Help needed picking new prime lens

[antonio993]

Hi all!

I shoot mainly aviation and a bit of wildlife with my R7 and my EF 100-400mm ii and RF 200-800mm. Both of these lenses are really sharp and produce great results.

Now I was thinking, can I improve on these already very sharp lenses by getting a prime lens? However I'm not rich so looking at the budget options only:

EF 400 400mm f/4 DO IS USM (first gen) / EF 400mm f/5.6 L USM

TL/DR: have you shot with these lenses and can you tell me how sharp they are and if there is a point "upgrading" to them in the first place

thanks!

[rs-eos]

While I exclusively use prime lenses, I don't think getting a dedicated 400mm prime in your case will provide much, if at all.

Recommend renting RF primes if you're really curious as to the results. Otherwise, save your money for lenses that would provide additional focal lengths than what you already have.

[ebiggs1]

I have used some of the big white primes (I own the 600mm f4L)  and I, too, agree with the Ricky, there is none to very little advantage and lots of disadvantages to using primes vs zooms. Once I got my Sigma 150-600mm f/5-6.3 DG OS HSM Sports Lens I don't  believe the 600mm prime has been out of its case. For years I begged Canon to make that lens. Well they finally did with the Canon RF 200-800mm f/6.3-9 IS USM Lens. You have the best lens already.