Hi guys
PhotosGuy. You may be right, but as I know just a tad more than nothing, and no-one told me, that's the way I went, and it seems to work, for me at least. I always suggest try it and see, then try a different method and eventually you'll find what works best for you. And this is only for chasing fast jets around the sky 
FatAlbert, the TC has just arrived, and fitted to the 5D with the 100-400mm. Works fine, and will AF, but min aperture becomes f/6.7-8 and I'll let you know how much it affects the AF. They do say in the paperwork that it will be slower, but not how much. I guess a day at the airport is called for.
Happy snapping, Chris


