[APML] Magnitude limit and exposure

[centaurus_a@virgilio.it]

Dear All,

I'd like to try for the very first time to shoot prime focus.
Because I'm manual guiding I guess I'll try with a very fast film (any suggestion)
and a short exposure (not more than 20 minutes). Is there a way to calculate
which magnitude I can reach depending on the scope f/ratio, film, reciprocity
ratio and time? I already know I won't reach the sky fog limit, but I'd
like to give a try to see if I can manage at least focusing and guiding
to obtain a reasonable result on some object (any suggestion on a bright
target?)
My scope is a Vixen SP 102M (acromatic) f/10

regards,
Nicola
http://astrofoto.laza.it

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