Attatched is a screenshot of a video I took the other day on a partly cloudy day. My T6i was shooting in 24 frames per second at a frame rate of 1/50 with an aperature of f11 and ISO of 100. The picture seems alright but is pretty grainy and disapointing compared to the HD quality I see others get out of this camera. I even took a picture of the same tree at the same time on my iphone and it came out way better. I'm hoping to get really crisp HD quality but can't seem to get it ever, even on perfectly sunny days. Does anyone know the problem??
Aside from the background being blown out, and over exposed, i do not see a problem. Remember, HD video brakes are more or less equivalent to a 2MP still photo. And, a 4K video frame is more or less equivalent to a 4MP still photo.
In other words, you only have so much resolution. As for achieving critical focus, this is one part gear and one part technique. Your camera is well suited for sitting on a tripod, and capturing video from relatively stationary subjects. It is not well suited for autofocusing while shooting video.
Moving the camera around to different subjects will usually require a focus adjustment. Capturing a moving subject, whose distance to the camera is changing, will usually require a focus adjustment.
While these shooting scenarios are challenging for your camera, and most especially the lens, it is not an insurmountable task. You just need to give some thought to your exposure settings. Exposure will need to be set and controlled manually. So, it is far easier to just put the camera on a tripod, and record a “stationary’ subject.