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

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

Hi Roland:
How does your rule of thumb formula work for slower scopes? For f/7 it seems
a bit on the long side: 14 x 8 = 112 minutes? I assume this is _without_ an
LPR filter?
Bert

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

----- Original Message -----
From: "Tim Hart" <Tim.Hart@haworth.com>
To: <astro-photo@seds.org>
Sent: Thursday, August 22, 2002 9:05 AM
Subject: Re: [APML] RE: Oh No! Kodak "Improves" Royal Gold


> I really like your rule-of-thumb formula...how did you come up with it?
>
> Do you have a formula for other films.....?
>
> Thanks
> Tim
>
> >>> roland@astrofoto.org 08/22/02 09:29AM >>>
> >>>>> "Rick" == Rick Kellogg <rkellog1@twcny.rr.com> writes:
> Snip...
>
> For E200/Elite Chrome, I know have a rule-of-thumb for a good
> exposure: T=2f(f+1), so at f/4 I get a 40 minute exposure.  Depending
> on sky conditions, adjust +/-50% (really dark skies, you might go to
> 60 minutes, mediocre skies stop at 20 minutes).
>
> roland
>
>
>
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