The big Kahuna

[Peter Ward]

Finally! Eta Carina...with colour.

Scaled 50% (sorry Marcus!)

Warning...over 2 meg download. Not i-pad friendly.

Two panes of a 4 panel mosaic (blue data holes yet to be filled)



The link is here

[alpal]

Very nice but yes - the blue is missing.
Did you see my recent pics?
I was using a standard DSLR - unmodded / no filter,
& there was plenty of blue information.
For some reason other people are getting nearly all red for Eta Carinae.

[gregbradley]

Yep that's a beauty. You seemed to have captured a lot of stars and lots of really faint ones. Star sizes are very impressive. So tiny. That is an elusive goal. Star shapes and sizes was one concern I had for the RHA but it seems to be unfounded.

How do you think it compares with an APO? The main difference I can see in this image is the number of fine stars that most likely would not show up in an APO and the star sizes which even for an APO are very small.

I suppose also you got the detail much faster.

Greg.

[Peter Ward]

Originally Posted by alpal

Very nice but yes - the blue is missing.
Did you see my recent pics?
I was using a standard DSLR - unmodded / no filter,
& there was plenty of blue information.
For some reason other people are getting nearly all red for Eta Carinae.

Appreciate the feedback ,but I suspect you'll find DSLR's (not just yours) are missing a serious amount of deep red....due their IR blocking filters.
Hence they paint Eta with way too much blue/green.

Originally Posted by gregbradley

Yep that's a beauty. You seemed to have captured a lot of stars and lots of really faint ones. Star sizes are very impressive. So tiny. That is an elusive goal. Star shapes and sizes was one concern I had for the RHA but it seems to be unfounded.

How do you think it compares with an APO? The main difference I can see in this image is the number of fine stars that most likely would not show up in an APO and the star sizes which even for an APO are very small.

I suppose also you got the detail much faster.

Greg.

Thanks Greg.

The star sizes are so pristine on the RHA that I'm finding I can pick even a few thou shift, due focuser orientation changing, as the scope moves during the night.

I think star sizes are smaller than say an AP155 APO...but only just. Then again at F3.8 this scope does test my ability to focus, hence I may need to migrate to an electronic focuser to know for sure.

The big difference I am finding is it captures equally good data compared to the APO, by virtue of its aperture, in about 1/4 of the time.

Colour correction is superb, with very consistent star sizes from SII through to Blue filters....

Lastly....The scope is so good it shows small homogeneity differences with various filters...with some small sections of the field having odd shaped stars that in effect, go against the grain, so to speak.

[stardust steve (Steve)]

wow love it i like the dark patch so black below the core? i think it is. And all those different coloured stars just ad to the spectacle. The star count must be in the 10s of thousands if not 100 tho ship loads any way. So many!
Focusing system: hairy eyeball and steady right hand.
Processor by Intel.
Redback Beer by Matilda Bay....
Great image.

[Peter Ward]

Originally Posted by stardust steve

wow love it i like the dark patch so black below the core? i think it is. And all those different coloured stars just ad to the spectacle. The star count must be in the 10s of thousands if not 100 tho ship loads any way. So many!
Focusing system: hairy eyeball and steady right hand.
Processor by Intel.
Redback Beer by Matilda Bay....
Great image.

Thanks Steve,

I've now uploaded the complete mosaic. Same Link as before

It's big! (3 meg... i-pads chuck a wobbly )

Eagle eyed star-spotters will note the odd vertical blue spikes coming off brighter stars toward the lower left.... these are due my mount reaching its western limit a few seconds before the blue exposure ended

Looking outside could be a while before I can replace the dud data.

[multiweb (Marc)]

Gorgeous colors and flawless stellar profiles. One for the cool(er) wall.

[Octane (Humayun)]

Oh, my.

That is simply incredible, Peter. Wow!

It reminds me of celestial icecream, or fairy floss, or something.

Just sensational.

H

[Peter Ward]

Originally Posted by Octane

Oh, my.

That is simply incredible, Peter. Wow!

It reminds me of celestial icecream, or fairy floss, or something.

Just sensational.

H

Thanks H. Actually its a bit too pink...I suspect I will have to make many tweaks to nail it...

Originally Posted by multiweb

Gorgeous colors and flawless stellar profiles. One for the cool(er) wall.

Merci beaucoup ! Reminds me..must watch Top Gear recorded last night

[alpal]

Peter,

Appreciate the feedback ,but I suspect you'll find DSLR's (not just yours) are missing a serious amount of deep red....due their IR blocking filters.
Hence they paint Eta with way too much blue/green.

Hi Peter,
I don't agree.
The DSLR is made to show what the human eye can see.
The human eye can't see all that red created by the infra red spectrum.
It depends if you want to see all the infra red in false colour.
The DSLR is giving you a true picture.


