With color films, watch out also for reciprocity failure! This can cause
ugly color shifts in the film. It's not necessarily the same for different
speeds within the same film family. An example is Elitechrome 100, 200 and
400. Elitechrome 200 (same as E200 professional) has the best reciprocity
of the three and is good to 10 seconds without correction. According to
the data sheets, the ISO 100 and 400 are good only to 1/10th
second. Sadly, Kodak has gotten much fuzzier about reciprocity failure in
their data sheets than they used to be.
In the Fuji, Provia 100F (RDP III) is good until 2 minutes without
correction, although by some reports there is some color shift at very long
exposures. It is one of the best of the chromes for super long exposures
without much trouble.
Bottom line: check the film data sheets to see what will happen when you
leave the shutter open for 10 seconds and longer.
Don't recall what color negative films are are good for long timed
exposures, but they vary considerably too.
-- John
At 23:42 8/12/01, Roger Wesson wrote:
Dear all,
A bit more about this astrophotography lark: first off, someone said to stop
down your lens for best performance. Very true, but if you just want to get
a lot of stars you definitely need your lens wide open. If you look at my
milky way shot you can see that there's uneven illumination and the stars at
the edges are definitely not spherical, but I'd much rather have that than
eliminate the aberrations and have less stars. And someone said the finer
the grain the better. True again, but to take full advantage of fine grain
you need to track the stars and expose for a long time. Without tracking,
fast film is the way to go.
Chris, you wondered if two-hour exposures wouldn't totally wash out - well,
if you use fast film they will do (I tried one once on 1600 film - that
might as well have been daylight and the moon wasn't even out!), but I've
had great results on Fuji Sensia 100 - for example
http://www.worldtraveller.f9.co.uk/travel/ohp/2001/photos/trails1.jpg. In
fact, this is probably the easiest way of getting satisfying star shots -
you can leave the shutter open while you sit inside with a cup of coffee.
(Or, you can justify all those OM bodies you have by leaving one on star
trails while another is doing some short exposures!)
Another couple of links you might be interested in - someone mentioned the
Aurorae Borealis: now is the peak of the 11-year solar cycle so they're
happening quite frequently. You can get the latest info and display
predictions at
http://www.spaceweather.com/
Also, if you want to get really into astrophotography, the Astrophotography
Mailing List can be found at http://www.system.missouri.edu/apml/. You'd
all feel right at home there, there's a major flame war happening right now,
actually...:) Most people on the list are pretty advanced but there's
generally help around for beginners as well.
And if you want to be inspired by the wonders of the universe on a daily
basis, have a look at http://www.star.ucl.ac.uk/~apod .
You know, I bought my original OM-1 purely to have a go at astrophotography.
Who'd have thought that I'd be sitting here 4 years later with three bodies,
9 lenses, various teleconverters and adapters, filters, and a box of some
5000 photographs...very few of which are actually astronomical! Damn this
zuikoholism...
Roger
PS Did anyone have any luck with the Perseids? It was cloudy as usual here
in London.
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