From: "Milton Aupperle" <milton@outcastsoft.com>
Date: April 22, 2008 10:15:46 AM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: Astro IIDC dark frames and "Use Sharpness for Capture" issues
--- In Astro_IIDC@yahoogroups.com, "doodlebun" <gbleser@...> wrote:
In the manual Milton states that Dark frame subtraction is really only
appropriate for 1 sec exposures or longer. Does this mean that I should
just forget about making dark frame movies for Planetary imaging?
Yes, your not really gaining anything with dark frames for those
camera. And Dark frames are mainly for Deep Space Objects.
I suppose I should have the box checked for automatic hot and cold pixel
subtraction, assuming my MacBook is fast enough (you mention the CPU
load).
Unless your seeing hot (bright stuck) and cold (dark stuck) pixels I
wouldn't use it as it uses up a lot of CPU cycles. Agian, it's
primarily for DSO objects Or if your camera has a lot of defective
pixels which becomes really noticeable as you increase the gains.
Also I notice that if when capturing images of Saturn I don't seem to
be able to "Use Sharpness for Capture" option. The movie starts but no
frames are captured, implying that nothing "is good enough" for the
software! I am using the default settings. Perhaps you can advise.
What you missed is that you need to enable what it is accepting or
rejecting as far as frames go by clicking on the "Sharpness:" pop up
menu and select the "Pixel Edge On" menu item. (see page 64 and 65 of
of the manual). If that's check marked, then is will indicate what
frames it is rejecting as not good enough by displaying the word
"REJECTED" in the video preview window.
Also you can't adjust exposure, brightness or color gains after you
have estimated your "sharpest" frames. As that will throw all the
frames into the rejected pile. You might want to increase the number
of frame sits averaging too, which again depends on how turbulent your
skies are.
And it really won't work well if you have lots of turbulence or if you
have very high brightness / gains set. It primarily was designed for
higher contrast objects like the moon or a limb or other features.
HTH..
Milton Aupperle