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 (http://www.atscope.com.au/BRO/gallery140.html)

[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]

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.



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]

wow love it:eyepop::thumbsup: 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:question: ship loads any way. So many!
Focusing system: hairy eyeball and steady right hand.:lol:
Processor by Intel.:lol:
Redback Beer by Matilda Bay....:lol:
Great image.

[Peter Ward]

Thanks Steve,

I've now uploaded the complete mosaic. Same Link as before
(http://www.atscope.com.au/BRO/gallery140.html)
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 :rolleyes:

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

[multiweb]

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

[Octane]

Oh, my.

That is simply incredible, Peter. Wow!

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

Just sensational.

H

[Peter Ward]

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



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

[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.

Look at the blue in my pic:

http://i262.photobucket.com/albums/ii119/alpal2002/EtaCarinae5frames_DSS_PS_PS_PS_21.j pg

[Moon]

Love it!

[Peter Ward]

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!:eyepop:

Will be great to see it finished. Well done!:thumbsup:

[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.

[Martin Pugh]

Superb result Peter. Really quite excellent.

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

cheers
Martin

[Peter Ward]

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

... 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]

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]

Thanks Martin.

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

[Peter Ward]

Arrrrrggh! :lol:


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.:thumbsup:

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,


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.

[Ross G]

That is one amazing photo Peter.

Thanks.

Ross.

[Peter Ward]

OK...I've done better than that.

This is a link (http://www.atscope.com.au/BRO/gallery141.html) to a mouse-over of the blue versus H-alpha channel data, complete with spelling errors :)

As you will see H-alpha (a very deep, but visible red which DSLR's are quite insenstive to) dominates, with many features simply not emitting in blue at all.

Cheers

[Peter Ward]

Glad you like it Ross :thumbsup:

[marc4darkskies]

Really nice Peter! :thumbsup: Agree with your pinkness comment though - the outer regions should be redder IMO.



PROVE IT!!! :) BTW, I'm coming down to your place just so I can see it at full res - this weekend OK? ;)

[Peter Ward]

Working on the pink bits...:)

I'll be in Hong Kong. Seriously. (Hummm.. Canon Macro lens....)

O.K. just for you Marcus....Here is a crop at 100% res from the extreme field edge of the top left pane.

http://www.atscope.com.au/BRO/gallery142.html

[alpal]

Peter,



Thanks for that Peter,
I can see that the blue is no where near as strong as the red.
It would be interesting to see a different processing with
equal RGB colour graphs using curves in Photoshop -
in other words artifically balanced.

[marc4darkskies]

See, that wasn't so hard was it? :lol: (Thanks! :thumbsup:)

BTW, I'm bringing the family with me on the weekend too! Just leave the key under the mat! :D

To be honest I'd say it's not better than an APO but mate, as good as!! :eyepop: Remembering it's from the corner of the frame too - it's amazing!

[LightningNZ]

The fine, pin-point stars really make it. Those are some truly superb optics.

Thanks for sharing,
Cam

[Peter Ward]

You are welcome



Only as good as a 12" F3.8 APO???..... I can live with that :lol:

[Paul Haese]

Oh I do like the field of view and the star sizes are sublime. Like pinpoints. Not keen on the main nebula though. Lacks punch to me, but each to their own.

Now show me somthing like that NGC3576 finished. Please. :)

[Peter Ward]

Appreciate your frank comments Paul.:thumbsup:

If by punch you mean: some sort of sharpening... decided to keep it "au naturel ". As you say, dealers choice. But I might fiddle at the edges at tad.

I wont bore interested viewers by heralding the changes, they'll just happen from time to time.

Another object!? What? move away from the program?? :lol:

Yes, I think it's time to move on. 3576 I've decided looks poor in wide field NB. RGB seems to be the go ;)

As for when...Did I mention the forecast again today??? :rolleyes:

:rain::rain::rain::rain:

[TrevorW]

very tidy image, tight stars although core seems overly bright and not as detailed as I've seen in some images, colour also bit pale IMO

overall though not bad

[Stevec35]

Pretty good Peter. I like it a lot.

