Crux to Carina

[Ryderscope]

It must be cloudy at the moment as I am finding myself reprocessing old data ;). The case in question here is a wide field shot encompassing the field Crux to Carina. The data set was captured in July 2013 and originally processed using Image Plus software for calibration, registration and stacking and Photoshop for non linear stretching and processing.

The posting from 2013 on Astrobin can be found here. (https://astrob.in/48043/0/)

I was curious to see whether using a dedicated platform such as Pixinsight combined with an additional seven years of staring mindlessly at a computer screen whilst processing images would help with improving the final result :D

Here is a link to current revision of the image on Astrobin. (https://astrob.in/lt61gx/0/)

I'm happy with the result from this re-process. Additional detail has come through and the star field and objects therein are much sharper and better defined. There is improved depth in the image as well so that it withstands pixel peeping a little better.

The field view covers 25 degrees from the constellation of Crux (Southern Cross) on the left hand side of the image to the Eta Carina Nebula (NGC 3372) on the right hand side of the image. There are a number of other objects visible as well including the coal sack nebula, the dark nebula adjacent to the Crux and other smaller nebula in the field of view.

The image was taken with a Canon 60Da and 50mm lens @ f4.5 and is comprised of 20 subs of 180 seconds taken at ISO 800.

Comments and critique welcome.

CS,
Rodney

[multiweb]

Nice widefield Rodney. Gotta love dark skies. :thumbsup::thumbsup::thumbsup:

[Ryderscope]

Thanks Marc, the data for this image were captured at the ASNSW site Wiruna at Ilford which makes for very nice skies particularly in the winter.

[Placidus]

I opened the two versions each in its own window, and blinked back and forward between them.

Both are excellent, but I reckon the older version is actually the more engaging. More contrast.

Mend my rotten ways. Tell me what I should be seeing.


Very best,
Mike

[Ryderscope]

Interesting it is when trying to quantify why one image is better than another so thank you for the challenge. To assist with this I had to register and crop the current and previous versions to make sure they matched exactly. I've attached a registered/cropped version of each image zooming in on the area around the Eta Carina Nebula and the Lambda Centauri nebula. This also brings into play the open cluster NGC3532 at the top of the image and the asterism/cluster at the bottom surrounding theta Carina.

Why do I feel that the reprocessed version is better than the original?
This is what I see:

- The dense star field of the Milky Way is better resolved and therefore more prominent and obvious as a continuous band of stars. The Milky Way in the original image is more sparse and the stars and not as well resolved. Zooming in on the Milky Way star field in the reprocessed image resolves many stars that are not well displayed in the original version.

- The dark nebula that are present in the image are more prominent against the background of the dense Milky Way star field.

- The individual stars in the open clusters are displayed as finer points of light with improved colour saturation.

- The Ha in the nebulae is more consistent and evenly spread without gaps in the structure which are present in the original image. There are greater areas of extended nebulosity that are not present in the original image.

- The core in the Eta Carina nebula is blended in with the rest of the nebula. The original image had a very hard border between the core and the surrounding nebula.

- The stars are sharper and have more distinct coloration in the reprocessed image.

- There is a grouping of nebulae around NGC3603 which are barely visible in the original image but stand out quite well in the reprocessed version.

I can see your argument regarding the better contrast between the images. I do feel though with images that contain dark nebulae, particularly Milky Way fields, that we shouldn't push the black point too much. The dark nebulae are features in their own right with distinctive colouring that I feel adds to the aesthetics of the image.

So there you have it. I just feel that it brings out more detail and better coloration than the original. And - I need an excuse to do something with all these clouds about :D

Clear skies,
Rodney

[Geoff45]

Nice wide field there Rodney. Reprocessing is always a good idea. Amazing how our skills improve over the years

[Ryderscope]

Thanks Geoff. This was one of the few that I did at the time for which I grabbed a reasonable amount of data to work with (20 subs).