Hello! I am planning on my first APO refractor purchase, looking to image deep sky (more or less wide field--that's what you get with refractors anyway) with my mirrorless (Sony FF stock, APS-C modded). I have a Star Adventurer currently, but can upgrade to something like Celestron Advanced VX or the like.
Here's my question:
In your experience, what focal length would you consider the most versatile, that is, will hit the most number of good quality targets if I were to only have ONE refractor, at least for the time being? In other words, the object, be it nebula or galaxy, would fit nicely in the frame and get some nice detail inside. Obviously, having the FF and the APS-C will give that extra reach, so its a benefit for me.
I think (Rokinon) 135mm and (Red Cat) 250mm might be too wide. Will focal length ~360mm be zoomed in enough to get the most targets? Or should I aim for around ~480mm? Not sure if going much deeper than that might be too expensive or difficult for a newbie to work with.
I just heard about the Red Cat 71... that might be something to wait for.
Anyway, thank you for the input in advance!