Question about OAG

[lostone]

I have a quick question about OAG's in general. Yes I know some love them and some hate them.

I'm looking at getting an OAG for my RC instead of using a guide scope.
Once the Main Camera and the OAG are focused. How is the focus of an OAG affected when an autofocus routing in engaged and the focus has slightly change. Does this affect the focus of the OAG to be refocused or is it hands off after initial focus? I would really hate to have to go back out every 5 frames to refocus the OAG.

Mark E.

[KathyNS]

The OAG is focused by making its light path exactly the same as the light path of the imaging camera. As long as the two paths are the same length, anything in focus on the imaging camera will also be in focus on the guiding camera. So an auto-focuser will ensure that the guiding image is also in focus.