As far away as water clarity will allow. I try to have at least 6 feet between camera and lure. I DIY'd an insulated hole cover that also holds the mo-pod(a must-have imo) and it keeps the hole from freezing too quickly since the camera hole is generally outside the tent.
The closer it is, the more chance of affecting fish behavior, and of having a fish wrap around the camera cord during the fight. Placing it further back also gives you a bigger sight window, which can be significant..
It's easy to get in the habit of keeping your lure in the view of the camera and ignoring the rest of the water column, so keep that in mind too.