A 35mm lens with a wide maximum aperture is a classic choice for a wide range of applications. With a wide but still mostly neutral focal length and lots of light-gathering and subject-isolating power, it is equally at home in the studio, at a wedding, or on the street. For Sony shooters, the top option is the FE 35mm f/1.4 GM, and this excellent video review takes a long-term look at the lens and how its price, performance, and image quality stand up to other options.
Street photography is not the easiest genre to get into, especially if you tend to have a more timid personality or enjoy working alone. However, it can be a tremendously interesting one, and even if it is not your primary pursuit, it can do a lot of good to sharpen your skills in many other genres. If you are interesting in street photography and wondering how to get started, check out this fantastic video tutorial that will show you everything from composition and lighting to gear choices and editing.
