It seems the 64MP telephoto camera is the one that will be used for recording 8K videos. That makes sense, as 8K videos have a resolution equivalent to 33.2 megapixels, so only the Galaxy S20 Ultra's primary rear camera will be able to shoot 8K videos. Furthermore, since the S20 and S20+ won't feature the periscope zoom lens that we will find on the S20 Ultra, the two phones will apparently capture 64MP photos and then crop each image depending on what zoom level has been selected by the user.
However, it does make us wonder if the telephoto camera on the Galaxy S20 and S20+ will also have a longer focal length or if it will depend purely on pixel/image cropping of a 64MP photo for zooming in on subjects. Without a longer focal length compared to the main camera, any form of zoom is simply digital zoom, and that would be a step back from the zooming capabilities of previous Galaxy flagships.
Thankfully, we're merely two weeks away from the official unveiling of the Galaxy S20 series, so we will be getting answers on exactly how the cameras will work on the three models very soon. At this time, the only thing we know for sure is that the Galaxy S20 Ultra is the model you would want to pick up if you want the best camera experience, among other things.
