Weather forced reprocessing...

Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html

--
Pete
http://www.digitalsky.org.uk

"Pete Lawrence" wrote in message
...
Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html

--
Pete
http://www.digitalsky.org.uk

Nice images, Pete.

George

Pete Lawrence wrote:
Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html

Time well spent!

Davoud

--
usenet *at* davidillig dawt com

Yup, I've done that also. That's the upside of imaging; even when the weather
prevents more data to be gathered, you can always revisit some old stuff and
re-process.

I've even gone back on data from 1995 and reprocessed that to get more out of
the images.


Separate Topic --- the color in objects
---------------------------------------
One thing I do wish to debate however, is what exactly IS the right color for
objects?

First, let's get the "more red is better" argument out of the way. Most images
of deep sky objects, particularly gaseous nebula, taken with color film, are
biased to show reds more than greens and blues. The filters used by color film
happen to have the peak response for the red filter almost exactly at the
hydrogen alpha line, but the hydrogen beta and gamma lines, in the green and
blue wavelengths respectively, sit where the filters will not transmit them very
well. I wonder if colored filters for CCD cameras have the same effect? For
film, this biases the colors towards the red untruthfully.

When excited in a tube, hydrogen gas, when it is bright enough to see the glow,
looks pinkish, not reddish, at low excitation levels. When the energy is
increased, it becomes more blue or lavender in color.

When I was using a single shot color CCD camera with my telescope, I discussed
this topic in this newsgroup many years ago, and with visual observers, and the
consensus is that the color of gaseous nebula visually in large telescopes tends
towards green, and as the object appears brighter goes to pinks. I saw this
effect when I looked at M42 with a 60-inch Cassegrain reflector. I should add
that the colors are not heavy, fluorescent, gaudy things, but wonderful pastels,
shades of colors, shading mostly and gradually into one another. I wish to add
that some of the stars in the central region were definitely reddish or
surrounded by reddish halos. This experience caused me to lean towards tilting
the colors towards the green, and downplay them.

I didn't carry on this discussion with galaxies, but the experience with the
bias of the color with film has caused me to wonder. Is the core that reddish?
Should spirals show more blue overall?

Sincerely,
--- Dave Nakamoto
--
----------------------------------------------------------------------
Pinprick holes in a colorless sky
Let inspired figures of light pass by
The Mighty Light of ten thousand suns
Challenges infinity, and is soon gone




"Pete Lawrence" wrote in message
...
Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html

--
Pete
http://www.digitalsky.org.uk

Pete Lawrence wrote:
Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html



Pete;

I enjoy your images so much that I mount them as wall paper on my
notebook computer. Keep the good work coming.
Could you repose the Pleadies, a friend of mine would like to use it on
his computer.

Dave Nagel
nagel.david#sbcglobal.net (note the pound sign)

On Fri, 24 Feb 2006 12:54:23 -0600, "David G. Nagel"
wrote:

Pete Lawrence wrote:
Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html



Pete;

I enjoy your images so much that I mount them as wall paper on my
notebook computer. Keep the good work coming.
Could you repose the Pleadies, a friend of mine would like to use it on
his computer.

Dave Nagel
nagel.david#sbcglobal.net (note the pound sign)

Hi David,

No problem - I list all of my recent images (actually since April
2004!) he

http://www.digitalsky.org.uk/recent/recent_images.html

The Pleiades images are he
http://www.digitalsky.org.uk/DSO/M45-2005.html
http://www.digitalsky.org.uk/DSO/M45-2005-2.html
http://www.digitalsky.org.uk/DSO/M45-2005-3.html


--
Pete Lawrence
http://www.digitalsky.org.uk
Last updated 4th February 2006

"Pete Lawrence" wrote in message
...
Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html

--
Pete
http://www.digitalsky.org.uk


Thanks for sharing your hard earned images. Too bad there wasn't a lot more
like you.

On Fri, 24 Feb 2006 13:51:43 +0000, Pete Lawrence
wrote:

Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html

Thanks for the comments everyone. A new, larger, version has been
appended to the http://www.digitalsky.org.uk/dso/M31-2006.html page.
--
Pete
http://www.digitalsky.org.uk

"Pete Lawrence" wrote in message
...
On Fri, 24 Feb 2006 13:51:43 +0000, Pete Lawrence
wrote:

Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html

Thanks for the comments everyone. A new, larger, version has been
appended to the http://www.digitalsky.org.uk/dso/M31-2006.html page.
--
Pete
http://www.digitalsky.org.uk


Startling image from an avergae quality 80ED. Did you do that afocally with
the focal reducer?

On Sun, 26 Feb 2006 12:43:01 GMT, "Mike Thomas"
wrote:


"Pete Lawrence" wrote in message
.. .
On Fri, 24 Feb 2006 13:51:43 +0000, Pete Lawrence
wrote:

Weather's been awful in Selsey for quite a while now so I've been
revisiting some old images to try and improve them. Here is a rework
of an M31 shot taken last November. The original was a little blue and
fluffy.

The original is he
http://www.digitalsky.org.uk/dso/M31-2005.html

and the revised one he
http://www.digitalsky.org.uk/dso/M31-2006.html

Thanks for the comments everyone. A new, larger, version has been
appended to the http://www.digitalsky.org.uk/dso/M31-2006.html page.
--
Pete
http://www.digitalsky.org.uk


Startling image from an avergae quality 80ED. Did you do that afocally with
the focal reducer?

Prime focus with the focal reducer. There's a lot of processing
involved to pull out the detail to be honest. If you compare the
original frames with the finished result you'd be quite forgiven in
not believing it was possible to get from one to the other (in fact I
felt the same way just yesterday!). However, fortunately I have kept a
lot of the intermediate stages - like in real life, I don't throw much
away; a fact that drives my wife nuts ;-). It's possible to see how
the image has evolved over time. Most worrying of all is the fact that
I don't have a workflow - I feel quite comfortable with programs like
Photoshop and will apply processing to images a I think the image
requires them in order to get the best result. It should also be
pointed out that there are no quick fixes here. I arrived at the first
stage after many hours of work at the computer (using ImagesPlus and
Photoshop) [http://www.digitalsky.org.uk/dso/M31-2005.html] and it's
taken, probably in the order of 20 more to get to the final version
[http://www.digitalsky.org.uk/dso/M31-2006.htm]. I even spent another
3 or so last night tying to squeeze more out of it. When I'd finished
and compared the original finished version with the new process, the
difference was so subtle that it wasn't worth the effort spent to be
honest.
--
Pete
http://www.digitalsky.org.uk