And a lot of information on Google is hearsay!
I wouldn't really bother with B&W film for star trails/night sky photography. It may look just a vast mass of twinkling stars, but if you do the task in colour you will see stars of many different colours from orange, to red, blue, white, yellow and the occasional green, and maybe even satellites. The Milky Way is also quite colourful; all this would be lost on B&W.
Any film can be used. 50, 64, 100. Certainly not 400 unless you want a short exposure of around 45 seconds (no star trails). Tungsten film can be used too for a striking blue rendition (my own choice is Provia 100F).
Short "morse code" star trails result from an exposure of 1 hour at shallow aperatures (e.g. f4.5-f5.6). Longer trails will be obtained over 2 hours or more at aperatures of f8 while the most star trails, and greatest depth will be obtained over long exposures of say 6 hours, no greater than f8. Use a camera that is all manual/mechanical. No metering necessary. Just wait until it's dark, aim to the north celestial pole (that's for northern hemisphere folks; the photo below is aimed at the south celestial pole.).
New Moon nights are best, but you can also get quite good images with a light crescent moon (but not in the frame as it will record as a blur). A sliver of crescent moon will cast a glow over the landscape which can be quite other-worldly.
A strong foreground or mid-range feature is usually essential for star trails to add interest and scale. Trees, rocks, buildings, waterfalls (these will record as a solid silvery blur) etc can all be silhouetted against the night sky and enlivened by judicious use of a spot-light torch (the photo below has been illuminated inside with lanterans, and outside by car headlights for 30 seconds toward the end of the exposure), etc. Only your imagination limits you.
A few cameras can be fitted with a data back that allows intervalometric photography*: you program in the self timer delay, the exposure in hours/minutes/seconds, number of frames and whether the sequence is repeated after a 2 hour break (by which time stars will be in a different position). Even double exposures can be quite striking and are well worth experimenting with.
It's best to camp out rather than hang around and get impatient for a trip back home in the dark. I always make a good night of it, keeping busy until it's too dark to see.
And finally, keep notes of what you are doing so you can refer to these when you get the results back.
1-old hotel on Silverton outskirts.jpg
Outback night skies,
Silverton, New South Wales,
* I have such a back fitted to my EOS 1N; I find a position in the bush nearby where I am camping, out of the range of campfire and torchlight,
set up the exposure and head back to camp. In the morning everything is done and dusted.
Last edited by Poisson Du Jour; 04-29-2013 at 12:43 AM. Click to view previous post history.