which lens should I buy for portraits on my Canon EOS R7? sorry if this is a super basic question but I honestly have no clue what I am doing and I have a friends wedding coming up in like three weeks so I need to figure this out fast. someone told me to get a prime lens because they make the background all blurry and pretty but I dont even know what that means really. I have like 400 dollars to spend maybe 450 if I push it. I saw a 50mm one online and a 35mm one but I dont know which one fits the R7 or if it even matters. please help I am kind of panicking lol...