A prime lens often shows less distortion than a zoom lens would at an equivalent focal length. Similarly, a zoom’s sharpness varies across its focal range, so depending on the focal length you use most, you might get greater image quality for your buck from a telephoto prime than a long zoom. Check your EXIF data—if you notice yourself shooting primarily at a given focal length, a prime lens at that length might be the one for you. Shoot across a range of focal lengths? Remember that a zoom lens isn’t a compositional tool. Make sure that when you shoot, you choose a focal length for its characteristics of compression and the ways its field of view helps you tell a story. If that’s how you use it, a zoom upgrade may be right for you.