Deep Corona Australis

[avandonk]

I wanted to find out what I could get imaging dim dust by collecting a lot of data. This data was collected on three different nights and the longer exposures were all collected near the zenith. At my latitude Corona Australis is at the highest point in the sky when at the zenith.

Exposures 80 X 15s, 80 X 30s, 80 X 60s, 58 X 120s and 38 X 240s. This is a total of 6.8 hours.

Canon 5DH, Canon 300mm F2.8L at f/3.5 with exterior aperture, fridge at -11C. All exposures at 1600ISO. Hutech LPR filter.
Images plus used to correct for flats and darks in fit form. Converted to tifs and upsized bicubic X1.6 with IP. Stacked with Deep Sky Stacker using Sigma-Kappa. The resulting five stacked frames used to tone map the final image in EasyHDR after using Registar to align them. PS used to tweak final levels.

The image is crop of the full frame as vignetting causes lower signal to noise and nasty colour gradients.

Image at native pixel size FoV 5.4 X 4.0 degrees 4.3MB.

http://d1355990.i49.quadrahosting.co...08/corausn.jpg


The upsized image 11MB

http://d1355990.i49.quadrahosting.co..._08/coraus.jpg


A dark sky site may give better results in a shorter time but this is as good as it gets at my backyard light polluted site.


Bert

[multiweb (Marc)]

Very nice Bert. Pinpoint stars all over and such contrast. Got that lens working beautifully.

[Paul Haese]

Nice image. Excellent when you consider the location.

[DavidU (Dave)]

Top image Bert. You do wonders from Melbourne.

[renormalised (Carl)]

Nice shot, Bert. Stars look great

[alexch (Alex)]

It is sooo nice, Bert. The exterior aperture is definitely worth it, all other aspects aside I find the nice soft halos around the stars much more pleasing than multiple sharp spikes of a stopped-down lens.

Cheers,
Alex

[RobF (Rob)]

Inspiring stuff Bert. You make this widefield work look far too easy! Thanks so much for showing us the latest adventure.

[strongmanmike (Michael)]

Nice one Bert, yes a dark sky would be great to repeat that under! Still, lovely and sharp and very starry...Fred will HATE it

Mike

[TheAstroGuy (Shane Ross)]

OOhh I really like this one,

Fantastic image, i love the blue in it and the dark lane with the Glob right next to it looks really good.

Thanks for posting this image

Regards

Shane

[gregbradley]

Another fine widefield 5DH image. Is there any advantage from using a 5D Mk11 over a 5DH do you think?

Your Canon lens does not seem to have any chromatic aberration. I just got a Pentax 67 300mm F4 and a Pentax 67 165mm F2.8 for my Proline.

I am getting an adapter made up so I can use it. I expect a certain amount of chromatic aberration from it so I'll probably get a UV filter and focus at every colour filter change.

Greg.

[mill (Martin)]

That is a top shot from Melbourne Bert.
How did you get that many clear nights ??
You must have a cloud pusher

[avandonk]

Originally Posted by mill

That is a top shot from Melbourne Bert.
How did you get that many clear nights ??
You must have a cloud pusher

I already had 40x(15s,30s,60s &120s) from the 15-05-2010 when CorAus was lower in the sky.
By watching the IR satellite movie on the BOM page you can estimate if there is a chance of even a few hours clear of cloud. A desperate man will resort to any means to collect some data when the Moon is absent.

On 8th and 9th ie Sunday and Monday just gone had some hours of clear sky and managed to get the rest of the data. There was a bit of cloud dodging as this tends to screw up autoguiding. I have a video feed of the finder scope to my computer screen inside so I know instantly if cloud has turned up from a nice warm room. Here is an animated gif showing what I can see in real time in the finder screen. The GstarEX is producing a new frame every 2.6 seconds. 550k

http://d1355990.i49.quadrahosting.co...08/finder1.gif


The finder zoom can be set so the field is almost exactly what the 5DH captures.

Below is the CorAus field and the Helix Nebula field. The finder is that sensitive that I can see the Helix Neb in real time. I have added a jpg straight out of the camera adjusted for levels.

Bert

[avandonk]

Originally Posted by gregbradley

Another fine widefield 5DH image. Is there any advantage from using a 5D Mk11 over a 5DH do you think?

Your Canon lens does not seem to have any chromatic aberration. I just got a Pentax 67 300mm F4 and a Pentax 67 165mm F2.8 for my Proline.

I am getting an adapter made up so I can use it. I expect a certain amount of chromatic aberration from it so I'll probably get a UV filter and focus at every colour filter change.

Greg.

As far as I know Greg the 5D MII has better signal to noise than the classic 5D even though the pixels are smaller. From what I have seen I would say better than a factor of two. Canon go to a lot of trouble to make their sensors from Ultra Pure Silicon to minimise hot pixels. The on chip electronics are also better.

In my opinion there is only one lens better on our planet than the Canon 300mm F2.8L (non IS) and that is the Canon 200mm F1.8L. They both only have slight astigmatism on very bright stars at f/2.8 & F1.8 at the corners. At f/3.5 the 300mm is almost perfect to the corners.

Bert

[avandonk]

Thanks for all the nice comments folks.

Mike if you take away the stars it would leave just a brown blobby thing.

I wonder how Fred does it?

Bert

[jase (Jason)]

Awe inspiring field of view Bert. Enjoyed the vertical presentation as opposed to the typical horizontal display. Very well done.

[AlexN]

More of the brilliant work I've come to expect from you Bert... Great job.... This really is one of those targets that lends itself to a very wide field of view.

[rcheshire (Rowland)]

Another interesting and beautiful part of the sky - no clue about the technical details at this stage - it's a desirable target, along with the snake nebula and rho ophiuchus... very nice indeed!

[Tom Davis (Tom)]

Nice capture of all that dust!

Tom