Posts Made By: Greg Bradley

Tarantula Nebula taken with a Tak BRC 250, Apogee U16M camera, Apogee FW50 filter wheel, Astrodon 5nm Ha and O111 filters. 9 x 15 Ha (1x1) 8 x 15 O111 (2x2).

http://upload.pbase.com/image/103044509

Greg.

Ha 17 x 15 mins (1x1)
O111 5 x 15 mins (2x2)

Tak BRC 250, Apogee U16M camera, Tak NJP mount, Astrodon 5nm Ha and O11 filters.

PS2, Noise Ninja, Gradient Xterminator,

http://tinyurl.com/5lbpob

Greg.

I did this post as a reply on another thread and I think that it got lost.

Here it is as I think it will be of interest to many.

Hi Tom,

I researched this a bit more.

The following link shows a spectrum of colours and their associated wavelengths.

http://www.midnightkite.com/color.html

Ha light is 656.281nm. So per this spectrum it is an orangy red which
is often depicted in astroimages as a dark red, per this spectrum, incorrectly.

H beta wavelength is 486.13nm and per this spectrum is a light sky blue. But a Ha
filter would not be letting through any Ha beta as that is a long way from 656nm.
Assigning some blue to it would thus be twisting the data as it would really need to be
a H beta filtered image to get the correct H beta intensity. Also the blue assigned by
Photoshop would have to be that light sky blue shown in the link and not the heavy bright and darkish
blue Photoshop uses as default.

Also, I wonder what shade of "red" Photoshop uses when one assigns a channel to "red"?

"Red" of course is a scale from lightish tones to deep tones closer to infrared.The programmers of
Photoshop, perhaps arbitrarily, select a particular shade of red, which, in common usage considered "red".

Using the above spectrum then I wonder if it is possible to define which shade of red you want Photoshop
to use when it assigns red to Ha.

Photoshop has a palette of colours one can select for other actions. I wonder if
it lets you define a red from that palette for the purposes of assigning red to a channel.
I imagine it would if someone suffered through the Help file!

So in conclusion I take Ha to be a orangy red, not deep red, not orange, not pinkish but
a red leaning towards the orange side of the scale of red.

Using the above I have attached a Ha image I took of Eta Carina using a 12.5 inch RCOS and
adjusted the red channel assigned so that it matches quite closely the orangy red from the spectrum
in that link.

I think you'll agree this is not how it is normally represented. So I conclude that noone
is showing Ha in its more accurate colours and I will reprocess this Ha into an LRGB image to
see what it looks like and post it.
Greg.

I finally got some lovely nights at my dark site observatory in remote NSW Australia after
several months of disappointing conditions.

Tak BRC 250, Apogee U16M camera, Baader LRGB filters, Tak NJP mount.

LRGB 50 30 30 30

http://tinyurl.com/4h6lav

Greg.

A nice bright globular cluster.

Apogee U16M camera, Tak BRC 250.

LRGB 50 30 20 30

http://www.pbase.com/gregbradley/image/104250911

http://www.pbase.com/gregbradley/image/104251249 crop

Greg.

A spectacular southern object. Many times the size of the Orion Nebula and part of the Large Magellanic cloud which is quite close to the South Celestial Pole.

Ha O111 LRGB total about 7 hours.

Apogee U16M camera, Tak BRC 250 scope, Tak NJP mount.

http://www.pbase.com/gregbradley/image/104292003

Greg.

Here is a crop of an M42 image I took recently.

http://upload.pbase.com/image/104355948

Here is the whole image of M42 and The Running Man Nebula

http://www.pbase.com/gregbradley/image/104333829

Here is a crop of M42 by itself;

http://www.pbase.com/gregbradley/image/104334370

And here is a crop of the Running Man nebula:

http://www.pbase.com/gregbradley/image/104334268

LRGB 50 20 20 20 all 1x1 binning, Apogee U16M camera, Tak BRC 250 scope, Baader
LRGB filters and Apogee filter wheel. Tak NJP mount. Image taken from
my dark site observatory in NSW Australia.

Greg.

An icon in the Southern skies.

HaLRGB 45 30 30 30 30

FSQ106EDX with reducer and Apogee U16M camera, Baader filters.

http://www.pbase.com/gregbradley/image/106178773

Greg.

I received my FLI ML8300 camera a couple of weeks ago and here is my first tryout with it.

AP140, FLI PDF focuser, FLI filter wheel, Astronomik filters.

LRGB 15 15 15 15 at my dark site in NSW Australia.

NGC104, the 2nd largest globular cluster in our Galaxy.

http://www.pbase.com/gregbradley/image/106563547

Greg.

Here is a very pretty object in a fascinating part of the Southern Sky. It is part of the
Vela Supernova Remnant.

Tak BRC 250 with a FLI Microline 8300 and Astronomik filters.

LRGB 90 30 30 30.

Taken from my dark site about 2 weeks ago with excellent seeing.

http://www.pbase.com/gregbradley/image/107971610

Greg.