[APML]: Exposure confusion- HELP!

[a5817394@mcmail.cis.mcmaster.ca (Rob Roy)]

Not sure if this can be resolved.  I shot half a roll of Ektachrome P1600
(my very first astrophotos) and impatiently cut off the piece and took it in
for dev.  I told them it was shot at 1600, but afterwards, no one could tell
me whether it was pushed x2 as per instructions to get 1600, or not.  So I
don't know whether it was done at 400 or 1600.

I hoping that someone with a "feeling" for exposures can tell from the
following data.  I'll understand if it simply is not possible to tell.

Milky way through Cygnus, slight light pollution:
 21mm lens f3.5 5min. excellent exp. black background
135mm lens f2.8 5min. a little overexp.
 50mm lens f2.0 5min. obviously overexp.

Milky Way through Cygnus, very dark skies:
 21mm lens f3.5 10min. excellent exp. black background
135mm lens f2.8 7min. excellent exp. black background
 50mm lens f2.8 7min. excellent exp. black background *** all exp. almost
identical.

Prime focus 8" SCT f10
60.6% 21 day Moon 1/250sec underexp.
60.6% 21 day Moon 1/500sec very underexp.
M11 & M17 10min beautiful pix, black background.

Any help will be appreciated.

Rob