For Kris

[Vapour01]

No really, I'm dying to know if I'll be pleased with the reach of my 300 mm at Brussels.

300 is fine, I used it for two years without any real trouble, I got the 400 for it's far better quality more than the extra 100mm.

Were you using the converter with the 300mm?

Nope, before I got the 400 I was using an 80-200 with a converter and before that a 75-300 (no converter with that, obviously!).

Apologies, i thought you had a 300mm prime previously. Does the AF pack up if you try to use a 75-300 with a TC?

I'd imagine so, but I never tried it because the quality loss would be terrible.

[Omag 2.0]

The converter would make you loose 2 f-stops of light + loss of imagequality, not to mention that you'll have to focus manually.

Over at Belgium digital they claim that teleconverters are basically only interesting on primelenses.

[Vapour01]

Prime Lenses often don't work (well) with converters either. The 300 F4L IS didn't work well with the Canon 1.4x extender (focus horribly slow and inaccurate) and my 400 only work with the Kenko 1.5x I had for the 80-200, the Canon extender (if i had one still) wouldn't allow for auto focus.