I am creating a video with a mixture of video clips/still photos.

Can someone guide me on the size of photos that I should use.

For example the images have been shot with a Canon and are 6000 x 4000 pixels. I will want to do a bit of panning and zooming in and out etc. But are these too big for say a 1920x1080 video? Should I reduce them down first?

I think I have read somewhere that images should be approx 2x the video size to allow for panning/zooming etc but anything bigger creates a big file and slows rendering.

Can you help please?

Thanks