I have a USB fisheye camera connected to a Windows 10 device and the camera has 7 possible frame sizes. When I preview each of them in Wondershare Filmora, I can see that the smaller ones tend to be zoomed in relative to the larger ones, like it's cutting off the edges. This makes sense because the largest resolution (1920x1080) shows a circular black border like it can see the sides of the camera. However, the smallest resolution (320x240) sometimes shows the black circle and sometimes it doesn't, meaning sometimes it's more zoomed in than other times. I've tested this by making actual recordings with both settings so I know it's not just a glitch in the preview window.
I've found that the smallest resolution's cropping depends on which resolution was selected immediately before. If I switch to 320x240 directly from one of the three tallest frame sizes then there's no cropping and I can see the black circle, but if I switch to it from one of the shorter sizes then it's zoomed in and I can't. The three tallest sizes don't all have the same aspect ratio, but they are the only three resolutions that are associated with 30 frames per second. The other resolutions are all 60 or 120.
So is this likely just some quirk of Filmora? Is the application doing the resizing for some reason automatically, or can a camera resolution really have different choices built-in? Could it be that the camera really has two 320x240 choices and applications get confused and think they're the same one? Is there a way to exploit these multiple choices in general and actually get a webcam resolution to be zoomed in or out in some cases?