topic Re: RF 400mm f/2.8 Lens Tips: Autofocus is slow in EF & RF Lenses

RF 400mm f/2.8 Lens Tips: Autofocus is slow

Zhaopian — Thu, 16 Oct 2025 18:28:33 GMT

Hello,

I use the RF 400mm f/2.8 lens with either my R1 or R3 to shoot football and soccer.

I have a lot of difficulty getting the lens or camera to focus fast. It's not that I don't get good shots with it, but I seem to get a disproportionate number of out-of-focus shots compared to my 70-200mm lens with either camera body. Or I just can't get it to focus fast enough to get a shot.

I bought the lens and my R1 used from mpb.com, but I suppose there is still a minute chance the is an anomaly with the gear. Despite this, I do think the speed of the autofocus is as it should be when I use the 70-200mm or 24-70mm, so I tend to think I can rule out a problem in either of those camera bodies.

So, unless the 400mm lens has a problem that needs professional repair, what should I be doing to get more in-focus shots? I've tried using the pre-focus ring, but once fast action starts happening, it seems to be useless. There is just too many times relative to the other lenses where I miss the shot because I can't get the lens to focus fast enough when shooting sports.

Thank you.

Re: RF 400mm f/2.8 Lens Tips: Autofocus is slow

wq9nsc — Thu, 16 Oct 2025 20:28:29 GMT

I have been using 1 series DSLR bodies (currently 1DX III) with the EF version of the 400 f2.8 lens for several years and the lens acquires focus VERY quickly. I have tried R1 bodies a couple of times but have not been motivated to switch yet so I don't have a lot of familiarity with them.

With the 1DX III, I leave the camera AF set for focus priority instead of shot priority because I see no use in having an out of focus image but I have not found that to be a hindrance in capturing rapidly changing action.

Are most of your O-O-F shots occurring when rapidly switching between two places on a field (i.e. the QB release of a bullet followed by the reception 30 yards from the QB)? If so, what you may be running into is the slight amount of additional time it takes for the photographer to follow/frame the action using a longer focal length lens and the "cure" is to force yourself to immediately switch your view to the receiver the moment the ball leaves the QB's hand.

If the O-O-F shots are occurring in a sequence where you are following the same action (i.e. football running back or a soccer player working the ball through the box in soccer to get a shot) then you may want to consider how you are using/defining the AF area. When I first got my 1DX III bodies, it was interesting to watch it identifying "targets" using its full focus sensor area however I quickly found that limiting to a few potential points either dead center or lower center of frame (depends upon sport) works better for me. The various "cases" Canon has available to provide different AF personalities are excellent but you and the camera are still a system assisting each other and although the technology Canon has put into its AF system is incredible it still works better as the photographer's very capable partner. For me, it also keeps me mentally focused on the action keeping the key part of the play properly in frame using that smaller set of AF points.

At times, you will want to make strategic use of the AF stop buttons located in a circle around the lens. For example when shooting corner kicks in soccer, I focus on the keeps position and press one of the AF stop buttons and then follow the play through the camera even though the image isn't in perfect focus. Using this strategy, I have the lens pre-focused on where the action is most likely to happen and I can then let it snap to perfect focus instantly when the action starts near the prior selected point. I shoot with two bodies and for that reason I do not like having AF on a separate button, any additional finger placement creates another delay when you are switching bodies during a fast moving play BUT I do program the AF button on the camera body as an AF STOP button for the rare occasion when I want to have AF stop with a lens that doesn't have the AF stop buttons. With the big white primes, those buttons are perfectly placed when using both hands to manage the camera system.

Rodger

Re: RF 400mm f/2.8 Lens Tips: Autofocus is slow

ebiggs1 — Fri, 17 Oct 2025 14:23:28 GMT

I have not used the Rf 400 f2.8 either nor have I used a R1 but I have used a 1 Series and the ef 300mm f2.8 and it, too, focus very quickly (of course "quickly" is a subjective word). So, I would send your lens in and have a C&C done on it more for piece of mind than anything else. Let's make sure the lens is A-OK before we jump through hoops with technic and settings after all you said it was used. And you said your 70-200 was getting all you expect. Let's get it checked out. Call Canon 1 (800) 652-2666

Re: RF 400mm f/2.8 Lens Tips: Autofocus is slow

Waddizzle — Sat, 18 Oct 2025 09:08:03 GMT

Are you using Pre-focus AF?

Electronic shutter?

Highest frame rate (s)?

I don’t believe that the lens is capable of keeping up with the highest frame rates. I believe it was released in the 1990s.

Re: RF 400mm f/2.8 Lens Tips: Autofocus is slow

Anonymous — Sat, 18 Oct 2025 09:07:23 GMT

I use a RF400 2.8 on R1 and R5II, not for sport but BIF.

I find setting the focus limiter from 7m to infinity really makes a difference, set to full it sometimes takes to long, probably to much OOF/no contrast so the AF system has nothing to work with.

Re: RF 400mm f/2.8 Lens Tips: Autofocus is slow

Zhaopian — Sat, 18 Oct 2025 18:22:55 GMT

Electronic shutter, highest frame rate/high speed burst, and pre-capture (requires electronic shutter, I think). Not sure what pre-focus AF is.

On servo, AF case is set to Auto.

Re: RF 400mm f/2.8 Lens Tips: Autofocus is slow

Anonymous — Mon, 20 Oct 2025 13:38:53 GMT

Not sure what pre-focus AF is.

Either pre-continuous shooting or continous AF(I don't think R1 has this) but I'm not sure which he means.

Re: RF 400mm f/2.8 Lens Tips: Autofocus is slow

Zhaopian — Mon, 20 Oct 2025 14:18:00 GMT

Definitely happens with the former: switching between quarterback and receiver. Probably only happens with the latter if someone runs into the frame.

Re: RF 400mm f/2.8 Lens Tips: Autofocus is slow

Zhaopian — Mon, 20 Oct 2025 14:20:26 GMT

Actually, I've read or heard on Youtube that those features may actually be a problem and may drain the battery faster. I turned mine off some time ago, but will try it again just to see what happens.