Philip P. answered 03/20/18
Effective and Patient Math Tutor
The times would be inversely related to the areas of the objectives lenses of the two telescopes:
pi·(1.22/2)2/pi·(4.26/2)2 = t/1.5
1.222/4.262 = t/1.5
Solve for t. The units will be hours. Multiply by 60 to convert to minutes. The time will be smaller because the larger telescope has a larger light gathering area.