Hi Pete,
It sounds a bit exotic "Comet Halley in 1985/86 (on hypersensitized film)". Are you a retired astronomer ? A little bit too advanced to be an amateur astronomer, or ?
I wrote an article long ago about the astrograph we have nearby to where I live. When I interviewed the astronomers they explaind to me the work behind the photos they took, very interesting. No tiny 24x36 mm full frame sensors, more 180x180 mm or even bigger.
Here is my article which is now translated to English:
http://www.astrofriend.eu/astronomy/...strograph.html
Lars