p.1 #1 · EF 400mm 2.8 IS II autofocus performance?
Is it true that this lens takes 1.9 seconds to sweep between mfd and infinity?
I'm photographing athletes running indoor (ISO 6400) 60m sprints (6.6s) and 60m hurdles (7.8s) approaching head-on (no lateral movement in frame). When the subject is ~40 meters away, does this lens keep critical focus on the eyes specifically for that one specific frame at the peak of the hurdle just as the head snaps forward? (That's the only frame that matters, so if it misses that one critical frame then it may as well have missed them all, I don't care if it comes back in focus one or two frames later.)
Also, "usable" with softness/back-focus on the eyes is not good enough; critical focus strictly means critical focus.
Body is R5 II, will set AF case M, -2 sens, +2 accel/decel.
There is no rental available for this lens, before anyone parrots that.
The reason I ask about this lens specifically then is that this is the decision point: if the EF 400 IS III or RF 400 are necessary then the money calculation shifts heavily against the Canon system.
p.1 #2 · EF 400mm 2.8 IS II autofocus performance?
I don't believe there is a single 'time limit' before the lens goes from mfd to infinity, but rather is dependent on the camera being used and the available lighting.
Jim
p.1 #3 · EF 400mm 2.8 IS II autofocus performance?
That's a pretty specific requirement that will also be camera-dependent.
Can you arrange to borrow a copy of that lens to evaluate it for your use case? If you are considering a particular used one, is there a way to arrange a trial period with the seller?
Edit: some older EF lenses impose framerate limitations when used with R bodies. The good news is that this lens is on the compatible list:
p.1 #6 · EF 400mm 2.8 IS II autofocus performance?
I am still using the EF 400mm 2.8 IS II and have used it with R3 and R5 bodies previously and currently using it with R1's and R5 Mark II's. The lens should have no problem sticking with your subjects assuming you have all your AF settings set up for that type of use and the lens is in good working order.
Dec 19, 2025 at 12:30 AM
AmbientMike Offline • • • • • • [X]
p.1 #7 · EF 400mm 2.8 IS II autofocus performance?
Can't tell you, but the af probably isn't going to have to move much at 20m+, assuming you start with focus closer to infinity.
Curious about Canon costing more, thinking latest greatest super teles are about the same price regardless of the manufacturer
p.1 #8 · EF 400mm 2.8 IS II autofocus performance?
AmbientMike wrote:
Curious about Canon costing more, thinking latest greatest super teles are about the same price regardless of the manufacturer
Used prices (canada):
EF 400 IS II under $6000
EF 400 IS III $11000
RF 400 $12000
FE 400 $9000
p.1 #9 · EF 400mm 2.8 IS II autofocus performance?
gromacs wrote:
Used prices (canada):
EF 400 IS II under $6000
EF 400 IS III $11000
RF 400 $12000
FE 400 $9000
Rest of the kit is blow for blow
I believe AmbientMike is saying that a new 400 2.8 from Canon, Nikon and Sony are all about the same price.
B&H:
Canon RF 400mm f/2.8 L IS USM Lens: $13,399
Sony FE 400mm f/2.8 GM OSS Lens: $12,999
Nikon NIKKOR Z 400mm f/2.8 TC VR S Lens: $14,696.95 (with a $2000 discount for a sale price of $12,696.95)
Dec 19, 2025 at 03:59 PM
AmbientMike Offline • • • • • • [X]
p.1 #10 · EF 400mm 2.8 IS II autofocus performance?
Caleb Williams wrote:
I believe AmbientMike is saying that a new 400 2.8 from Canon, Nikon and Sony are all about the same price.
B&H:
Canon RF 400mm f/2.8 L IS USM Lens: $13,399
Sony FE 400mm f/2.8 GM OSS Lens: $12,999
Nikon NIKKOR Z 400mm f/2.8 TC VR S Lens: $14,696.95 (with a $2000 discount for a sale price of $12,696.95)
p.1 #12 · EF 400mm 2.8 IS II autofocus performance?
gromacs wrote:
Is it true that this lens takes 1.9 seconds to sweep between mfd and infinity?
I forgot to post last week, but I tested this from infinity to MFD and it did take around two seconds in low light conditions with a 1DX Mk II. I meant to test in daylight outdoor, but forgot.
p.1 #13 · EF 400mm 2.8 IS II autofocus performance?
Caleb Williams wrote:
I forgot to post last week, but I tested this from infinity to MFD and it did take around two seconds in low light conditions with a 1DX Mk II. I meant to test in daylight outdoor, but forgot.
If you consider how a 400 is used, I can’t think of any scenario where a subject would be moving from infinity to mfd in anywhere close to 2 seconds (and if it is, it’d be moving pretty fast and I would suggest getting out of the way!)
I’ve never run into issues where the lens couldn’t keep up with any subject.
I considered upgrading from the EF 400mm II to the III or RF, but other than the significant weight reduction, I didn’t see any other real-world improvements to focusing speed or image quality that were substantial enough that it was worth the cost to upgrade.
I’m not hiking with the 400, so the weight of the lens doesn’t really bother me.
p.1 #14 · EF 400mm 2.8 IS II autofocus performance?
fgphoto wrote:
If you consider how a 400 is used, I can’t think of any scenario where a subject would be moving from infinity to mfd in anywhere close to 2 seconds (and if it is, it’d be moving pretty fast and I would suggest getting out of the way!)
I’ve never run into issues where the lens couldn’t keep up with any subject.
I was also wondering about that scenario and then only thing I can think of would be some type of racing where you need to move from a closer subject to one in the background quickly. But that's not normally MFD back to infinity.
p.1 #15 · EF 400mm 2.8 IS II autofocus performance?
OP here. I've tested it myself (first hand experience). The sweep during hunting on 400mm 2.8 is deliberately slow, and utterly unrepresentative of the max speed the AF motor(s) can sustain. Max speed can be achieved by using focus preset/recall, or by giving it a distinct subject. At max speed, it takes about 0.4s from mfd to inf.
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