Doug, here is a table that might help. Otherwise Peter Zelinka on You Tube explains the formula in his video choosing your first dedicated astronomy camera.

--
Harry
Vero Beach, FL

Mounts: ES iExos 100-PMC Eight
Scopes: ES  ED80CF, ES AR102,  Meade ETX 90 EC (Deforked)
Guide: ZWO 30mm Mini, ZWO ASI120MM-Mini
Software: ASIair Pro, iPad Pro, MacOS, Starry Sky Stacker, Affinity Photo, Lightroom,  SkySafari Plus
Cameras: Nikon D600, D5500
Misc: ES USB Power Bank, Rigel QuikFinder, 0.8x Focal Reducer
Filters:  Optolong L-Pro, L-eNhance