Video editing, After effect, Movies?

Hi, me and my friends are shooting a short film. When we edit the 2 minutes video in after effects it changes size from 150 MB to 2 GB. I don't know what is the problem, we only use color correction. I know some converters which make 2 GB to 25 MB, but after the quality of the video is very bad.

I don't understand. In Hollywood they use RED cameras and the size of the movie (1080p, bluray) is 25 GB. Any advice?

The cameras we use is Nikon D3100 and Canon SX 40 HS.

ALL editors who use After Effects knows that the compression in AE is rubbish as it is designed to keep as much quality in the clips as possible, meaning little to no compression. You could improve your file size by using 1920X1080 (or whatever size your footage is shot in) and selecting H.264 and making the audio AAC. But after that you will still see a huge rise compared to your original file size. I use Handbrake to compress my files which also converts it to MP4 or MKV which is better than the default MOV files.