From: Milton Aupperle <milton@outcastsoft.com>

Date: June 27, 2009 12:17:27 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Opinions on my Jupiter image


Hi Ray;


On 27-Jun-09, at 12:01 PM, Ray Byrne wrote:



Hi Guys,


I've uploaded an image of Jupiter into our files section, I'd like your opinions. I've posted it on Cloudynight's Solar System imaging and Processing Forum and had some positive criticism/advice but the chap making the suggestions is, I think is coming at it from a PC software perspective. He initially asked some specific data on stack sizes and the like. For those of you who don't frequent the forum here's how the thread has gone:


Give us some specifics, like : FPS, stack size, histogram settings, altitude of the planets etc.. It helps to evaluate the situation. Great image!!


Sorry about that, Here you go:


FPS: 30; Gamma 1.00; Brightness: 736; Stack size all colours 250 frames from 800 frames grabbed. Not sure of Jupiter's altitude but I'm at 51 degrees north. I used a Meade 2x Apo Barlow. The luminance was created from the green.


Someone correct me if I'm wrong, but you want to keep brightness at zero.max out gain and leave gama at the default settings. Keep the histogram around 240 to 250. Try that to see if it helps. 


By Histogram he likely means keeping the captured image brightness so that the maximum value of each pixel is 240 to 250 (which Astro IIDC 4.04.00 can do in real time and show you which pixels are over saturated based on your cutoff parameters in the Preferences Sheet) OR maybe he's talking about Histogram Level stretching in PhotoShop. It's not clear at all what he's jabbering about with Histogram.


If your at 51 degree longitude, then Jupiter when due south will be about 26 degrees above the horizon (that's 5 am MST here and I'm at 51° N latitude too).


The Brightness (gain) slider does seem a bit high too me, but it depends on many factors such as true focal length, desired frame rate and turbulence levels. A high frame rate allows you to capture big bursts of frame and may help reduce turbulence affects too.


HTH..


Milton Aupperle