Super Tele Choice

I owned the Canon 300 f2.8 IS that I used with the 1.4xII extender. Later I upgraded to the 300 f2.8 IS II lens.
The most important benefit I found was how much better the new lens worked with extenders (using the 1.4xIII and 2xIII).
Sharpness, contrast, and AF speed was improved. The lens also has improved IS and is less weight than the original.

It's an option to consider, but very expensive.

Both my extenders are Canon mkIi versions that were current when i picked up my 300L and would still be ok with the newer lenses, but obviously mkIII extenders be better for version II tells.
It's not reach I'm after per se, it's improved image quality. I can get to 300 or 400mm very easily with tcons even with just the 200L. But like i said its the siren call of two scintillating primes over the one holy grail of the 400
Lots to think about, thanks everyone for your input guys, this is nice problem to have and I'm looking forward to whatever decision i make

bildeb0rg wrote in post #18755779
Both my extenders are Canon mkIi versions that were current when i picked up my 300L and would still be ok with the newer lenses, but obviously mkIII extenders be better for version II tells.
It's not reach I'm after per se, it's improved image quality. I can get to 300 or 400mm very easily with tcons even with just the 200L. But like i said its the siren call of two scintillating primes over the one holy grail of the 400
Lots to think about, thanks everyone for your input guys, this is nice problem to have and I'm looking forward to whatever decision i make

Only the 2x III is worth the upgrade for IQ. The 1.4x III is only worth the upgrade to get better AF speed, I believe, from what I had read.

That matches my experience too.

My "upgrade" from the 1.4 Mk2 to the Mk3 was not noticeable in AF performance or IQ. However the 2 x Mk3 gave markedly better IQ than my Mk2 and, I think, better AF. Note this was not on IS Mk2 lenses - they were the 300 F2.8 L IS and 600 F4 L IS. The 2 x Mk2 was simply useless on the 600 IMO. The 2 x Mk3 certainly isn't!

1.4III won't give you any worthwhile advantage now (with 1D4).
Down the track it gives faster AF and also more AF points depending on body and lens.

The current 400mm DO II is a sweet piece of glass. Takes both extenders really well. The 1.4x III does not miss a beat. The 2x III is great for static subjects but a little slow for fast movement. The weight and size is very nice. I both mine from Canon Refurb. I used it last year in Costa Rica with the 1.4x glued to it, it performed excellent.

I've thought about the 400DO a few times and always baulked at the f4 aperture. If im going exotic i may as well buy the fastest lens available and tbh the weight saving isn't an issue for me as im nearly always shooting from a monopod. Good to know it takes converters well tho and glad you're enjoying yours

I plan on keeping the mkIV for a good few years tbh, I'd rather splash on glass now i have the opportunity. For what i shoot, the af is more than adequate and i don't expect any problems with getting the images im after with my current body. Last weekend threw up eight (8) out of focus pics from nearly 600 so I'm not far away with set up

Pigpen101 wrote in post #18755688
I understand completely. Little out of my reach also. I've never even owned a car costing that much. If I bought that lens, I'd be sleeping with it because my wife would leave me.

BADADUMP! Pshhhhhhhh............

What can I say? I know the 300/200 combo made more sense yada yada yada...buts its the 400L guys.
I know, let's just say I'm weak

If you were really weak you'd need help to lift that.

I do CB It's a beast, definitely need to work on swinging this thing around. Just arrived on the Isle of Mull couple hours ago, to find an eagle on his usual perch. Could almost hear him laughing as I flailed around trying to get a lock on him when he took off straight over my head

Is it a V1 L IS? 5.4kg, yeah, that's a beast.