From: Milton Aupperle <milton@outcastsoft.com>

Date: June 21, 2006 6:12:34 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Jupiter through my 6" refractor

Hi Alan;

On 21-Jun-06, at 11:07 AM, Alan Friedman wrote:

Hi Milton -

I checked - the pixel noise percentage is 3.7 for red and 2.8 for green and blue.

Gack!

That means your pixels are changing "on Average" by +/- 9.25 out of 255 for red and +/- 7.14 out of 255 for blue and green. In other words a red pixel might be 118 one time, then 137 in the next frame and anything in between that in the frame after that. And that's "on average", so we will have cases that are larger than that. That sort of makes it hard to do pixel matching for what is or is not a feature between frames.

I have not tried using white light luminance for Jupiter in a long time. I do shoot Saturn this way and I have tried binning for the RGB data - also using a shorter focal length and resizing the images for the composite - both work fine. With Jupiter so low in the sky there will be significant atmospheric dispersion that will blur an image captured over the full visible spectrum (I don't have a dispersion corrector - I guess this would be an option). I carry IR, R, G and B filters in my four position filterwheel - I need another hole to mount a clear filter. Thanks for the suggestions.

Correct me if I'm wrong, but I though you using the IR as Luma to create your LRGB images? Or are you just recombining the R G B channel movies and ignoring IR?

If your not using IR for Luma then my suggestion isn't of any use at all.

It might be interesting next your out with long focal lengths to try imaging the R G B channels in 2x2 binned mode with much lower gains to see if you get better results or not. The high gains are going to severely degrade the image quality. This would especialyl apply for much dimmer Saturn.

TTYL..

Milton J. Aupperle

President

ASC - Aupperle Services and Contracting

Mac Software (Drivers, Components and Application) Specialist

#1005 - 815 14th Avenue. S.W.

Calgary Alberta Canada T2R0N5

1-(403)-229-9456

milton@outcastsoft.com