I am in the process of switching over to narrowband imaging an plan to use the following:
Nikkor 180 ED
ZWO Nikon adapter & filter drawer (provides 56 mm back focus with filter)
7 nm Ha and Oiii filters - 1.25" using the ZWO 2" to 1.25" adapter inside the drawer
Skywatcher Star Adventurer
ASI120MM + mini guide scope
Does anyone see any potential pitfalls with this plan? My previous setup was using an AT60ED and Nikon D5300. While this was really fun, I seemed to hit a wall with OSC and my Bortle 8 skies. In my area even Bortle 5 skies are more than an hour away, so this is my plan to get better quality data from the comfort and convenience of my yard. I had initially been scared away for NB imaging due to the much longer exposures that most seemed to suggest would be required (5+ min) and my less than ideal mount, but after doing some research and maths I have convinced myself it should be OK...
Using Dr. Glovers ideal exposure time calc: Exp(s) = C (constant, using value of 10) * R^2/P, where R is the read noise (e-/pixel/s) and P is the light pollution rate (e-/pixel/second), I get a calculated ideal exposure using the Nikkor lens (@f/4) and the ASI183MM with a 7nm bandpass filter of right at 120s. This calculation is supposed to give a reasonable target exposure time where the read noise is swamped by the sky background.
I was able to get 2 min guided easily with the AT60ED/D5300 combo at an image scale of 2.24"/pixel, so I am confident that I can get at least this or more if needed at the 2.75"/pixel image scale that this setup would give. While 2.75"/pixel isn't ideal it's not much worse than I had before which gave good detail.
So again, does anyone see any large potential issues here? I've seen a lot of mention of the shallow well depth on the 183MM, should I be concerned about this shooting in Bortle 8 at 2-3 minute subs? I would plan to shoot 2-4 hours per night on each filter and then combine in post. Also I assume the 1.25" filters will be OK for 183MM with it's sensor dimensions.
Any input or tips for success is appreciated.