A bit more on the 40D and TCs...

[Keith Reeder]

Evenin' all.

Influenced by suggestions on other photography forums, I went out for a couple of hours this afternoon for another try with the 40D + 100-400mm + 1.4 TC.

Other folk have found that they can get usable AF as long as they keep away from the centre AF point, and I was interested to test this out. So with the Canon 1.4x plugged in, I hit the beach and local harbour.

And d'you know what?

It works.

It's still not as good as the 30D, but - once I got used to looking at the right AF point! - it's a million miles better than what I'd been getting using the centre AF point.

Images today were clearly softer than I get without the TC, but I reckon they're OK - 40D shots seem to sharpen up very nicely anyway - and I'm happy now that the 1.4x is worth carrying along "just in case".

I haven't tried the Kenko 1.4x yet, but that'll be next.

[Saphire]

Thanks Keith, I have given that a try with my 400, f5.6 but I found it a bit awkward to get used to, so haven't tried it since, I will give it another go and see how I get on.

[GYRob]

the shots look very good looks like your on a winner here.
Rob.

[John N]

I would be over the moon if I had taken those photos Keith.

[hollis_f]

Other folk have found that they can get usable AF as long as they keep away from the centre AF point, and I was interested to test this out.
Rats! I wish I'd remembered that when I went out to do some experiementing yesterday. I only used the central point.

I tried my 40D with a Teleplus 1.5x and a Sigma 1.4x (taped pin) converter. Both AFed OK with my first subject - a Little Grebe only about 6m away. It's when I tried stuff that was further out that I found the two behaved quite differently. Even very high contrast subjects (e.g. Mute Swan standing on mud) refused to AF with the Sigma TC. The Teleplus had no problems - even handling flying gulls.

Checking the images at home I could see little difference in IQ of the Dabchick pics.

Next weekend I'll try both again - and a Canon 1.4x and 2x - and I'll see if swapping focus points makes a difference.

[David Smith]

Evenin' all.

once I got used to looking at the right AF point! - it's a million miles better than what I'd been getting using the centre AF point.

I haven't tried the Kenko 1.4x yet, but that'll be next.

Keith
I will show my ignorance now but!
If you don't use the central focus point how come the camera doesn't focus on the back-ground instead of the bird?

[Keith Reeder]

Hi David,

by pre-selecting another AF point instead of the central one and using it in the same way - that is, placing it on the bird and triggering AF - it's much the same in usage terms as the central point.

Admittedly it takes a little bit of getting used to - especially if you're panning with a running sanderling! - but it isn't so different really.

I've been intending to try alternative AF points anyway as a compositional aid - that's what they're there, and Mark Wilson (MW Aurora) does that to great effect - and on the strength of this little flirtation I can see me getting into the habit.