Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Inexpensive fast prime, but buy a hood!

This lens is quite fast. It captures pictures in low light wonderfully on my crop camera. I'm sure the performance would be even better with full frame. This is the only lens I use if I know I'm going to be indoors at some point. I'm not a pixel peeper, but the picture quality is great. I am sure other reviewers with far better training than I have provided adequate descriptions of the picture quality.At any rate, the focus mechanism looks to be quite delicate. The barrel extends from the front of the lens when focusing. This lens is known to have some problems with backfocus or soft focus that I would guess are a product of the barrel being knocked when extended. I wouldn't carry this lens without a hood. I bought an inexpensive third party hood from Amazon and it works great.