Canon RF 400mm f2.8 vs RF 600mm f4

Hey all,

I tried searching to see if anyone had covered this topic in the forums but hadn't seen anything on this specific topic.

I'm a longtime photography enthusiast beginning to start my side business, and I'm wondering from anyone out there who's used either of these lenses, which is better for sports/wildlife overall: the Canon RF 400mm f/2.8 or the RF 600mm f/4?

With the f2.8, you could obviously put a 1.4x TC on it to turn it into a 560mm f4 to get similar reach with the same max aperture as the 600mm, but I'm not entirely sure if you'll maintain the same sharpness and quickness of the autofocus with the TC attached.

Any thoughts?

For wildlife it really depends on what and where you're shooting.  If you are shooting larger mammals that you are able to get closer to like in Africa or bears in Alaska a 400 2.8 maybe more useful.  I was in Botswana last year and took my 600 but I wish I had a 400 2.8 a few times because of the light.

When I bought my first 600 F4 I was looking at the 400 also but because I also shoot a lot of birds and smaller things like chipmunks the 600 made more sense especially when adding the TC's to fill the frame .

I photographed with a 400/2.8, and 1.4x, and 2x, for 15 years.  While it was extremely flexible, given my regular shooting situations, if I were to do it again I'd start with the 600/4.  I would take some time to evaluate with your current lenses and typical expected subjects how often a 600mm is too long, and a 400mm too short.

I currently shoot 300/2.8 and 800/5.6, both with teleconverters.  I want something affordable and handholdable in between, so likely the EF 500/4.5 L.  If I find an affordable used EF 600/4 I would likely take it instead.

400/2.8 + TC1.4x vs 600/4

As a retired professional i have one tip for you.  Before spending 12-13,000 dollars on one of these fine lenses, I hope you take the time to rent and evaluate each, on it's own merits.  Your specific shooting style, and a lot of other things will come into play, and you will need to live with your ultimate decision.  If you won't be shooting with it constantly, renting may be the way to go at first.  Anything above 300/2.8 was always borrowed from Canon.

They should both exhibit similar characteristics.

I'm in the market for an RF super tele, but neither one has wow'ed me in to a purchase. I was leaning more to the 400 as it is largely a little more versatile with the 2.8, but if you are after birds the 600 is the way to go. If you are mixed, mammals and birds, its a little more tricky.

But ultimately, you have to factor in the type of wildlife and your average location. For example, a Costa Rican birder would likely lean toward a 400 2.8 because they are shooting under a canopy of trees. But for a Californian birder, the 600 wins almost hands down.

Again, I'm waiting for something a little more compelling as I still have an EF 500L II to hold me over. But, to answer the question about performance, most people will not care about the difference in performance between the 400 and 1.4x and the 600, but the 600 is better IQ-wise. AF-wise didn't notice a difference with an R5, but that was a very short sample of the two.