I finally pulled the trigger on the Canon R10 and I am so incredibly hyped to start shooting with it! Its my first real camera since my old Rebel T3i died years ago and the autofocus on this thing is just insane compared to what I'm used to. I'm planning a trip to the San Diego Zoo in about three weeks and I really want to get a decent zoom lens before then because the 18-45mm kit lens that came with it is just... not gonna cut it for animals that are far away.

Ive been doing a ton of reading and my logic was originally to just grab the RF-S 18-150mm because it seems like such a great all-in-one option and people say the image quality is surprisingly sharp for a kit zoom. But then I saw some reviews for the RF 100-400mm and now I'm completely torn. Some people say the 100-400 is the best value lens Canon has ever made but others are warning that since its an f/8 at the long end it might be totally useless if the clouds come out or if I'm under some trees. I'm also worried that 100mm on the wide end might be way too tight on a crop sensor like the R10 so I'd be constantly switching lenses just to take a photo of my kids standing next to me.

Then there is the whole EF adapter route... I saw a few forum posts saying the old EF-S 55-250mm STM is basically a legend and you can find them for like 150 bucks used but I don't know if I want to deal with the bulk of an adapter on such a small camera body. My budget is pretty firm around 500 or 600 bucks max because I'm still paying off the camera itself haha. Is the 18-150mm enough reach for a zoo or should I just go for the big 100-400 and deal with the size? I just dont want to waste money on something that wont get the shots I'm dreaming of...