From: Mark Gaffney <markgaffney@mac.com>
Date: March 7, 2009 11:30:13 PM MST
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] More New Lunar Images..
Thanks Milton. I`ll write all these settings down so I`ve got it right next time I`m imaging the moon. As for DSOs I`ll need my PA right first anyway & I don`t imagine Celestron`ll have "All Star" fixed for the southern hemisphere `til the next upgrade of the firmware which may take a couple of months (at least?). Unless I brave drift aligning again in the meantime! If I can get the Mogg 0.3 reducer/extender to work along with the f6.3 Antares I should be able to get all of M42 in the FOV I think. I hoping the added length of the guider & visual back will enable focusing. At present only the 2, 0.6 reducers are focusing OK (that`s on a shipping container we have 50 metres from the scope). Mark.
On 08/03/2009, at 4:14 PM, Milton Aupperle wrote:
Hi Mark;
A few other suggestions from your log:
1) Don't set the pixel matching value (i.e. "Allow up to xxx.x
variance per pixel when matching pixel areas") to 0 or all you will
probably get is one frame stacked, which is what happened. As I
suggested in the manual, use a value in the range of 5 to 8 (see page
31 of the manual). I am using 6 for these lunar images I'm posting here.
2) Don't use Luma option for "Use XXXX color channel for sharpness
and alignment" when stacking, the answer why is on page 28 of the
manual.
3) Use an appropriate Gross alignment method (i.e Lunar/Solar or
Planetary) for your target. The log you showed me was set to
planetary, but I think you were processing Lunar movies? This also
affect the Sharpness estimates and histogram as we use a different
method for estimating sharpness for Lunar/Solar than we do for
Planetary.
4) Unless you had clouds causing the brightness to change AND a
perfectly polar aligned mount, don't use "Adjust pixel area
brightness if frame brightness changes." for lunar imaging. See page
32 for more info on this.
5) The only reason you should be using "Gaussian blur the frames used
for sharpness estimation & alignment" option is if you used really
high "Brightness" slider values on the camera controls. High
Brightness amplifies CCD noise and this will reduce it. Since you
were shooting the moon with a focal reducer, you likely had
Brightness set very low.
As far as DSO object exposure times, it varies based on the object
and the only way to find suitable exposures is trial and error. Once
you've done a few brighter objects it will make more sense. And don't
bother going after Mag 16 galaxies the first night, pick a nice
bright open cluster or M42 or whatever is conveniently high in the
sky and get used to simple stuff before going "deep".
Hope that helps..
Milton Aupperle
On 7-Mar-09, at 9:35 PM, Mark Gaffney wrote:
Hi Milton you like that "DomeZilla" region don`t you!! I guess you
mean the RGB saturation box? The images were that colour when taken-
perhaps not light enough, although I thought I was already being
gentle with the colour! If what you`re saying about your originals is
right they`re more grey than brown to my eye- must be a very light on
approach! You`re right I`ve got the "Sharpen the frames used for pixel
alignment" box & the "Sharpen frames by (High) amount before stacking
them" selected. I missed that bit about it needing to be very light.
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