Cheers

Steve

[Stevec35]

Hi to All


Recently I entered an informal partnership with Dean Salman who has a remotely operated observatory with a 20cm F4 Maksutov Newtonian about 50 miles from Tucson Arizona. Dean is going to allow me to use the observatory about 2-3 times a week and in return I am to provide him with some data on selected southern objects. Dean’s main speciality is the Sharpless catalog and he has a web site of his Sharpless images here:

http://www.sharplesscatalog.com/

I’ve been taking some images for a few nights now and here are the preliminary results. The camera is a QSI 583 WSG. All the images are black and white at the moment but some colour should follow soon.

M101. This has always been one of my favourite galaxies. The image is a 60 minute luminance shot taken under fairly bright moonlight.

http://members.pcug.org.au/~stevec/M101_DSl.jpg (http://members.pcug.org.au/%7Estevec/M101_DSl.jpg)

IC405 in Auriga is also known as the “flaming star” nebula. This is 2 hours of hydrogen alpha:

http://members.pcug.org.au/~stevec/IC405_DS.jpg (http://members.pcug.org.au/%7Estevec/IC405_DS.jpg)

PuWe1 is an incredibly faint and large planetary nebula in Lynx only discovered in 1980. It has a diameter of about 20’. This image is 5 hours 20 minutes Hydrogen Alpha.

http://members.pcug.org.au/~stevec/PuWe1_DSt.jpg (http://members.pcug.org.au/%7Estevec/PuWe1_DSt.jpg)

Cheers

Steve

[Stevec35]

Sorry - please disregard the previous post. It should have been a new thread. A senior moment I think.

Steve

[Peter Ward]

Thanks one and all for you input.

As a thank you I've uploaded a desktop sized version (well, the same size as my 24" LCD desktop). Also works on ipads.

Got to this link for a free HD version of the image!
(http://www.atscope.com.au/BRO/gallery143.html)



No worries. Get those too eh? :)



Happy to supply some eye candy



Thanks... The image is slowly evolving via valued input such as yours :thumbsup:

[alpal]

Hi Peter,
I hope you don't mind ?
I took a small crop of your photo &
adjusted it to give more blue & less red.
It's only a tiny jpg.
What do you think?
I like the effect of the different coloured areas.

[troypiggo]

Peter, that's absolutely exquisite. Top shelf stuff.

[Peter Ward]

Here's a link to an albeit tiny version of the same field by David Malin
http://www.aao.gov.au/images/captions/uks006a.html

If being pink makes you happy, then so be it. :)

Accurate? I'll go with David's rendition.

[Peter Ward]

Thanks

[Octane]

alpal,

There's a reason why people get their DSLRs modified -- to give them a similar spectral response as monochrome CCDs. You need to stop worrying about what your camera shows you in the blue channel (oxygen emission). DSLRs are designed as primarily terrestrial imaging devices. Astrophotographic CCDs are designed to capture as much of the spectrum as possible. What you're seeing is scientific but, with a big splash of subjective creativity.

Once you get over the hurdle of not seeing what you see in /your/ images, you'll want to get your camera modified, or buy a CCD that isn't limited by an IR/UV blocker filter.

H

[alpal]

Peter,


Actually it's going blue.

I have been affected by watching Ken Crawford's videos
on digging out the details.

First of all I thought it was cheating but then I thought -
why not do it with colour too?
If there is a colour information that allows you to see detail that
would otherwise be invisible - then accentuate it!
It's really a matter of taste & trying to get the most out of data.

David's rendition is your taste & is of course more accurate.

It's all good fun - anyway!

[alpal]

Don't worry ,
I'm researching cameras every day.
I just can't decide which one to buy.
I will however go it alone on processing if need be.
I like to dig out colour detail.

[Peter Ward]

As you should! :)

I've made a few tweaks... including a just tad more blue ;)

[alpal]

That's much better & a larger picture too!
I can make out different detail now.

[Peter.M]

If realism is what your looking for Alpal, Hydrogen typically ionises between 5000 and 10000 kelvin. So if we were out in space and could view it with our own eyes I can assure you we would be vaporised, along with any DSLR we took with us. ;)

[alpal]

Sure - but the DSLR camera is made to match the human eye
so that the pictures of say people's faces look real.
If the DSLR says there is blue there -
then blue is there.
Anyway - great job - your optics are perfect - you'd
have to be very proud of that last pic.
The FOV is huge & I could only dream of doing that.

