Saw this earlier but just now responding. Like someone mentioned, native glass is key for that Dual Pixel AF. I would suggest being cautious about the weight if youre traveling a lot tho. I actually went with the Canon RF 24-105mm f/4L IS USM because the sharpness holds up better than my old EF stuff. Just make sure f/4 is enough for those evening games... it definitely saves you some serious cash tho.

Regarding what #1 said about "Basically had the same issue when I moved..."

• I felt that 100%. I was so satisfied once I swapped to native glass. I spent ages looking at the MTF data for that sensor.
• Canon RF 24-70mm f/2.8L IS USM: Nano USM motors are lightning fast for kids soccer. Works well for that sensor.
• Canon RF 24-105mm f/4L IS USM: Better travel weight but loses a stop of light. I honestly love the 24-70, it works perfectly.

Basically had the same issue when I moved from my 5D IV to mirrorless. That adapter is great for saving cash but it adds like an extra inch of leverage that just ruins the center of gravity during long days. Was at a shoot in Michigan last year and the hunting on my old glass was driving me insane... almost missed the best shots because the motor just couldnt keep up with the eye-tracking tech. You might want to consider these depending on how much reach you need:

• Canon RF 24-70mm f/2.8L IS USM
• This is the gold standard. The Nano USM motors are basically silent and way faster than the old EF glass.
• Canon RF 24-105mm f/4L IS USM
• Be careful though, the f/4 aperture might struggle if the sun starts going down during those soccer games. Make sure to prioritize the f/2.8 if you can. It handles those 45 megapixels without getting soft at the edges, plus it stays under your $2600 cap.

Just catching up on this thread today. ^ This. Also, summarizing what everyone has said so far: native glass is basically mandatory to fix that autofocus hunting, and it really comes down to the f/2.8 weight vs f/4 convenience. Before you spend your cash, I would suggest looking at the brand ecosystem differences. Unlike Sony where you can grab a cheaper Sigma 24-70mm f/2.8 DG DN Art II, Canon keeps their full-frame RF mount closed to third-party autofocus. So we are stuck paying the Canon premium. If you are deciding, make sure to watch out for these details:

• Be careful with adapting older third-party glass like the Tamron SP 24-70mm f/2.8 Di VC USD G2. It might save money, but the autofocus communication issues on the R5 II will drive you crazy just like your EF lens does.
• You might want to consider the Canon RF 24-105mm f/4L IS USM if weight is your main priority, but be warned that you will struggle during night games or indoor sports.
• If you need that f/2.8, the Canon RF 24-70mm f/2.8L IS USM is the safest bet, but make sure to test the weight in a store first because it is a heavy beast for casual daily carry.

^ This. Also, totally get the frustration with the legacy glass. I spent way too many weekends battling focus lag before finally switching to my current setup. It was like night and day once the communication protocol matched the sensor speed. Honestly, the biggest thing I learned wasn't even the glass itself but how the internal aperture control behaves during high-speed bursts. When I moved away from the adapters, I noticed my hit rate on tracking moving subjects shot through the roof because the camera wasn't waiting on mechanical conversion lag. It feels way more balanced in the hand now, especially when tracking kids running around. Just keep in mind that the lens correction profiles and digital stabilization are doing heavy lifting in the background on these newer bodies. Once I stopped fighting the gear and synced the software settings with the new mount, everything just clicked into place. Dealing with that extra physical length on the adapter was annoying, but the data bottleneck is what really held me back for so long.

TL;DR: The Canon RF 24-70mm f/2.8L IS USM is the most reliable all-purpose choice for the R5II tracking and resolution within your budget. To add to the point above: native glass is really the only way to ensure the Coordinated Image Stabilization works at its peak. When you use the adapter with older EF glass, the communication speed between the lens and body often becomes the bottleneck for the Dual Pixel AF system. The Canon RF 24-70mm f/2.8L IS USM provides a consistent f/2.8 aperture which is basically a necessity for maintaining high shutter speeds during evening soccer matches without pushing the ISO into noisy territory. Quick tips for reliability:

• Update lens firmware via the camera menu to optimize AF performance for the Mark II sensor.
• Map the lens control ring to ISO to adjust for changing light instantly without taking your eye off the EVF. Honestly, the 24-70 handles the 45MP sensor with much better edge-to-edge clarity than the f/4 version. Tbh its a heavy investment but worth it for the peace of mind.

To add to the point above: ignore the zoom range debate for a second and think about what you actually shoot most. If soccer is a priority, you need that extra stop of light, but if you want to travel light, you gotta make a compromise. I have been using the Canon RF 24-70mm f/2.8L IS USM for a while now and honestly, it is the only way to get those sharp shots of kids running around the field. Check out these two paths before you buy:

• Canon RF 24-70mm f/2.8L IS USM: Heavy, but the focus tracking is flawless and it is perfect for indoor or evening sports.
• Canon RF 24-105mm f/4L IS USM: Much easier to carry all day, but be careful at night games because your ISO will jump fast. I would suggest sticking with the 24-70 if you can handle the weight. Having used both, the f/2.8 glass just handles the R5 II sensor better in low light. Just dont go for any third-party adapters at this point, they really just slow you down.