Daniel the same focal ratio, and a difference between the two of a mere 15% in aperture/focal ratio and 33% in light-grasp. Not a significant difference.
Changing the parameters by a factor of 2 is where it gets interesting - focal ratio, aperture or focal length.
Hence I’d say look for an 8” f4 or 5 Newtonian, or a 190 mm Maksutov Newtonian (Skywatcher and Orion made some suitable for imaging). The latter are rare but do work well, occasionally one appears secondhand.
|