I saw this today and felt your pain. I bought the Canon RF 24-105mm f4L IS USM for a trip last year and unfortunately found it pretty disappointing for evening street photography. The f4 just isnt as good as expected when the sun goes down, even with the R5 sensor. I had issues with noise and grain that just ruined some shots I really cared about.

• The Canon RF 24-70mm f2.8L IS USM is basically the gold standard and hits right at your $2399 budget.
• You lose that extra reach, which kinda sucks for architectural details, but the low light performance is a massive jump.
• If you do go the f4 route to save money, definitely pack a tiny Canon RF 50mm f1.8 STM for those night walks in Italy. Its a tough trade-off but dont settle for f4 if you're already worried about it... youll just be frustrated the whole time. Just shout if you need more technical specs on the low light stuff!

I went through this exact same struggle before a trip to Rome a few years back. Choosing the Canon RF 24-105mm f/4L IS USM ended up being the right move and I didnt regret it for a second.

• extra reach for tight architectural details
• much lighter for those long walking days
• leaves about $1100 in your pocket for a fast prime like the Canon RF 50mm f/1.8 STM The R5 sensor handles high ISO like a champ, so shooting at f/4 at night isnt the disaster people claim. If youre really worried about the dark, just rely on that IBIS. Its incredible and works well for long exposures. The Canon RF 24-70mm f/2.8L IS USM is a beast, but for travel, that 105mm reach is king. Tbh, spending your entire $2400 budget on one heavy lens might make you less likely to carry it everywhere.

Regarding what #2 said about "I saw this today and felt your pain...."

• I think there's a middle ground. Honestly I've been super satisfied with the Canon RF 24-105mm f4L IS USM for travel. Just grab that and a Canon RF 50mm f1.8 STM for night stuff. It works well and keeps you way under budget... basically the ultimate kit for Italy without blowing the full $2400.

Adding my two cents here because I am right there with you!

• So the consensus here is basically choosing between the extra reach of the Canon RF 24-105mm f4L IS USM or the low light speed of the Canon RF 24-70mm f2.8L IS USM but honestly its just ridiculous that gear is this expensive!
• It drives me crazy that $2400 is considered a budget for one lens and you still have to worry about whether it will actually perform when you need it. Like why are we paying car prices for glass these days? Its so stressful tho!
• These companies are basically just squeezing us for every cent now and its such a scam that you have to stress this much about reliability on a trip you should be enjoying... it makes me so mad!
• Love the R5 but the cost of lenses is just insane and it feels like the barrier to entry for good photography is getting higher every year for no reason. Its so frustrating trying to find something you can actually trust without going broke! I am totally here for you if you need to rant more about it because this stuff is just exhausting!