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

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

Hi Jeff -

>Lunar eclipse preparation:
>I have been debating film vs. CCD for the lunar eclipse.  My problem is
that
>I cannot fit the full moon onto 35mm format with my AP 2x barlow.  I hate
to
>give up the image scale and go with prime focus.  With the 2x barlow, I am
>shooting with 100 speed film for the full moon at 1/30.  According to
>Covington, during a lunar eclipse, I am looking at using ISO 400 or 800 to
>get exposures in some reasonable range at f16.  Exposures with 400 ISO
range
>from 25 seconds for a light eclipse to 5-20 minutes for a dark eclipse.  Is
>there a prediction on the brightness of this eclipse?

If you start going over ~90sec at a long focal length, you will need to set
your mount to the "lunar" tracking rate.  If you leave it on siderial, the
moon will start to blur.

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

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




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