From: Milton Aupperle <milton@outcastsoft.com>
Date: April 13, 2008 7:50:09 PM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Lines of Saturn
Hi Phil;
That really looks like fixed pattern EM camera noise or EM interference on the cables. Does it show up in single frames or not, because it should show up everywhere and usually is quite consistent if the camera has reached thermal equilibrium. Was the camera powered by the FireWire Cable or an external source? Has the FireWire cable been damaged or been treated roughly (i.e. accidentally slammed in a door for example) lately too? And is it repeatable in doors with the same set up (i.e. same high gains) or not? You can pick that out if you point it at a bland uniformly lit surface (i.e. wall) and then adjust the exposure until it's around 50% gray.
I've seen it (at a broader frequency) in all the low end Unibrain type cameras, especially when the gains are cranked up really high. For example look at the Jupiter disk in this image
http://www.outcastsoft.com/AstroImages/MVMJS_04_03_28.jpg
and you can see faint tightly spaced lines at around 50 degrees and also to a lesser degree in the Saturn image too. Also when I used to image with Analog Cameras (.e. EXHad ones), they were exceedingly susceptible to external power source variances and when they heated up the line pattern would oscillate all over the place.
Hope some of that helped..
Milton J. Aupperle
President
ASC - Aupperle Services and Contracting
Mac Software (Drivers, Components and Application) Specialist
#1005 - 815 14th Avenue. S.W.
Calgary Alberta T2R0N5
1-(403)-229-9456
www.outcastsoft.com
On 13-Apr-08, at 6:54 PM, Phil Houston wrote:
Milton,
Do you have any idea what could produce the diagonal lines in the
image of Saturn? (link below) I have noticed this effect every so
often in the past but last night, when seeing was good, most of the
longer video captures (2000 frames) produced this effect when stacked
and processed. I have not changed my processing techniques and some
images do not have the lines. I've exaggerated the sharpening to
show the lines more clearly in the linked image and the capture
settings are listed below.
