answer: as the STM lenses have almost completely silent autofocus
paragraph_question: question: How is the quality of the autofocus?, context: I bought this lens mostly for video, as the STM lenses have almost completely silent autofocus, which helps tremendously when shooting video with the internal mic, or a camera-mounted mic. The kit Lens that came with my camera is completely silent, and I have yet to hear any camera noise picked up hen shooting video, even in quiet, indoor shoots. I bought this lens for the same purpose, as well as shooting photos, as it is a great focal length for video, and the low aperture is great for low-light photos. Here are my conclusions:For Photos: This lens is incredible. The pictures are razor sharp, and when you shoot with the aperture wide open, the bokeh effect you can achieve is really cool and makes for some beautiful, intriguing photos. The autofocus is quick and responsive, allowing you to quickly frame and shoot. The only downside to this lens is since there is no Image Stabilization, you have to be very steady when shooting hand-held, especially if you get below 1/100th shutter. Adjusting the settings, you can usually find a clear shot, it just may take some toying. On a tripod, you have nothing to worry about, obviously. This was definitely a good purchase for photos.For Videos: The quality of video produced by this lens is great. It lets in some serious light with the f/2.8 aperture, so you can do some good low-light shoots. The focal length is ideal for most video applications, but the lack of zoom does make for some walking around to frame the shot properly. The downside with this lens when compared to the STM 18-55mm is that the autofocus motor makes some noise. I was used to complete silence with STM lenses, and this one, although quiet, can still be picked up, especially when shooting with the internal mic. It's nothing compared to a non-stm lens, which are much louder, but it is audible and can be picked up in quiet shoots. Not a huge deal, but it is worth noting, if this lens is being purchased with that function in mind. If you are using any kind of external micing, you should be fine.Pros:Crisp, good color, fast autofocus, solid construction, light-weight, small form factorCons:Autofocus a little noisy 
question: How is the quality of the autofocus?
sentence: I bought this lens mostly for video, as the STM lenses have almost completely silent autofocus , which helps tremendously when shooting video with the internal mic, or a camera-mounted mic.
paragraph: I bought this lens mostly for video, as the STM lenses have almost completely silent autofocus, which helps tremendously when shooting video with the internal mic, or a camera-mounted mic. The kit Lens that came with my camera is completely silent, and I have yet to hear any camera noise picked up hen shooting video, even in quiet, indoor shoots. I bought this lens for the same purpose, as well as shooting photos, as it is a great focal length for video, and the low aperture is great for low-light photos. Here are my conclusions:For Photos: This lens is incredible. The pictures are razor sharp, and when you shoot with the aperture wide open, the bokeh effect you can achieve is really cool and makes for some beautiful, intriguing photos. The autofocus is quick and responsive, allowing you to quickly frame and shoot. The only downside to this lens is since there is no Image Stabilization, you have to be very steady when shooting hand-held, especially if you get below 1/100th shutter. Adjusting the settings, you can usually find a clear shot, it just may take some toying. On a tripod, you have nothing to worry about, obviously. This was definitely a good purchase for photos.For Videos: The quality of video produced by this lens is great. It lets in some serious light with the f/2.8 aperture, so you can do some good low-light shoots. The focal length is ideal for most video applications, but the lack of zoom does make for some walking around to frame the shot properly. The downside with this lens when compared to the STM 18-55mm is that the autofocus motor makes some noise. I was used to complete silence with STM lenses, and this one, although quiet, can still be picked up, especially when shooting with the internal mic. It's nothing compared to a non-stm lens, which are much louder, but it is audible and can be picked up in quiet shoots. Not a huge deal, but it is worth noting, if this lens is being purchased with that function in mind. If you are using any kind of external micing, you should be fine.Pros:Crisp, good color, fast autofocus, solid construction, light-weight, small form factorCons:Autofocus a little noisy 
sentence_answer: I bought this lens mostly for video, <hl> as the STM lenses have almost completely silent autofocus <hl> , which helps tremendously when shooting video with the internal mic, or a camera-mounted mic.
paragraph_answer: I bought this lens mostly for video, <hl> as the STM lenses have almost completely silent autofocus <hl>, which helps tremendously when shooting video with the internal mic, or a camera-mounted mic. The kit Lens that came with my camera is completely silent, and I have yet to hear any camera noise picked up hen shooting video, even in quiet, indoor shoots. I bought this lens for the same purpose, as well as shooting photos, as it is a great focal length for video, and the low aperture is great for low-light photos. Here are my conclusions:For Photos: This lens is incredible. The pictures are razor sharp, and when you shoot with the aperture wide open, the bokeh effect you can achieve is really cool and makes for some beautiful, intriguing photos. The autofocus is quick and responsive, allowing you to quickly frame and shoot. The only downside to this lens is since there is no Image Stabilization, you have to be very steady when shooting hand-held, especially if you get below 1/100th shutter. Adjusting the settings, you can usually find a clear shot, it just may take some toying. On a tripod, you have nothing to worry about, obviously. This was definitely a good purchase for photos.For Videos: The quality of video produced by this lens is great. It lets in some serious light with the f/2.8 aperture, so you can do some good low-light shoots. The focal length is ideal for most video applications, but the lack of zoom does make for some walking around to frame the shot properly. The downside with this lens when compared to the STM 18-55mm is that the autofocus motor makes some noise. I was used to complete silence with STM lenses, and this one, although quiet, can still be picked up, especially when shooting with the internal mic. It's nothing compared to a non-stm lens, which are much louder, but it is audible and can be picked up in quiet shoots. Not a huge deal, but it is worth noting, if this lens is being purchased with that function in mind. If you are using any kind of external micing, you should be fine.Pros:Crisp, good color, fast autofocus, solid construction, light-weight, small form factorCons:Autofocus a little noisy 
paragraph_sentence: <hl> I bought this lens mostly for video, as the STM lenses have almost completely silent autofocus , which helps tremendously when shooting video with the internal mic, or a camera-mounted mic. <hl> The kit Lens that came with my camera is completely silent, and I have yet to hear any camera noise picked up hen shooting video, even in quiet, indoor shoots. I bought this lens for the same purpose, as well as shooting photos, as it is a great focal length for video, and the low aperture is great for low-light photos. Here are my conclusions:For Photos: This lens is incredible. The pictures are razor sharp, and when you shoot with the aperture wide open, the bokeh effect you can achieve is really cool and makes for some beautiful, intriguing photos. The autofocus is quick and responsive, allowing you to quickly frame and shoot. The only downside to this lens is since there is no Image Stabilization, you have to be very steady when shooting hand-held, especially if you get below 1/100th shutter. Adjusting the settings, you can usually find a clear shot, it just may take some toying. On a tripod, you have nothing to worry about, obviously. This was definitely a good purchase for photos. For Videos: The quality of video produced by this lens is great. It lets in some serious light with the f/2.8 aperture, so you can do some good low-light shoots. The focal length is ideal for most video applications, but the lack of zoom does make for some walking around to frame the shot properly. The downside with this lens when compared to the STM 18-55mm is that the autofocus motor makes some noise. I was used to complete silence with STM lenses, and this one, although quiet, can still be picked up, especially when shooting with the internal mic. It's nothing compared to a non-stm lens, which are much louder, but it is audible and can be picked up in quiet shoots. Not a huge deal, but it is worth noting, if this lens is being purchased with that function in mind. If you are using any kind of external micing, you should be fine. Pros:Crisp, good color, fast autofocus, solid construction, light-weight, small form factorCons:Autofocus a little noisy