From: Mark Gaffney <markgaffney@me.com>

Date: November 13, 2009 3:30:41 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: ST3 Pro Exposure calculator...

Milton, 

I know I`m just an armchair imager of DSO`s & perhaps an advanced beginner otherwise but I thought people might be interested in the process? Nor am I trying to push an unwanted expenditure of money on this software...it`s efficacy may be unproved in my case but I`m pretty sure there are many who are able to use it successfully. Here`s another screenshot in which I`ve added filters (a Luminance one is set here), altered the seeing index to "Good" & added a setting for "Bright Nebulosity". I`m afraid this calculator window (as I`ve set it) specifies a 0.33 reducer for M 42-another thing you advised me against.. if only to save me money! (I have the Meade one now)...Surely a one minute exposure, or 53 seconds as it says is "in the Ball park" for this subject (given the parameters) whatever the variability of the SNR values?Sorry the image is a little small this time. Opening it in "Preview" & zooming it is probably the best option..

Mark. 

On 14/11/2009, at 8:44 AM, milton_aupperle wrote:

Mark;

--- In Astro_IIDC@yahoogroups.com, Mark Gaffney <markgaffney@...> wrote:

-------SNIP

>I know you
> don`t set much store by such calculators Milton but it may be useful
> yet!

I'm not against anything.

However until you actually prove that these calculations are even vaguely meaningful by imaging one of these targets with their suggested exposures, your just wasting your time.

Hypothetical imaging doesn't put photons on the CCD. You only gain practical experience by going out and shooting targets in a methodical fashion, with plenty of notes so that you don't repeat the same mistakes over and over and over again.

HTH..

Milton Aupperle