I've got an equipment question that I'm sure has been asked and answered before, I just haven't been able to find the question/answer after a few days of searching.
BLUF (bottom line up front): I'm not sure where the focal plane is for my Celestron GPS C9.25 telescope with & without its f/6 reducer (NOT the EdgeHD), to enable setting spacing for my ASI1600MM camera setup.
I've had the scope since around 2012, but it's spent most of its life int he garage collecting dust. I did some basic astrophotography with it in the past with DSLR cameras, but nothing too dedicated. I decided this past winter to pull it out and dust it off (so it's probably my fault for all the bad weather this winter, sorry). This spring I was able to stumble across an amazing find (through a friend) on the 1600mm pro and couldn't pass up the deal. After going through the instruction manual, and lots of online digging, I can't seem to grasp where my focal plane is, or how to calculate it. I came across a thread about a c925 HD and its focal plane, but nowhere did they say where they got the info.
And how accurate does the spacing need to be? The thread (link to thread) about the EdgeHD talked about being able to adjust the focal plane with the focus knob - which makes some sense to me.. i'm must not sure how close I should try to get once I'm able to figure out the distance..
Any help/guidance/assistance would be appreciated!