From: "Duane" <macastronomer@mac.com>
Date: May 25, 2006 10:31:20 PM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: Been a while!
Thanks, and as always, your a wealth of info :)
I will probably try the heater as my Meade suffers from that in the winter too. Now if there
was something to keep the gears from whining when it gets that cold... :)
Duane
--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@...> wrote:
Hi Duane;
On 24-May-06, at 2:28 PM, Duane wrote:
Those are the tips I am looking for.
As for the dark subtraction, it seems to help with a strange effect
that fire-i board has.
There is a vertical seam right down the ccd, about 1/3 or more
down. The color/density
on one side of this line is slightly different than the other. I
haven't noticed it since I did
the dark subtract.
I think Alan also mentioned a fire-i he once had, did the same
thing. I don't know if he
ever tried a dark subtraction. If anybody uses this camera, I'd
like to know if yours has the
same problem.
That "vertical seam" is known as EM coupling noise. It shows up far
more pronounced when you have the "CCD Over Drive option" enabled. As
you change base CCD exposure or Camera Frame rate, the position of
the "vertical seam" shifts horizontally. At faster frame rates it's
closer to the center and at low rates it's closer to the left edge of
the frame. Once your below 133 ms / 3.75 fps, it's pretty well gone.
It's all dependent on how fast the frames are transmitted and slower
rates have less noise.
Basically it's due to the layout of the camera electronics on the PCB
and all the low cost cameras suffer from it, except for The Imaging
Sources cameras (DMK DMM DFM DFK DBK DBM 21F04 series), but they
aren't really "low cost" . The worse cameras were the iRez Stealth
which also suffered from "random" diagonal interference noise too
(see http://www.outcastsoft.com/AstroImages/MVMJS_04_03_28.jpg and
notice the diagonal marks on Jupiter's limbs). That is the main
reason we no longer officially support iRez.
And your solution to do a dark frame is a good choice and does help
out quite a bit. I also use that when I'm guiding especially in
Monochrome 2x2 binning modes with "CCD Over Drive option" enabled and
the gains cranked up. It eliminates the edge noise a lot and helps
Astro IIDC locate the star from the "noise".
I'll have to find some pure alcohol. I have a few motes and I think
they are coming from
the filter.
Most Drug Stores should carry 99% Isopropyl alcohol, but you may have
to ask them for it. They usually also have jugs of 99.9% pure
distilled water too for medical purposes (i.e. treating burns,
bathing wounds, eye wash etc.).
Drugstores are great place and is where I found a cordless gel pack
heater / cooler at a drug store, which has been great for doing
winter imaging. You toss it in a microwave, heat it up until it
nearly burns your hands and then put it on the back of the LCD
display to keep it from freezing solid and not updating anymore. It
worked for a few hours at around -30°C to -40°C to keep the LCD
above -20°C which is where it started freezing.
Sorry about posting. I'll refrain until I get something good :) or
with more questions...
Not a problem. And if you had not posted it, we'd never have gotten
into the discussion about what the "vertical seam" is or how to deal
with it.
Hope That Helps..
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@...
www.outcastsoft.com