[APML] FOCUS for Total Lunar Eclipse

["joe" <jmize@svic.net>]

Extending this thread, what would be the best method of focusing the Moon 
through a telescope for film images?  Focus on the limb or a compromize? 
Thkx...joe  :)


"May You Go Among The Imperishable Stars"

Joe Mize:     jmize@svic.net
StarFields Observatory   http://www.cav-sfo.com
Chiefland, FL    29:24'33.4"N    82:51'37.7"W
Moon Phase:     http://tycho.usno.navy.mil/cgi-bin/phase.gif

----- Original Message ----- 
From: "Stuart Heggie" <stuart.j.heggie@sympatico.ca>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Tuesday, October 26, 2004 5:38 AM
Subject: Re: [APML] Film Choice for Total Lunar Eclipse (warning! OT)


> Wade, this is very helpful, thanks! Now we must all do our utmost to get 
> the clouds to go away.
> Naturally it was clear as a bell last night!
> Stuart
> ----- Original Message -----
> From: "Thomas W. Earle" <twade@bmi.net>
> To: "'Discussion of Film Astrophotography'" <astro-photo@seds.org>
> Sent: Monday, October 25, 2004 10:19 PM
> Subject: RE: [APML] Film Choice for Total Lunar Eclipse (warning! OT)
>
>
>> Stuart,
>>
>> You should have no problems exposing at ASA 1600.  Do you have a
>> drive that compensates for the rotation of the Earth.  Better yet,
>> if you have a Lunar rate, use it.
>>
>> If you have no clock drive, here are the longest exposures you can
>> take according the Michael Covington:
>>
>> 350-700 mm 2 seconds
>> 700-1500 mm 1 second
>> 1500-3000 mm 1/2 second
>>
>> For critical work (i.e. no blur), divide these times in half.
>>
>> I'm not sure what f-ratio you'll be using; however, at f/5.6 a
>> relatively light total eclipse, is around 1/2 second at ASA 1600.
>> For a dark eclipse, you're talking 9 seconds.  The cool thing about
>> using a digital camera is you can experiment with your exposure
>> times on the fly. This allows you to find the perfect exposure.  We
>> who use film, have to hope and pray.:)
>>
>> Good luck,
>>
>> Wade
>>
>>
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