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(meteorobs) Camera Exposures
In a message dated 98-04-16 10:20:31 EDT, you write:
<<
Shorter times, such as ten or twenty minutes give a less cluttered
image, but do try some 40 and 60 minute exposures. These will give you
a better feel for what you prefer and how the film reacts.
>>
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From a dark moonless night, I recommend making exposures at least 30 minutes
long. Ten and twenty minutes can cause a lot of needless interruptions if you
are recording meteor data as well. The same information about a meteor's
position can be determined from an unguided photograph with a short exposure
as well as for a long exposure. Just ensure that you write down accurate
start/stop times and meteor appearance times as close to one second as
possible. Now if a bright meteor crosses your camera's field, then stop the
exposure as soon as you can.
If you are photographing under brighter conditions such as with a full moon,
make your exposures no longer than 10 minutes with 400 ASA film. Any longer
the negatives will become "bullet proof". Aim the camera generally towards the
north for most places during a full moon. It will be the darkest part of the
sky. Just be aware where that dark spot is when you trigger the shutter. Under
these conditions, I wouldn't worry about where the radiant is at. You just
want to avoid that bright moonlight.
If you are exposing for a possible Meteor Storm such as the Leonids, Start out
with exposures of 5 minutes. If activity seems to be increasing dramatically,
make exposures 2 minutes long and record accurate start/stop times. I highly
recommend having a tape recorder near the camera to talk your times into..dot it
will save you some mental anguish.
For meteor work, I highly recommend only black and white film. Color is more
expensive. From what I understand, Magnitude determinations cannot be made
with color film...only black and white.
George Zay