Problem acquiring focus

cdmazoff wrote:

hotdog321 wrote:

cdmazoff wrote:

Hi.. I have been getting some really great shots with my new lens (100-400mm II plus 1.4x III) (See most recent entries in my photostream at flickr)..

But often when the light is glaring or there are moving bushes etc... the autofocus just won't latch on.

Yesterday it was with a hummer way up in the glare, today a red-wing BlkBrd on a tree branch that swayed and behind that was open water and trees across the water. The autofocus wanted the trees in the background. I tried everything and gave up

I am using evaluative metering and 9 point AF.. 9 Point AF seems to be more reliable than single point.

I don't take off the teleconverter. I assume that the AF would probably work much better if I did, but I need the distance.

Any tips?

Thanks

CD

I can think of a couple of issues. One is that you are riding at the edge of the f/8 autofocus limit by combining the 1.4X with your 100-400 II. It should still work under good light, but that brings us to the second issue. When you shoot against glare or haze or low light the autofocus has a harder time locking focus.

About the only suggestions I can make are:

1. remove any filters

2. try a single point focus

3. use a lens hood

4. you might need to switch over to manual focus under rotten light.

Good luck!

Thanks to all of you for your advice. Craig, :

1. I don't use any filters,

2. I am trying single point when 9 point won't work,

3. I ALWAYS use a lens hood,

4. and I'm now going to go out and experiment with the AF switch and single shot. I'm always shooting AI Servo because I do birds and they twitch

Sounds like you really know what you are doing. I think you may need to go "old school" manual focus if it still acts up. Happy "hunting!"