Not only that - what happened to all that blue information?
It's there because my camera recorded it.

Look at the blue in my pic:

http://i262.photobucket.com/albums/i...S_PS_PS_21.jpg

[Moon (James)]

Love it!

[Peter Ward]

Originally Posted by alpal

Peter,



Hi Peter,
I don't agree.
The DSLR is made to show what the human eye can see.
The human eye can't see all that red created by the infra red spectrum.
It depends if you want to see all the infra red in false colour.
The DSLR is giving you a true picture.

Not only that - what happened to all that blue information?
It's there because my camera recorded it.

Your DSLR camera has quite low QE at the critical hydrogen-alpha wavelength that dominates this nebula.

It is very visible to a warm human eye (being the very same wavelength that H-alpha solar observers view ) but it is outside (or very nearly) the gamut of colours a DSLR can capture with good QE.

Nothing false about. Suggest you Google David Malin's images of this object.

DSLR's simply can't see that part of the spectrum well and bias the result as best they can, ending up way too cyan.

Hope that helps.

[TheDecepticon]

Certainly is an awesome field of view!

Will be great to see it finished. Well done!

[alpal]

Hi Peter,
David Malin's images seem to be all red too.

What about this image?

http://www.wolaver.org/Space/carinanebula.jpg

http://www.wolaver.org/Space/carinanebula.htm

This image shows a giant star-forming region in the southern sky known as the Carina Nebula (NGC 3372), combining the light from 3 different filters tracing emission from oxygen (blue), hydrogen (green), and sulphur (red). The color is also representative of the temperature in the ionized gas: blue is relatively hot and red is cooler. The Carina Nebula is a good example of how very massive stars rip apart the molecular clouds that give birth to them. The bright star near the center of the image is Eta Carinae, which is one of the most massive and luminous stars known. This picture is a composite of several exposures made with the Curtis-Schmidt telescope at the Cerro Tololo Interamerican Observatory.

Oxygen is giving the blue colour which means my DSLR camera is not lying.
It's true however that a DSLR doesn't have good quantum efficency at Ha .
It's also true that blue should be there in your data.

Don't get me wrong.
You have taken a fabulous picture - that I could only dream of taking.

[Martin Pugh]

Superb result Peter. Really quite excellent.

but c'mon mate...post your exposure details!

cheers
Martin

[Peter Ward]

Originally Posted by alpal

Hi Peter,
David Malin's images seem to be all red too.

What about this image?

http://www.wolaver.org/Space/carinanebula.jpg

http://www.wolaver.org/Space/carinanebula.htm


Oxygen is giving the blue colour which means my DSLR camera is not lying.
It's true however that a DSLR doesn't have good quantum efficency at Ha .
It's also true that blue should be there in your data.

Don't get me wrong.
You have taken a fabulous picture - that I could only dream of taking.

You're suggesting David Malin's images are too red??

... sorry the AAT team went to some lengths to ensure the calibration of their (emission line) data.

Your links are to SII, Ha, OIII...ie false colour images, it make no sense to compare that to a RGB image.

Yes, there is indeed H-beta (magenta) and OIII (cyan) at the core of the nebula, and this should give it salmon/magenta colour.... but "DSLR" blue it simply isn't...

That's plain and simple a limitation of DSLR and non-daylight light sources.

Helmholtz colour theory covers this pretty well.

[Bassnut (Fred)]

Well thats pretty impressive I must say. A tad monochromatic perhaps, more blue would be nice .

Soo, how would you say the RHA stacks up against a pure RC, optically?.

[Peter Ward]

Originally Posted by Martin Pugh

Superb result Peter. Really quite excellent.

but c'mon mate...post your exposure details!

cheers
Martin

Thanks Martin.

Give you a hint ... one hour per panel....

[Peter Ward]

Originally Posted by Bassnut

more blue would be nice .

Arrrrrggh!

Originally Posted by Bassnut

Soo, how would you say the RHA stacks up against a pure RC, optically?.

Thanks Fred. For starters they are awful to look though, big secondary that throws shadows from all but the shortest of eyepieces. It's a wide field astrograph and not much else.

Optically, the RC eats it for narrow field....much better res provided the seeing is OK (my RCOS is down at the moment...mirrors are out for a re-coat)

But in terms of field flatness and zero abberations across a 70mm field... the RHA is a good as it gets. I'd like to see a built in orthogonality adjuster, but otherwise it oozes quality that AP is famous for.

Edge stars are little needles (in fact I use the guide chip to focus!) and when they aren't, I know I haven't put the camera in place correctly.

[alpal]

Peter,

Helmholtz colour theory covers this pretty well.

I haven't heard of that.
I'll have to google it.

Would you please be able to publish some small pics
of separate RGB frames for your Eta Carinae?
I would especially like to see a blue frame.