If you want the absolute sharpest single lens that covers most bases for under $2k, dont bother with the super-zooms. That R5 sensor is honestly pretty unforgiving and youll notice the softness on anything that isnt high-quality glass. I highly recommend the Canon RF 24-105mm f/4 L IS USM. It is way more consistent across the frame than the 24-240mm options. It's built like a tank, weather-sealed for travel, and the optics are legit top-tier. You can usually find it for around $1,299. If you find you really need more reach later on, you've still got $700 left in your budget. You could even pick up a Canon RF 100-400mm f/5.6-8 IS USM for those rare times you need to zoom way in and still stay under your total limit. But for a one-lens-only setup, that 24-105mm L is the sweet spot for performance and real-world usage.

This ^

Totally agree with the point about calibration and real-world testing. I remember when I first got my R5, I was so obsessed with finding that perfect 'do-it-all' lens for a big trip. Honestly, I spent way too much time looking at charts and not enough time actually shooting. I ended up getting a versatile zoom that looked amazing in tests, but once I got it out in the field, I realized the field curvature was a total mess for landscapes. Basically, the center was sharp but the edges just fell off a cliff, which your not always going to see in a simple MTF chart. Well actually, I ended up almost returning it because I thought it was a bad copy, but after some side-by-side testing with a friend's gear, I realized it was just the trade-off for having that much range. It really changed how I look at benchmarks—they're a good guide, but they dont tell the whole story about how the lens handles flare or micro-contrast in the wild. I've learned to rent everything first now to see how it actually handles the 45MP sensor, right?

Been there! Unfortunately, my Canon RF 24-240mm f/4-6.3 IS USM, while versatile, wasn't as good as expected sharpness-wise on my R5. For travel, consider the Tamron 28-200mm f/2.8-5.6 Di III RXD. I had issues with corner sharpness on the Canon, which the Tamron seems to address based on user reports. Worth checking out!

Unfortunately, all-in-ones are never tack-sharp. The Canon RF 24-240mm f/4.5-6.3 IS USM is decent, but expect significant distortion at the wide end. Chromatic aberration is also present. Consider primes instead.

Tamron 28-200mm. Sharp enough, and leaves cash for travel! I got mine used for $700.

Sigma's your best bet. Check MTF charts; Tamron's QC can be iffy despite good reviews.

For travel, be careful: Tamron's 28-200mm is light, but *always* use a lens hood. Protect your investment.

Honestly? DIY lens calibration can be tricky on the R5. Had issues with sharpness after attempting it. Consider a Canon RF 24-105mm L IS USM and a professional calibration. Peace of mind, ya know?