From: "Tim" <tjp314@pacbell.net>

Date: November 9, 2005 10:36:21 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Camera for guiding

David:

I won't speak for Alan, but I find I get my best results (in the poor

to so-so seeing I've had so far this apparition) with videos of

between 2000 and 4000 frames, the quality cutoff setting at 50-75%,

and the number of frames stacked at somewhere between about 200 and

1000, most often around 400 or 500.  And all of it depending on the

seeing.  Here, "poor" seeing is really awful, with turbulent "cells"

being fractions of a Mars disk across, so the planet morphs around

like a jellyfish or something.  Even my "average" seeing last weekend

had fast, fine grained turbulence blurring the limb and often

producing a double image of the north hood and south cap after

stacking and processing.  

When I joined the "Mars Flash" expedition in June 2001, I borrowed Don

Parker's 6" f/8, and shot Mars with a Nikon Coolpix 990 on a tripod,

afocally.  I was amazed at the quality of the images.  Mars may have

moved around a bit, but it always maintained a nice, round shape, and

the detail was always crisp.  ...they may look through a lot of

atmosphere in south Florida, but the whole state is "laminar"  ;o),

and even the fast-moving air masses above us weren't churning like

they do here in L.A.  

-Tim.

--- In Astro_IIDC@yahoogroups.com, "David Illig" <yag@d...> wrote:

Alan Friedman wrote, inter alia:

Here is a recent image taken in poor seeing and stacked in Astro IIDC:

http://www.geocities.com/alanfgag/saturn_103005.jpg

The image is nasty - grainy and over processed - but I did take

the time to compare the 

automated Astro IIDC stacking with hand selection in KIS. The

detail was identical either 

way. Oddly, the KIS stacks (saved as 8 bit pict images) had a

noisey interference pattern 

which was very difficult to deal with - this did not occur in the

stacks from Astro IIDC 

which were saved as 16bit Tiff images. 

Yes, but your worst is a lot better than practically everyone's

best. I enjoyed your amazing 

presentation at the Macintosh Astronomy Workshop and I have enjoyed

seeing your 

astrophotos on the Web. My wife says I am too hard on myself, but

every time I make a 

solar system image she says "That's great!" and I say "Yeah, but

take a look at Alan 

Friedman's Saturn (or whatever).

What you don't tell us is how many frames you typically capture,

where you set the 

confidence level, and how many frames your setting permits Astro

IIDC to align and stack. 

I know that that number can vary according to seeing, but some

ballpark figures would 

help me and perhaps some others who are trying to learn this art.

Thanks,

David