Hi folks,
If I replaced my 300mm f4.9 mirror in my xt12g with a 300mm f5 mirror, would that give me more back focus.
I don't mind if I have to use extension tubes.
I guess this will introduce other questions like will my secondary mirror be big enough to reflect all the light to the eyepiece.
Its just a thought as I'm about 20mm short of in-focus for my canon d700.
I did construct a t-ring adaptor that screws directly onto the focuser , this got me an extra 10mm in-focus, but I'm still short 10mm
Even with the primary mirror adjusted up as far as I dare on the collimating screws/bolts
thanks
James