I'm new to AP world and I'm setting up my rig with HEQ5 mount, SW 72ED refractor telescope and Canon 70D unmodified DSLR camera. I'm getting started with APT and it seems to be very feature-heavy. I can see everyone doing guiding with an extra guide camera and scope, so I was wondering why not use the main camera?! To be clear, I'm not talking about off-axis-guiding where I can use an extra camera + main scope to do guiding.
On another note, how long of an exposure can I go without guiding? I heard that HEQ5 should do a fine job of tracking without guiding.