It's keyhole season

[Peter Ward]

This is a 1:1 crop of a much larger field....and despite it's constant re-visiting this region has much to offer.

http://www.atscope.com.au/BRO/gallery17.html

Details 20:10:10 RGB STL11k, AOL, RC14

Cheers
Peter

[renormalised]

Can we shoot 'em, and what are the bag limits??:P:D

Excellent piccie, Peter. Great detail and colour, with nice, round stars:)

[iceman]

Nice resolution!

[jase]

Great work Peter, certainly for a straight RGB composition.

[strongmanmike]

Nice colours Peter :thumbsup:

The resolution isn't quite what I would have expected with the kit you used but I guess the SBIG AO unit is actually not for combating seeing, as per the pro units on big telescopes but rather just highly accurate autoguiding, is this correct?

Mike

[Peter Ward]

Thanks for the feedback.

Mike's comments regarding the resolution is interesting. No USM or sharpening has been applied, so the image certainly has a soft/smooth look (intentional)...that said the star sizes are typically about 30% smaller than say my 6" AP.

If you look closely at a small triple star group located at 3.00 o'clock in the right dark lobe of the keyhole they are cleanly resolved and well sampled, despite the pretty average seeing I get atop a ridge-line.

True, amateur AO's do not compensate for wave front seeing. But they do correct isoplanic (tip-tilt) errors very well.

That said, once you have tracking focus etc nailed, IMHO seeing dominates image resolution much more than say, instrument aperture.

An additional H-Alpha L+R layer would no doubt give the image more "snap" (eg. smaller stars, more nebula contrast) but I'm still mulling over whether this buggers up the colour too much.... and looking out the window makes me think an H-Alpha layer won't be coming anytime soon.

Damm this Sydney weather! :)

[rogerg]

Nice shot Peter. What I'd really like to see in this area of the sky though is a shot where the lobes of Eta are correctly exposed. It looks like you have the resolution and magnification there to get some detail in them? :)

I sympathise with clouds, it has been 2 or so weeks of cloud and rain here. Weather too dodgy to leave things running.

[Peter Ward]

Not quite sure what you mean by "correctly exposed" Rog....err something like
this? http://www.atscope.com.au/BRO/images/nb/keyvhr.jpg

(same data, different processing)

Cheers
Peter

[Ric]

Beautiful looking closeup image Peter, the fickle finger is showing up quite nicely as well.

Cheers

[rogerg]

No, sorry, let me try to better explain... by Eta I was meaning the star its self. I notice in this (perfectly exposed) shot that this thread is regarding Eta (the star) looks non-circular, like the lobes are there, but "burnt out" by the longer exposures to get the nebulosity of the Keyhole. What I'd be interested in seeing is a shot that shows the actual lobes on the Eta star, like (but obviously not hubble quality): http://hubblesite.org/newscenter/archive/releases/1996/23

Hopefully that better explains.

Edit: I might not be correct that it's Eta the star visible in your shot here but I think it is... but that's largely irrelevant anyhow, just made me think of the idea again.

Roger.

[Peter Ward]

Ah...yes...I'm understanding now. Yes, It would be possible with a very brief exposure to get some structure around Eta itself. Might have to look at that...but it would be a challenge to layer in, due its intrinsic brightness.

Cheers
Peter

[rogerg]

Yeap, something I haven't even tried with my NABG camera :)

[Peter Ward]

Rogers feedback promptem me to think...how would the data go re-sampled?

http://www.atscope.com.au/BRO/gallery18.html

is the result.... res not too shabby?

Cheers
Peter

[PhotonCollector]

Hi Peter

Gee when I saw your image of the keyhole I thought it was an old image I did with my 12" GSO scope and my modded Canon 300D DSLR - no adaptive optics or anything though. This is the image I am referring to http://www.skylab.com.au/pmsa/KeyHole.html

It is also a 1:1 crop with some unsharp masking - maybe a little too much in retrospect and the sub-frames must have been too long as the stars are burned out too much - but nevertheless similar to your own image.

clear skies

[strongmanmike]

It's a bit like when you keep putting smaller and smaller FL eyepieces in your scope, while the image gets closer and closer the image never the less deteriorates. Sure the image scale increases but the asthetic view, particularly percieved sharpness and brightness, through the eyepiece never the less decreases. There is a point of deminishing returns and one settles for the right eyepiece to give the best view taking into account seeing and image brightness.

Don't get me wrong Peter this is a lovely image in many ways but its over all look is one of too close is too close and it doesn't quite work for me..not that this really matters though only a trivial discusion really and I do like your image none the less, even if for no other reason than for its great image scale :thumbsup:

A great example of where it "is" working for me is in Eddie Trimarchi''s image from a few years back done with his C11 at long FL with an AO7 and utilising more planetary imaging like techneques, and yes he has even detailed the homunculous around Eta :eyepop: This is for me pound for pound one of the best amateur deep sky images around, very inovative and technically advanced for its day.

http://astroshed.com/st10pics/eta.jpg

Mike

[strongmanmike]

This image ilustrates exactly what I was talking about, Paul has chosen the right eyepiece for his telescope (so to speak) and the resulting view is very asthetic.

Great shot Paul :thumbsup:

Mike

[Peter Ward]

Indeed, Eddies shot is a corker. I think he was running at a FL of about 5 metres and used a slick layering technique to preserve details within Eta itself...I've long admired that image.

USMasking/Sharpening image data does make it difficult to preserve the star sizes/natural look and retain their colours. At the end of the day the line between art and science can get pretty blurry :)

[renormalised]

Peter, I think what Roger is looking for is a shot of the Homunculus itself. You'll have to compensate for the glare of eta itself, if you try.

Have a go and see what you can get.