Keyhole: high res H-alpha

[Peter Ward]

I made the comment earlier that seeing is *really* important when it comes to high-res deep sky imaging.

I've pulled the colour version posted earlier at the URL below and replaced it with the new B&W version (for now ;) )

http://www.atscope.com.au/BRO/gallery37.html

The res is not too shabby and shows features I've never really noticed before: shock waves coming off Eta itself.


Cheers

[multiweb]

Beautiful shot - extremely sharp. :thumbsup:

[Garyh]

Now that is a awesome shot Peter!
Great resolution for sure :thumbsup:
I`ve noticed the last few nights the seeing has been pretty good up this way as well.
cheers

[Tom Davis]

Excellent detail!

Tom

[bloodhound31]

Peter, I'm not normally a fan of B&W, but shots like that could easily change my mind.

Good job mate.:thumbsup:

Baz.

[bluescope]

Very nice image Peter ... what bandwidth Ha filter did you use on this ?

:thumbsup:

[Peter Ward]

Many thanks Baz, Tom, Gary, Marc.

Many moons ago I spent a good deal of time developing and printing B&W and later Cibachrome prints.. B&W gives you a great appreciation of the light and shade in a scene.

Imaging in H-Alpha was virtually an impossibility for amateurs then, but with CCD's the process is quite straightforward.

I for one, hope it enjoys a renaissance. :)

[Peter Ward]

Baaders are 7nm.

[bluescope]

Thanks Peter ... I'm tossing up whether to get an Ha filter and have a thread going in equipment discussions forum which has pro and cons of different filters from different people ... gets a bit confusing.

Where do you buy the Baader 7nm from and how much ?
Having said that I imagine you get it yourself ;)

:thumbsup:

[Peter Ward]

I'm pretty happy with the contrast and lack of ghost reflections from the Baaders.

They are available from various vendors here and in the USA... priced between $375 (2" cell) to about $500 (50.8mm STL version).

You might save $50 in GST by going USA direct, but then again you might loose that in postage...

[jase]

Excellent resolution Peter. Very fine details on display of this show-piece target. What was the duration of the subs? Given this is a bright object, I'd imagine relatively short even though its through a Ha filter. The mid tones really dominate this image which I feel has suppressed the highlights too much. Personal taste, but I'd like to see a little more contrast to emphasise the exotic details. You still using log stretching? Perhaps that's the cause for the dynamic range woes? Still a real nice scene. Well done.

[Peter Ward]

I use my usual 10 minute urban subs. Processing as you say is often a matter of taste. I prefer subtle to overcooked but appreciate your candid feedback. A "snappier" version is now in place.

My usual drill is to: reduce, errant pixel clean up, then stack. I then use a two pass gamma scale in MaxIm. Final tweaking in PS. Nothing fancy but works for me. :)

[bluescope]

Yes the postage to Oz from most of the US dealers that I know of is ridiculous even on small items such as filters ... I mean ... come on what do they weigh guys.
Which Oz dealer would you recommend Peter ?

:thumbsup:

p.s. I think the new version does has more depth and the humunculus stands out better IMO.

[Peter Ward]

You're kidding... right? :)

I only have STL versions in stock.

My Astro Shop has some keen pricing.

[bluescope]

:lol: Thanks Peter :rofl:

[jase]

The snappier version is on the money. The subtle contrast tweaks have made a notable difference. Well done.

[Octane]

Peter,

That's very, very beautiful.

Are you going to add RGB or SHO to this?

Regards,
Humayun

[gregbradley]

Nice shot. But that is coma I see at the corners? Elongated stars in the corners yet round in the centre of the image.

Are you using a flattener?

Greg.

[pgc hunter]

that's a beautiful pic. Look at how well the Rude finger is defined. Interesting to note that both the homunculus and the middle finger salute appear to be a similar size, perhaps making the latter a viable target visually in larger scopes.

[Peter Ward]

Yes, the FFC was installed, but the slightly eggy edge stars are an unfortunate side effect of using AP's Barcon.

That said, I consider the stellar FWHM's to be extremely tight as the effective focal length was 5,400 mm.

[strongmanmike]

Well I have to say even at that mizerly sized image and image res you insist on displaying it does look very nice Peter :thumbsup: Lots of magical subtle detail as you say :eyepop:

Just as a comparison, I have cropped the same piece of field from my Ha image from last year to see what the difference is (taken at low altitude unfortunately so not perfect).

You have used a 14.5" RC at what?..5000mm FL? and a 7nm Ha while I used a 6" APO at 1140mm FL and a broader 13nm Ha filter. My image is only 3X10min exposure so could have used a lot more, you used 10min subs too but how many I'm not sure..?

I didn't use an AO device, I assume you did?

I have reduced my image resolution to match your small 1400 X 900 size at just 400k too for a fairer comparison

Overall the res is deffinitely better in yours but strangely in some areas it appears slightly better in mine..? :shrug:

As usual :rolleyes: I would love to see a higher res version of your image as I am sure in fuller res the difference would be more marked..?

Here's my image:

http://www.pbase.com/strongmanmike2002/image/110381932/original

You have handled Eta itself better than I, looks great :thumbsup:

The lack of halos around the brighter stars in your version is good too, I hope my new low reflection Astronomik filters that I have just installed will eliminate this?

Again excellent work (even displayed at low res)

Mike

[Peter Ward]

Thanks Mike. Yes, I have seen your excellent H-alpha Eta image before.

Agreed, downsizing (even Hubble) images can make them look like they are just average res, but I figure 1400 by a 1000 odd is big enough for public forums.....and is larger than many of the posts here on ISS.

My estimate is: the RC was delivering about 4x (in area) smaller stars than you've linked to.

Sure, the focal length and AO helped quite a bit IMHO, but the seeing on the night was pivotal.

[strongmanmike]

I guess the 7nm Ha helped shrink the stars a bit too..? If I had a PME and larger objective plus a permanent obs I'd have gone for the Astronomik 6nm set rather than the 13nm that I did but I had to weigh it all up I guess.

Your final image is sure to be excellent and it would be great to see it in fuller res....before the David Malin awards :whistle:

Mike

[AlexN]

Lovely start to what will be a ripper no doubt... I too would love to see a full res shot :) I like to swim in pretty pictures! :D

[gregbradley]

Oh, so you 2X or so your focal length? Quite a challenge.

Greg.