoying.
 
It sounds like you have the CFn for "Automatic focus point selection" enabled...this will use the centre point to acquire focus and then the surrounding points to track.

Bob
 
sorry if i'm being dense but i cant find that Cfn. can anyone please point me in the right direction?
 
Not being dense, I could not find it either. Don't think this is a function on the 40D other than by selecting all the focus points to start with

If you start out having chosen a single focus point in AI Servo (no matter which one) the camera stays on that point no matter what.

Going back to you being able to see a single changed focus point in the image on the back of the camera I think this means one of two things.

Either you jogged something while taking the sequence of photos, or your 40D has a mind of it's own :thinking:

Have a look at the custom function to change the focus point by the rear control dial, perhaps that what's going on??

HTH

David
 
Willid1 said:
Going back to you being able to see a single changed focus point in the image on the back of the camera I think this means one of two things.

Either you jogged something while taking the sequence of photos, or your 40D has a mind of it's own :thinking:

Have a look at the custom function to change the focus point by the rear control dial, perhaps that what's going on??

HTH

David
Click to expand...

i have the option to change focus points via the joystick enabled but my hands are holding the bushhawk when it changes (so well away from the camera). i think i'll try a full reset to default now.
 
pecrow said:
i have the option to change focus points via the joystick enabled but my hands are holding the bushhawk when it changes (so well away from the camera).
Click to expand...

but my nose isn't :amstupid:
turns out i've been hugging the bushhawk tighter than normal and squashing my nose up against the joystick.......i am so embarrassed.
 
Glad to hear you worked out what it was.

David
 
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