Why is my video quality bad?

[eemuoy]

I have a Canon T6i with a 18-55mm and I've been filming using studio lights and a green screen. As a film student I've been taught to have specific settings, which is what I followed. I filmed in 1080p 60frames, shutter speed: 125, aperture as low as possible so 5.0, and ISO set to Auto because when I went off of auto, the lowest I could go to make sure my frame was properly lit was 3200 ISO. I also used manual focus with digital zoom to help me make sure it was absolutely focused. After filming, I checked my footage, and the quality was absolutely terrible. There was so much grain. Why is it like this? How can I improve it? I

I've used this camera many times on the green screen and it was fine so I'm not sure what the issue is now. 

[jrhoffman75]

If you need to manually select ISO 3200 to get proper exposure putting the camera in AUTO ISO without changing anything else just means the camera will now select 3200 ISO. That's why you have noise. 

[kvbarkley]

If you have to have those specific settings, then you will need to add more light to get a proper exposure.

[shoestring129]

I have the same camera and with really good lighting and have the settings set to that lighting and it still looks like it's filmed in 480p