Acer Victoria wrote:
>OK, there's something I don't seem to get: why doesn't aperture and film
>speed affect exposure times for astro photos?
Acer,
Aperture and film speed DO matter. What does not matter is focal ratio
or change in focal length. Stars are mathematical point sources of
lights. No matter what the focal length of the lens their images cannot
be magnified. Therefore, exposure time does not vary with focal
length. A physically larger aperture does, however, allow more light
and shortens the exposure.
The reason you saw fewer stars after 30 seconds was probably fog. The
fog you saw at 5 hours started long before that.
Chuck Norcutt
Woburn, Massachusetts, USA
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|