From: Alan Friedman <alan@greatarrow.com>

Date: February 4, 2006 1:44:16 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Saturn at Opposition

Hi Duane -

I believe Milton posted a link to Wes' web index in an earlier post. He is an active participant in the Astromart Planetary Imaging forum (which is a great forum for this topic, BTW). His lunar work with an 18" Starmaster is the best I've seen from this planet.

I thought I would copy a post I made earlier today on the Astro-Physics forum. Seeing is huge, no doubt - but be sure to have a look at Damian's mars images from the UK in average - good seeing. There is hope short of lugging all your stuff down south!

I hope to have a website live by the end of this month - thanks for asking.

cheers-

Alan

ps - the whiner I refer to in my post below is me, not you!  8^)

-----------------------------

Hi Milt -

I think your comments are a good summary. In planetary imaging, seeing is still a

critical factor - but it factors differently than in visual because you can pick the

image apart into 33ms bits, choose the good ones and eliminate the bad ones. In

this way, the seeing is not a monolithic experience. In virtually every stream there

are images typical of 6/10 seeing and 3/10 seeing - the question is how many are

of the 6/10 variety in a period of time before features move and can no longer be

averaged to reduce noise. The Pickering scale as we use it for visual observing

does not really work well to describe limits for planetary imaging (I wonder how

many imagers begin and end their sessions with a star test - poor, fair, good, very

good might be just as useful).

While we often talk (and whine) about the seeing conditions it is important to

remember that very good imaging results can be obtained in fair-good seeing (5

-6/10). You need enough aperture for adequate light to record with a long focal

length. Assuming good processing skills, in conditions where 600 frames at 6/10

quality can be gleaned and averaged, the postion of the Encke division will be

recorded over a good section of the ansae of saturn's rings.

These conditions can drift in and out many times over a 30 minute observing

session and can be found during some part of the night in almost any location. A

big part of the challenge is getting out frequently enough to catch them. Damian's

images are truly spectacular - also remember that he has been out to image mars

more than 100 times during this apparition.

steady skies!

Alan

---------- Original Message ----------------------------------

From: "wilcoxmilton" <wilcoxmilton@yahoo.com>

I guess the difference must be that in imaging you get to stack so

many frames (hand picked?) that it effectively neutralizes the effects

of mediocre seeing?  At the eyepiece, I find it extremely difficult to

mentally register the detail available in brief moments of clarity (I

know I am not in the skill class of many of the visual planetary

observers here).