400mm/5.6L +1.4x vs. 300/2.8IS L + 2x?

I currently use a 300/2.8L IS with both 1.4x and 2x TCs for BIF with my newly acquired Mk3. I also use a 40D. Focus acquisition with the 300+2x combination has become better with the Mk3 as opposed to the 40D but it's still lacking. A fellow photographer mentioned that I should try the 400 f5.6 + the 1.4x. I realize that I'll lose a full stop and IS... I can probably rent one to try it out but figured I'd ask here on the forum before I go to the expense.

Good idea? Waste of time and money? Look forward to hearing your thoughts...

I use the bare 400 f/5.6 on the Mark III and the 40D/50D; I've not tried it with the 1.4x. It's a very easy lens to hand hold and the lack of IS shouldn't present problems for you if you're photographing BIF in good light. I'll defer to other forum members about the comparison between the 300 f/2.8 + 2x and the 400 f/5.6 + 1.4x.

I have used both lenses with converters but have not compared. Have to guess the 300 2.8 has to have the edge.

What are you going to be using the lens for?

I'm really looking for a lighter (hand-holdable) combo to get to near 600mm for BIF in good light. The 300 + 2x combination is heavier than I'd like for hand-holding, and my 100-400, (not previously mentioned) although very sharp by itself, doesn't handle the 1.4x very well.

I used the 400f/5.6 with a 1.4x TC on my 1D3 and liked the results. My best guess is that the 300f/2.8 and 2x TC might be a bit sharper and maybe faster in AF performance.

Axel -

Thanks for the info! I might rent the 400 later this summer to try it, as I'm sure the weight is more manageable.

Chris,

The 300 2.8 with 2xTc is much faster and a little sharper than the 400 F5.6 + 1.4xTC. No doubt it's the better choice between the two. The 500mm with 1.4x is an even better choice, IMO.

Jim -

Thank you for weighing in on this! I'll start lifting some weights to better manage hand-holding my 300/2.8 +2x combo! I hope to get the 500 someday....

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Thank you for weighing in on this! I'll start lifting some weights to better manage hand-holding my 300/2.8 +2x combo! I hope to get the 500 someday.... <!-- / message -->

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And therein lies the difference. I carry 3 cameras 2X 30D's 1D MKIII, a 70-200, 300mm F4 and a 400 f/5.6 plus convertors and all I need is my Lowpro pack, I use my monopod as a walking stick and can manage all day whilst climbing and walking long distances when you get into the better (and bigger) lenses you come up against the limitations of size and weight.

I am saving my tripod use for when I lose my mobility.:)

Wading in:) Have both and use both, with and w/o TCs on a M111 and enjoy both wouldn't be w/o either. Both fill a need depending on what I'm doing at the time, how's that for an answer;)