FE 100-400mm vs FE 70-200 f2.8 for planespotting

[FlatRockSnapper]

Hi there,

I’m a new planespotting enthusiast with an a7iii and some budget to invest in a good lens. I cannot find a definitive answer on whether to go for the 100-400 or the 70-200 f2.8 (possibly with a teleconverter). This is for commercial jet planes at airports mainly. 
 

Is my understanding correct that if I’m shooting around f8 to keep whole aircraft in focus the faster 70-200 doesn’t really help me, but that f8 on both these lenses will be about the same? 
 

Thanks!

[LiveShots]

If you are going to be hanging around f8, then maybe the 200-600mm would be a better option.

[Wally The Confused]

If you are working around f 8, then, you need to re define your choices !

Sony makes 2 great  70 - 200  lenses !

One, is the 2.8 and the other is  F 4 !

If you want to use it at  f 8, then, buying the   70 - 200  f 2.8  , is a collossal waste of money !

The Sony  70  -  200   F 4,  is less than half the price of the   70 - 200 2.8 !

As regards the new    200 - 600 ??

I would read a lot of careful independent reviews, before jumping on that bandwaggon !

Good Luck

[FlatRockSnapper]

Thanks!

[Pieter]

The 70-200 f/4 doesn't take teleconverters so if 200mm is not enough reach, I'd disregard that option.

[Alejandro Espeche]

I have the sony FE 100-400 and it is insanely good, I use it on the A7R3 for birds and airplanes in flight and sometimes also on the low end A6xxx where it works excellently.