From: "Alan Friedman" <alan@greatarrow.com>

Date: June 21, 2006 9:29:54 PM MDT

To: <Astro_IIDC@yahoogroups.com>

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

Reply-To: <alan@greatarrow.com>

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

From: Milton Aupperle <milton@outcastsoft.com>

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?<

I create a luminance image from both the R and G images - usually a 50/50 

average of the two. Sometimes I will average data from the IR into the R to increase 

the signal and allow additional unsharp mask. 

It is important to note that the data in IR is in theory the lowest resolution of the 

four (IR, R, G, B) due to its longer wavelength. To follow, the B should be the 

highest resolution image. Unfortunately the seeing works in the opposite manner - 

the longer the wavelength, the less the image morphs from atmospheric 

turbulence. In practice, the blue stream is always the blurriest in my set. For Jupiter 

a luminance created from R and G will present an accurate aspect of the planet. 

This is not the case with mars - which has cloud activity that is only seen in blue. 

An R/G luminance for mars yields a somewhat dry and dusty image and misses or 

under-respresents limb hazes and cloud formations.

The IR produces a very similar image to R - usually with more contrast and lower 

gain requirement than the red. But on a night of fair/good seeing (5 pickering or 

better in my experience) the IR will clearly display less resolution than the R. I think 

you can see this even in the reduced size images in my jupiter from 6/12.

The high gains are going to severely degrade the image quality. This would 

especialyl apply for much dimmer Saturn.<

I will have to check the pixel noise percentage on a longer focal length stack. 

These short FL streams are some of the "prettiest" data I have used with Astro IIDC 

and I thought the image quality came out pretty nice.

Alan