[Peter.M]

The DSLR is made to match the human eye on earth, and unfortunately a sensor does not discriminate between NIR and visible photons. Anything with a temperature will emit black body radiation in the NIR and this is what the cameras filter is there to block (otherwise our photos would all look like they were taken from a COPS helicoptor), unfortunately the filter does not stop sharply where NIR becomes visible, and this causes low QE for the longer wavelegnths.

The human eye percieves red and blue relatively poorly as shown here.

http://en.wikipedia.org/wiki/File:Eyesensitivity.png

[TrevorW]

Nice tweaking Peter, there appears to be better definition in the core and little more colour depth but I'm now viewing this on my home monitor

[alpal]

That just proves that if there is plenty of blue
& red in the DSLR histogram then those colours are
in reality actually quite bright.
In fact even brighter as the Bayer Matrix has 2 greens for every red or blue pixel.


I think the processing theory is correct if a DSLR palette is used
& enhanced for the dynamic range of all colours to dig out
that little bit more detail than the eye can see.
Also you can get a situation where if the Ha narrowband is used for
luminance then the colours end up all wrong.

Certainly if we look at the Hubble Palette the 3 colour narrow band photo
is being deliberately used to give that detail that would otherwise be unseen.

In the same way microwave radio pictures can be built up with colour.

[troypiggo]

Sounds like you're confusing what part of the spectrum of light is hitting the sensor vs what is displayed on screen here. With Hubble palette, 2 of the 3 color channels are from red spectrum light. To represent those 2 reds on screen we put them in the R and G channel of the final image.

As H said, you need to change your thinking. Separate what the sensor is receiving from what the image displays.

[Peter.M]

You are assuming that you are correct about DSLR being the same as a human eye, and then using that assumption to prove your own point. That logic is a fundamental mistake when evaluating any scientific hypothesis.

The human eyes insensitivity to red and blue can be proven when visually looking at these nebula as they apear greyscale ( I know due to rods). What this dosent prove is that an exposure with a DSLR with more blue than red saturation is a linear representation of the concentration of blue light hitting the camera from that object. Because some of the red is blocked by the IR filter.

I will leave it at this, because I feel like I am hijacking Petes thread. This is a beautiful representation of the object regardless of what colour people think it should be.

[marc4darkskies]

Now you're talking Peter!! Very nice! :thumbsup:

[Paul Haese]

No not sharpening it was probably more to do with contrast in the original image. I guess I really like high contrast images, but that as you know has to be balanced against the dreaminess (er gaseous nature) of the nebulosity. Your latest version certainly has a lot more contrast in the surrounding nebula and out skirts (especially like the top left of the image which is lovely), but the key hole looks washed out or flat a little to me.

Yeah I hear you about weather. Our turn now. :rofl:Must have been something I said. :) Serves me right.:thumbsup:

[cventer]

Wow Peter just lovely. Just catching up on this with color added. That STX16803 and scope are a winner of a combination. And o course the processing is excellent as well.

I just put an offer on an unsused STX16803 on Astromart but the seller wont bite. Only wants to ship inside USA :-(

[gregbradley]

Perhaps the most exquisite stars I recall seeing in an astrophotograph.
For that alone the scope was worth the price.

Overall a fabulous image. Flawless.

Greg.

[Peter Ward]

Thanks Greg. Very kind. Went with a totally different layered masking technique to blend the Halpha. Seems to have worked :)



They are a superb camera with the RHA, as the off axis Guide stars are pristine dots and very easy to guide on even in SII.



:lol: yep for me weather and work.... Now north of the equator for a bit.
Re: the keyhole, as one David Malin puts it, "respect the light". Unfortunately doing so means it will be bright and lacking contrast... Which is not to say I can't mask it off for a disrespectful version :)



Thanks Marcus. I think I'm bumbling along to a version I'll finally be happy with :)

[cventer]

Peter dont hold out on us. This is allways a real challenge. Love to hear about how you went about the Ha blend.

[Peter Ward]

It's complex..and not easily described on IIS.... but I'm giving it some serious thought and will probably do a write-up when I've got a bit more spare time.

BTW after an absence of a few days, I've uploaded the latest smaller (33%) but higher quality .jpg revision (http://www.atscope.com.au/BRO/gallery140.html) as the prior Las Vegas versions were probably a bit over the top :)

[alpal]

That's great detail Peter.
I had a go at adjusting it -
I hope you don't mind?
see here:
http://i262.photobucket.com/albums/ii119/alpal2002/CarinaBigweb_18thMarch2012_d.jpg