Which Canon F-1?

I have a Canon A-1 camera and already have the T Adapter.
I heard that the best camera to use has a mechanical B setting. My A-1 does not.
I want to get a F-1, but there are 4 different models. Which one is best for astro use?

There are really only two versions of the F-1, the old (F-1) and the new (F-1N). There may be minor variations but the are only two basic F-1's. I use the F-1N for astrophoto but it's not the best candidate. If you don't already have one, I would suggest either an older Nikon or the Olympus OM-1. Both have mirror lock-up. That's almost a "must" for lunar and planetary photography. Also, the battery needs to be removed from the F-1N in order to use the mechanical B setting. With the battery in, the B setting will quickly drain it. I don't know if the battery needs to be removed from the older style (F-1). There are a couple of focusing screens that help in low light, high magnification focusing. They are very difficult to use in the very low light conditions of DSO photography. I decided that the Stelleto knife edge focuser is superior and is a heck of a lot cheaper than the F-1N. (Actually, I use the ronchi screen instead of the knife edge).

Regards,

Marv Johnson