I'm not exactly a beginner, but I felt that this question belonged in the beginner forum.
It is galaxy season currently and I my main imaging scope and camera aren't generally well suited for galaxies. With the frankly HUGE pixels and the relatively short focal length (650mm) of the scope, it is generally not long enough to capture much detail. Ideally I would either get a longer scope, or a camera with smaller pixels, but budget is a little tight at this present moment so that's not an option for this season. Maybe next year. I do have a 3x barlow, but imaging at f/15 is a bit much even for me and I don't need THAT much more focal length.
So the question is this, the barlow lens element comes off of the barlow I have and I could easily screw that onto a 1.25" nosepiece for my camera to reduce the effective amount of magnification. The good thing is that the barlow will make it easier to reach focus with my DSLR on my newt, but the bad part is, I'm not sure exactly how much moving it closer to the sensor will reduce the magnification factor. Is there some formula I can use to determine barlow distance from the sensor vs effective magnification? And before anybody says that you shouldn't barlow for imaging, I KNOW this is mostly an experiment and I just want to know what effective focal length and f-ratio I will be working with.
Thanks in advance!