For most of us who started with the kit lens that came with the camera, it didn't take long to become envious of the vast array of lenses available. But which lens should I buy? "All of them. I want all the lenses." Yes, we've all been there, unfortunately, cost generally an impeding factor. So what to do what to do?
As quick as you got lens envy, you also probably got sticker shock. Lenses aren't cheap and a good lens can range from hundreds to thousands depending on the specs. Yes, the shots on that lens are magnificent, but unfortunately, it may take time to get a shot similar to the one you saw and won't pay off right away necessarily. So what lenses should I buy and which should I rent? That's going to vary based on three major factors.
Cost: No surprisingly what you can afford comes first. If you can't afford it, don't buy it! Don't bank on future projects, it really sucks when you're looking at your lens and wishing it was cash for your car payment. Cash flow is king and renting what you need for specific projects keeps your risk low and more cash in your pocket.
Usage: That fisheye lens is awesome yes, but how often are you going to use it? Specialty lenses ad that extra level of unique production value but they often end up sitting in your bag far more than your other lenses simply. And it's not like there's one specialty lens to rule them all, they all have their own specific purpose. So when a project comes along that you need a macro? Rent. If all you do is take pictures of bugs? Buy.
Preference: Seems simple but take advice on which lens to buy with a grain of salt. Try it for yourself, before you buy, rent. It'll save you a lot of headaches down the road. What works for someone shooting documentaries may not be suited to your needs as a wedding photographer or videographer.