Re: [APML] RE: Exposure formula. Was: Oh No! Kodak "Improves" Royal Gold

["Bert Katzung" <katzung1@attbi.com>]

Good information! I should have thought of Covington's calculator. The
"country sky with some glow from town" description sure fits my location and
the 1 hour matches my experience with E200.
Thanks....
Bert

Bert Katzung
katzung1@attbi.com
www.astronomy-images.com

----- Original Message -----
From: "Roland Roberts" <roland@astrofoto.org>
To: <astro-photo@seds.org>
Sent: Friday, August 23, 2002 11:32 AM
Subject: Re: [APML] RE: Exposure formula. Was: Oh No! Kodak "Improves" Royal
Gold


> >>>>> "Bert" == Bert Katzung <katzung1@attbi.com> writes:
>
>     Bert> My problem with 112 minutes is that on ordinary 200 or 400
>     Bert> speed film, I would get washed out by sky glow at 112
>     Bert> minutes without an LPR filter. I usually go for 60 minutes,
>     Bert> even with the filter and stack several. If you have a much
>     Bert> darker site, 2 hours might not be all that unreasonable.
>
> Sky conditions are the key.  I know my site and based on what I see
> (naked eye) there, I can roughly gauge whether or not an alternate
> site will be similar (e.g., when I went to the Summer Star Party in
> the Berkshires).
>
> I just discovered today that Michael Covington has a freeware exposure
> calculator (for Windows) where you can plug in your numbers.  For
> Elite Chrome at f/7 under "dark country skies", it says 2.4 hours.
> For "country sky with some glow from town" it says 1.0 hours.
>
> So my rule-of-thumb is really based on both the film and my location.
> FWIW, if I shoot from home (NYC) at f/4, it tells me I get only 1
> minute.
>
> roland
> --
>        PGP Key ID: 66 BC 3B CD
> Roland B. Roberts, PhD                             RL Enterprises
> roland@rlenter.com                     76-15 113th Street, Apt 3B
> roland@astrofoto.org                       Forest Hills, NY 11375
>
> --  APML Archives at <http://astro.umsystem.edu/apml/>  ---
>              Unsubscribe at <majordomo@seds.org>
>



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