From: Alan Friedman <alan@greatarrow.com>

Date: March 29, 2009 9:06:58 PM MDT

To: Astro_IIDC@yahoogroups.com

Cc: macastronomer@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: weekend solar images


Hi Milton,


Thanks for the note. Apologies for not providing more technical info - I am really an image person at heart (but I think you already know that!).


The set-up uses the A-P stowaway (FL=450mm) and the Baader FFC with a 2.5 inch extension. I've not measured it exactly but I think the effective focal length is in 1500-1600mm range. Settings vary with each, but a good average is:

exposure: 23ms

gain: 600

gamma: .9


The captured streams are 600-900 frames in length - 100-150 frames are selected for stacking. Seeing is very poor overall, but there are a small number of sharp frames in each stream. Anticipating the dwell moments between high turbulence while capturing and then evaluating and hand selecting the data for stacking are the two most challenging parts of the process.


For those who might be interested, I will be doing a presentation on solar and lunar imaging techniques at the Mid-West Astro-Imaging Conference in June.


best wishes,

Alan



On Mar 29, 2009, at 9:15 PM, Milton Aupperle wrote:

Hi Alan;

Nice Shots..

What sort of focal length are you using? It would be nice to see some of the technical details.

TTYL..

Milton Aupperle

--- In Astro_IIDC@yahoogroups.com, Alan Friedman <alan@...> wrote:
>
> Hi all,
>
> I had a chance this weekend to capture some nice prominences on the
> edge of the sun:
>
> http://www.avertedimagination.com/img_pages/tsunami_prom_20090328.html
>
> sunny skies and best wishes,
>
> Alan
>
>
> Alan Friedman
> avertedimagination.com
>