Coal Sack Mosaic

[avandonk]

This is a mosaic of four panels. Plenty of overlap as any vignetting shows up on the seams with dim dusty areas.

FoV is 8.6 X 6.4 degrees. Carefully focussed with a Bahtinov Mask before collecting data.

Details for each frame.

Canon 5DH, Canon 300mm F2.8L at f/3.5 with exterior aperture and lens hood extension. Hutech LPR filter.

Exposures dithered 20 X ( 15s, 30s, 60s and 120s ) at 1600 ISO. Stacked upsized X1.6. Usual HDR method.

Most of the data collected near or at zenith.


Small image at native sensor pixel size 4MB.

http://d1355990.i49.quadrahosting.com.au/2010_05/CSK_S.jpg


Medium quality large image at X1.6 native sensor pixel size 8 MB.

http://d1355990.i49.quadrahosting.com.au/2010_05/CSK_M.jpg


High quality large image at X1.6 native sensor pixel size 18 MB.

http://d1355990.i49.quadrahosting.com.au/2010_05/CSK_L.jpg


The original tiff is 325 MB and looks better than even the large 18 MB jpg.

The Bahtninov Mask really helps to nail exact focus.

Bert

[jjjnettie]

A sublime image Bert. Beautiful.

[multiweb]

So cool. The high-res is remarkable. :thumbsup: There are a fair bit of Hii regions in there more pronounced at the bottom and the center right of the field. There is also a bright red nebula next to the jewelbox and a few small clusters lying around. Top shot.

[h0ughy]

my word there are a lot of stars there. tell the truth you threw some fine salt over a peice of black cardboard!! Awesome result Bert

[gregbradley]

Fabulous shot Bert. You really have that technique down pat. World class.

Greg.

[dugnsuz]

Lovely image Bert - such fine detail.
How do you combine the various subs - Avg, Median Adaptive add???
Cheers
Doug

[Tilt]

Very nice Bert, dark lanes galore!

Michael

[avandonk]

Doug I use Imagesplus to convert from RAW to FITS and correct for flats and darks. This is all done in fits form. It is far more accurate to correct with the raw data in fits form than interpolated anything else. I then stretch initially in fits form before converting to 16 bit tiffs. I then upsize the tiffs by a factor of 1.6 with ImagesPlus using cubic interpolation.

DSS is then used to stack the 190MB tiffs using Kappa-Sigma and RGB balance using the weakest colour channel as a basis for scaling.

I then save as 16 bit tiffs straight from DSS without altering anything.

The 15s, 30s, 60s and 120s stacked tiffs are then made exactly the same size and content with RegiStar. I then use EasyHDR to produce the final tone mapped image.

Apart from that it is really straightforward?????

It helps that I have a degree in Physics and have worked in Science for forty years. Apart from that I am guessing and use a bit of trial and error!

Bert

[dugnsuz]

Thanks Bert - food for thought.
I've always admired the sharpness of the stars you manage to end up with in your images. I'm getting really sick of using the Min filter in all it's incarnations to tame my stars - the stringy snot effect is not what I'm after. Will have to try your method in someway I think.
Cheers
Doug

[mill]

That looks really cool and shows people that the coal sack isn't without stars :eyepop:

[Bassnut]

Gaud, thats the 1st pic ive seen thats so large and so hi res and the stars are so small and the detail so fine that you HAVE to zoom in to start to see anything.

Amazing technicals Bert, and a tour de force in every respect, a masterpiece.

[iceman]

That's a stunning result, incredible effort Bert.

Nice work.

[strongmanmike]

The 18meg shot is amazing Bert, so many stars :eyepop:

Opening the 18meg file and then looking at it at 20% zoom it looks the best

Top work :thumbsup:

Mike

[avandonk]

I realized I had won when the piddly stars near the Coal Sack started to resemble the Scutum Star Cloud. More of that later.


Bert

[White Rabbit]

Nice work, I didnt realise that you could get LP filters for canon lenses. I've always wanted to get into wide field imaging but not have a lp filter for my canon has always stopped me.

I think that will be next on my list for my 24-105 lens.

Cheers.

[Dean]

Incredible amount of stars... In fact I was watching a show last night on cable called "Space" with Sam Neill hosting/narrating (great actor BTW) and he gave an idea of how many stars there are in the universe... Just count the number of individual sand granules on the entire earth, then multiply that by 1 million... so 1 million stars for each grain of sand on earth... thats incomprehensible if you ask me! But your image here makes that estimation appear very possible and valid :)

[tornado33]

Wow, most impressive, such fine, numerous stars and detail there.
Would look great printed to poster size.
Scott

[DavidU]

Your work is astounding Bert.
Always thinking aintcha !

[jase]

Excellent Bert. Your mosaic processing skills are on the money. Top work in matching the panels. Looking forward to your next project...I'm sure you'll beat me to it ;) Well done.