[Prev][Next][Index][Thread]
Re: (meteorobs) Re:Fisheye lens
Becky wrote:
>Now I'm curious.........would a convex security type mirror work for this?
You know like the ones they use in stores to deter shoplifters? Or is it
too big?
>
>Becky Schultz
>
It's worth a try. I'm not sure if the curve is steep enough. I was
going to try one until I found out how much they cost. They come in a number
of sizes according to a local glass/mirror company. Also in plastic and
glass. If you have one or have access to one try it and let me know how it
works. The further the camera is away from the convex mirror the smaller
the central obstruction. The auroral all-sky camera used a four legged
support (like a tripod) for the camera. It was marked off in 15 degree or
so steps for reference marks. You could use a telephoto lens to get back
far enough but this may not be necessary. Just as long as the mirror fills
the camera frame. Your only trying to photograph bright fireballs so you
can use a small f-stop, say F-6.3 or F-8, and then your exopsures can be
quite long if your at a dark sky site.
Ed
------------------------------------------------------------------------------
Edward Majden epmajden@mars.ark.com
1491 Burgess Road Meteor Spectroscopy
Courtenay, B.C. http://www.serve.com/meteors/majden.html
CANADA V9N-5R8 Amateur Astronomy
------------------------------------------------------------------------------