Re: [APML] Moon comparison with 3 films: eclipse prep

["Chris Cook" <ccjd@ix.netcom.com>]

Hi Jeff -

The one in 1993: http://www.abmedia.com/astro/planets/eclipse.html
was very dark as far as I remember.  A 64 sec exposure on 400 speed film at
f/6.3 would confirm this.  The eclipse back in 1989 was very bright.  A nice
bright red/orange.  A real beauty.  The eclipse in 1996 was sort of in the
middle of these.

As far as the S&T article, 5 min with a 24mm lens (for example) does sound
too short.  I have not thought through a sequence shot yet but I would take
a guess that 10 minutes would be more accurate.  The total time from the
beginning of the partial to the end of the ending partial is 3hrs 14min or
194 minutes.  If you exposed every 5 min, you would end up with 38 "moons on
the frame.  And from reading the article, the moon travels 45deg across the
sky during that time period.  With 38 moons, that translates to a moon every
1.18 deg.  With a exposure every 10min, that's a moon every 2.4deg.  I
think, if my math is correct?  10 minutes sounds better to me.

Chris

----------------------------------
Chris Cook
Astronomical & Nightscape Photography
www.abmedia.com/astro

-----Original Message-----
From: Jeff Ball <jeffball@zoominternet.net>
To: Discussion of Film Astrophotography <astro-photo@seds.org>
Date: Thursday, March 27, 2003 11:09 AM
Subject: RE: [APML] Moon comparison with 3 films: eclipse prep


>Hello Chris,
>Thanks for the info and the links.  Chris, how would you characterize those
>lunar eclipses with regards to "lightness?"  I know one was around the Mt.
>Pinitubo (sp?) eruption.  Thanks for the help.
>
>BTW, I don't know if I agree with some of the advice in the May issue of
Sky
>and Tel on how to shoot the eclipse.  I like the idea of multiple exposures
>on one frame of film to capture the eclipse sequence.  (Seems like we could
>do this digitally, either digicam or scanned film, without taking the risk
>of exposing only one frame for the entire night.)  The author, Roger
>Sinnott, recommeds a wide angle lens (not sure if he is continuing his
>afocal discussion) and exposing the frame every 5 minutes.  When I run this
>sequence scenario in The Sky, regardless of the lens used, you need more
>than 5 minutes for the Moon to clear its previous location and get a new
>isolated Moon in sequence.  Am I missing something on this technique?
>Thanks.
>
>Jeff Ball
>www.astro-photography.com
>
>-
>
>As far as predicting the brightness of the eclipse.  A lot depends on
>paticulate matter and clouds in the atmosphere.  Since there has not been a
>major volcanic eruption lately, I would guess the atmosphere is fairly
clear
>and the eclipse will be on the light side.  Another factor is how deep into
>the umbra the Moon travels.  With the upcoming eclipse, I think it travels
>more towards the edge of the umbra, again, pointing towards a lighter
>eclipse.
>
>Here are some of my lunar eclipse shots from past years if you're
>interested.
>
>http://www.abmedia.com/astro/planets/eclipse.html
>
>http://www.abmedia.com/astro/planets/lunar-1989.html
>
>http://www.abmedia.com/astro/planets/moon2.html
>
>Chris
>
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