03-16-2017 08:15 PM
If you purchased the 1300D primarily for video, then I suggest returning it for a more expensive Rebel camera. The 1300D is designed to be an entry level camera, to teach the user about using a DSLR camera. It is not designed for high performance, and when it comes to video it lacks an external input for an external microphone. The bigger initial investment is well worth it. The best buy in the current Canon lineup is the EOS 80D.
Your aperture limitations are apparently being caused by your kit lens, the one included with the camera. Like the camera body, the kit lens is designed to teach you about lenses, and not so much for high performance. You can shoot video with it, but if you want wide aperture performance, then you will need to buy a wide aperture lens.