[AZ-Observing] Re: NGC2264 (The Cone Nebula)
- From: "Bernard Miller" <bgmiller011@xxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Sun, 30 Dec 2012 13:03:19 -0700
Paul,
The technique I use to control the bright stars is to use the elliptical tool
to draw a circle around the star and halo (If you hold down the shift key while
using the elliptical tool is draws a circle). Then I feather it and use curves
to decrease the brightness. The other technique is to use the color range tool
to select the halo, expand and feather the selection and then use the
saturation tool to dial back the color saturation and brightness of the halo.
It is tedious if you have a lot of bright stars, but not too bad if you only
have one or two.
Bernard
-----Original Message-----
From: az-observing-bounce@xxxxxxxxxxxxx
[mailto:az-observing-bounce@xxxxxxxxxxxxx] On Behalf Of pulind@xxxxx
Sent: Saturday, December 29, 2012 9:32 PM
To: az-observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] Re: NGC2264 (The Cone Nebula)
Bernard,
Great shot. Regarding saturation and well depth, it seems inevitable to me
that bright stars will expose a group of adjacent pixels to their full output
value. That is, pixels that aren't supposed to get any light at all are often
saturated. A really severe case is 2nd magnitude Alnitak in shots of the
flame nebula. I found that 6th magnitude stars in the Rosette nebula (12-MON
for instance) saturated a disk 15 pixels in diameter in a 5 minute exposure at
f/3.6. This says to me that either a lot of stray light is hitting the
adjacent pixels, or light is being scattered within the silicon, similar to
halation in film. Trying to fix this in processing is challenging because
saturation is a non-linear process, not amenable to deconvolution. It will be
great to hear your findings on the subject.
Paul Lind
----- Original Message -----
From: "Bernard Miller" <bgmiller011@xxxxxxx>
To: az-observing@xxxxxxxxxxxxx
Sent: Saturday, December 29, 2012 12:38:34 PM
Subject: [AZ-Observing] NGC2264 (The Cone Nebula)
Hi,
The link below is to NGC2264, also known as the Cone Nebula. This image is part
of the larger Christmas Tree cluster and also includes the Fox Fur Nebula. This
image is a real challenge for my ST8300. The only drawback to the ST8300 is the
small full well capacity. Because of this, bright stars can get very
over-saturated. Keeping them under control is real processing challenge. I
hope you like it and comments and suggestions are welcomed.
http://www.azstarman.net/NGC2264.htm
Thanks,
Bernard
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