Worth upgrading from 100-400mm to EF 400mm f/2.8 L IS II USM?

[Ravanelli]

So I have just upgraded from a 5div to a stunning 1DXiii...........

Long story short, I have been using a 100-400 L IS ii for the last year. I shoot exclusively military aviation, fast jets etc. I spend a great deal of time at the Mach Loop in Wales, UK. This is a military low flying area. The 100-400 has been good, mated to the 5div. 

The opportunity has come about to buy a lens I have wanted for quite some time, and I think it would be great with the 1DX3. It is an EF 400mm 2.8 L IS ii. 

Like most seem to think, it's a significant leap in £££ / $$$ to buy this lens (over here in the UK in December 2025 an absolute mint one would be around £5000). I am aware of the weight penalty, and will have a new monopod for when I thinks I will need it.

So is it really worth the upgrade?

If anyone uses this kind of set up handheld I would welcome your thoughts. I'm physically strong and have weight trained all my life, so ok with heavier items.

Thanks,

Rav

[Ravanelli]

Thank you Marc

[SignifDigits]

Seconding Marc's suggestion for posting.  I think my favorite is the F-14 vapour, but I'm partial to vapour shots.  Quite a community shooting there with you it seems.  I'm sure you will draw some attention with your big Cannon glass - hopefully positive supportive attention and not the other kind.

[Ravanelli]

The Mach Loop (Wales, UK, military low flying area) is an awesome way to spend my time. I have visited 6 times this year. I’m retired now. The weather (and thus the light) can be poor, so that’s one of the reasons for wanting a 400 2.8. The other is getting the chance to increase the bokeh with the wider aperture. 

[Ravanelli]

It's all rather fun. Lots of different abilities and gear. Plenty arrive just with a cellphone. The aircraft are low and noisy. Always a good laugh. Plenty of rookies turn up, and there is plenty of advice for them regarding camera settings etc. Lunch is taken as you are away from any kind of facility. Its great fun.

[wq9nsc]

I love my EF 400 f2.8 IS II!  I shoot primarily sports where the wider aperture is important but what I think you will notice most about this lens is how quickly it grabs focus.  In general, a prime lens is less complex than a zoom lens and that shows up in focus speed.  And it produces amazingly sharp images.

You won't regret buying it and I use mine handheld for shooting soccer and U.S. football.  It balances beautifully on the 1DX III body.

Rodger