Which camera?

Hi I'm going to a horse trials this weekend and not sure which camera would better to take, 40d with 70-200 f4 is or my 6d . Will the 6d be up for the job.

I'd take the 6D for sure! It's better in every way.

What about the 40D would make you think it would be better?

I suppose it's slightly faster 6.5 frames , not so concerned about that , it was more about the focus , I've always used the 40d in a1 servo . I have only had the 6d for a week or so and I don't know how it will perform in a1 servo compared to the 40d . I only use center focus point.

Your 40D will reward you with some very good images - it is "Old technology" but none the worst for that. However your 6D is simply better in every way, except for frames per second. At reasonable to fairly silly ISO the 6D produces some of the best images going.
I love the 40D but compared to the 6D it is a no brainer. Use the center AF point for best results with the 6D and when you have used it a few times put the 40D up for sale - you won't be using it!

I have 70-200F4L lens to share between 5D and 500D.
It is clear choice for me, which one to use.
500D for greater distances, 5D for portrait range.

Is there a reason you don't think the 6D will meet your needs? Some people like to say the outer focus points on the 6D are not up to snuff, but that is a bunch of hogwash IMHO. And you specifically mention that you usually use center focus point, that point is better than anything the 40D has.
If you are too concerned, just take the 40D as a back up in case you don't like the first few shots with the 6D, but I am going to bet the 40D never leaves your bag.

That's good to hear from u guys really looking forward to putting the 6d through its paces this weekend and see what it can do , paired with my 70-200 f4 is I should get some cracking photos.
There's so much crap being said about the 6d focusing, I started to believe it ,I'm going to go out and take some real life photos and find out for myself.

If the photos are for personal use, the 6D is the one to use as you won't get to know it well without using it. If, however, you need to get some cannot-be-done-again images, there may be some wisdom in using a tool you know well, trust, and can get the job done with (as long as it does the job it needs to do).

If you need extra reach take the 40d along
It will give you a slight adavntage over cropping

omer wrote in post #17064553
If you need extra reach take the 40d along
It will give you a slight adavntage over cropping

Not much of one really, and once you realize the ISO and sharpness advantages the 6D has over the 40D, that 2Mpx resolution difference of cropped vs 40D goes away, IMO. Add a Kenko 1.4x to the 70-200 (of course that makes it an f5.6 lens) and any advantage is completely eliminated resolution-wise, despite the loss in 1 stop shutter speeds. The 6D would be 2+ stops better than the 40D to begin with, so one extra stop in ISO to get the shutter speed back is more than sufficient.