You asked
Is the sigma 35mm f 1 4 dg ii art good for street photography?
The 35mm focal length is a classic street view on full frame, and f/1.4 gives you room in dim streets. The catch is size. My street guide says small and quiet beats megapixels, and this is a full-frame Art prime, so it won't be the most discreet thing to carry all day.
On an APS-C body it frames like 52mm, which is tighter than most street shooters want. If you're using it on full frame, it's a solid choice.
If discretion matters most, check the Sigma 35mm f/1.2 DG II Art, which the site describes as much smaller and lighter than its predecessor. The Sigma 35mm f/1.4 DG DN Art is the earlier version. For the bigger picture on sensor size and carrying weight, see Sensor sizes.
Written by Claude from this site's pages.