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Re: Physicists teaching astronomy



I think I've lost some of the posts to this thread, so this one may be
redundant -- also partly incorrect. I suspect 4 s. is much too short -- you
could try B&W film -- the fastest available and ask (do it yourself) the
processor to "push" it. There are formulae for greatly increasing the speed of
B&W film (exposing to Hg vapor is one, but difficult to control. For some time
one could find in thrift stores Polaroid cameras - their super fast film is
still available and some of the cameras' shutters (auto exposure) will stay on
for a long time in "low light". One model was used with the PSSC air table and
a strobe -- I don't remember how one kept its shutter open.

bc

"Polvani, Donald G." wrote:

Michael Edmiston wrote:

I have a nice picture of the planets taken with a 3.3 mega pixel digi=
tal camera. It appears at this URL...

http://www.bluffton.edu/~edmistonm/astronomy/

The file: five.planets.jpg is pretty much straight from the camera.

Although I am a camera novice, I was going to try and do a similar
photograph using only a simple auto-focus 35 mm (non-reflex)camera. By
disabling the flash, the instructions said I could get up to a 4 s exposure.
The "experts" said I needed, at least, 10 to 30 s exposure. I did see some
photos on the internet which used 20s. Clouds, and lack of a tripod,
prevented my attempt, so I never found out what would have happened at 4 s.

What exposure time was used for the above photos? Was a tripod used?

Don Polvani
Anne Arundel Community College
Arnold, MD