Re: [APML] saturn occ. time exp.

[Glenn Graham <glenng@synopsys.com>]

Very true about the difference in "good" exposure times for Moon and
Saturn. Along the edge of the Moon's terminator you can use a good
Saturn exposure time and still see some Lunar detail. Where are you
located? I would check, using a program like "The Sky", to see what path
Saturn will take with respect to the Moon and its terminator. If Saturn
passes near that point before or after it gets occulted, that might be
your best bet to get a pleasing photo. You can correct for some of the
over/under exposure afterwards if you scan and process the photo.

I got a nice video of September occultation using an STV camera. I have
a sped up version (every 100th frame) at:

http://home1.gte.net/res0jwg1/astronomy/index.htm

It might also give you a feel for the difference in brightness you will
have to deal with.

Good luck,
-Glenn


Bobby Middleton wrote:

> I'd suggest that you plan to use a high total focal length for this.
> Eyepiece projection is one way if you have the projection tubes. At
> short focal lengths you will be mis-matched on your exposures. Either
> the moon will be over-exposed or Sat will be under-exposed. High
> magnification at long fl's will get the two objects close to correct
> exposures. If you can design your system to get you 1/2 to 1 sec
> exposures that will be best. Use the hat-trick for your shutter to
> minimize vibrations For your instrument, an 16-18mm eyepiece with a
> 120mm projection distance will calculate at 1/2 sec exposure for a 200
> speed film; 1 second for 100 speed film.Bobby Middleton
> "To think that the eye could evolve by natural
> selection seems I freely confess absurd in the
> highest possible degree"    CHARLES DARWIN
> http://www.koyote.com/users/bobm/astro1.htm
>
>      ----- Original Message -----
>      From: Marios
>      To: astro-photo@seds.org
>      Sent: Thursday, November 01, 2001 7:08 AM
>      Subject: [APML] saturn occ. time exp.
>       Hi friends, I would like some advises for time exposures
>      for the Saturn Occultaion on the 3rd of November (this
>      Saturday) I will be shooting Prime Focus with an 8" f/5
>      F1000 Newtonian telescope. I will mount the camera on the 2"
>      focuser.Shall I use a fast film (800 ISO?) or a slower? What
>      would be the time exposures? Thank
>      you. Marios.www.CyprusAstronomy.com
>


--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
             Unsubscribe at <majordomo@seds.org>