Antares/Rho Region HaRGB (REPRO added)

[dugnsuz]

Hello all,
Bad weather in my part of SA has kept me away from the scope for a while.
Last week, a break in the clouds allowed me to finish off a widefield Rho project started about a month ago.

This is the first big RGB project attempted without my trusty IDAS LPS-2 filter - I convinced myself that my skies were dark enough to lose the filter. Well, I was wrong! Even the small amount of light pollution and skyglow soon made themselves known on every sub, proving to be a pain in the subsequent processing. Live and learn - an email to Peter Tan secured a new LP filter.

Details...
Canon 'Astro' 40D (low ambient temperatures allowed the camera to get down to an average of -20ºC across the session)
Canon 70-200mm f4L IS lens @ 70mm/f4
iso1600

Image is a combination of...
71x5min subs (355 mins)
22x7.5min subs (165 mins)
3x10min subs (30 mins)

Ha (using Astronomik 12nm Ha EOS clip filter)
16x15min subs (240 mins)

No darks or flats used (naughty, naughty!)

Aligned/Combined with Nebulosity (Mac)
All processing in Photoshop CS4

High Res link...
http://s327.photobucket.com/albums/k461/doug-robertson/?action=view&current=21c.jpg

I expected a bit more oomph given the amount of data acquired, but I think the light pollution really washed out the contrast between the object and background sky - hope the new LP filter will help in this regard.

Cheers for looking, all comments welcome.

Doug:thumbsup:

[renormalised]

Nice shot, Doug:)

The one posted to here is full of jpeg compression artifacts, which ruins the piccie, but your hires shot is ace:)

Nice colours....I think the LP filter is going to do good.

[dugnsuz]

Cheers Carl...posted another lo res version above - a tad better than the first go hopefully.
Doug:thumbsup:

[midnight]

This has been a project Doug and the results are showing.

For a presentation without darks shows the capability of the camera and it can only get better from here.

I really like it - Great project Doug!!

I noticed you're using the lense at wide open. To me this is more visually appealling than the diffraction spikes from the lense iris. Are you happy with the performance at F4 (wide open)? The results seem to support using wide open in this case and pickup the benefit of round stars.

Darrin...

[dugnsuz]

Thanks Darrin - I've recently been experimenting with stopping down the lenses with aperture masks in the form of step adapter rings. Can't say that I've noticed dramatic differences from the lenses wide open apart from the increase in exposure time needed to get a bright image at the sensor. So I've given up on that and have gone back to using them wide open... f4 for the 70-200 and f5.6 for the 400mm - that's as slow as I want to go. And as you've stated I too am not a big fan of the lens diffraction spikes.

Re Darks: in this instance I found that calibration of the subs with a temp matched library dark introduced aberrations rather than removing them!
I find that I'm not as precious about all the calibration stuff on some images - probably more laziness than anything else - sometimes it works, sometimes it doesn't!! I think I'll explore the "Bad Pixel" algorithm in Nebulosity to deal with hot sensor pixels.

Did you buy Paul's Astro 40D?

Doug:thumbsup:

[dugnsuz]

Cheers Steve - by the time the skies clear Antares will probably be close to the zenith in the early evening!!But the moon will be back too!:(
And, this region is certainly not the most exciting Ha object...:P Much nicer in colour!
Doug

[midnight]

Yep!!

And I am keen to give it a good run - but the West's version of El Nino has arrived and it has pretty much stalled my imaging opportunities.

I was actually going to modify my existing 40D. I have the Baader filter and I was going to try the cooler box method to start with (bought a peltier from Jaycar) but suddenly Paul offered his 40D and I couldn't resist.

I want to stay on DSLR for at least another year as I am learning at a pace that I'm happy with. Starting to get information and ideas overload at the moment.

I am actually going to experiment with Paul's 40D for say long exposure (eg 10min) and my existing 40D for short exposure at the same time to get the proper exposure layering so I reduces my physical time on the target.

Cheers,
Darrin...

[dugnsuz]

Glad it's gone to a good home - my mate Craig_L was considering it but you just pipped him to it. I'm certain you'll love the results - you already know how easy to use the 40D is for astro work.
I heartily endorse pushing past the 10min sub barrier with this camera!!
The cooled DSLR and your 200mm f2.8L will be a killer combo.
It's great to be free of those 'in camera darks' too!
Looking forward to another Astro 40D owners posts...

Cheers
Doug:thumbsup:

[rcheshire]

Nice one Doug. Those long plumes are wonderful. Long sessions, but necessary in the burbs with a DSLR. I like the round stars too, but find that they become too bloated with aperture wide open. At f/3.2 the 200mm goes spiky, but there is more control over bloat. And, to get proper exposures with the sodium filter 5 minutes or more is necessary, preferably 6 to 7 minutes.

Maybe an O ring behind the rear lens would reduce the spikiness of the Iris. It's a thought.

[dugnsuz]

Hi Rowland - I have used the cheap step filter rings that you can pick up on ebay as lens aperture masks to stop the down the lens and avoid the spikes. They work but increase the exposure time needed...
http://www.ebay.com.au/itm/77mm-58mm-77-58-Step-down-Filter-Ring-Adapter-/220589359566?pt=AU_Cameras_Photogra phic_Accessories&hash=item335c2681ce

I think they would be beneficial for a f2.8 lens to minimize the star bloat - stopping down f4 and f5.6 lenses is a recipe for sloth-llke performance!
Doug:thumbsup:

[Paul Haese]

Nice going Doug. This looks pretty punchy overall to me. Colour saturation is pretty good too. Maybe do several repro's and see where this takes you.

[DavidU]

Mighty image Doug. I love the colours.

[Craig_L]

Very nice Doug. Nice composition as well. Reminds me of a firework's display. Wish I had bought Paul's cooled 40D. Craig

[dugnsuz]

Thanks Paul - constantly tweaking! Although I think I'd like to have another go with an IDAS LP filter in the mix to see if there's a big difference in contrast.



Bit Fruity eh David!!LOL


Cheers Craig - just have to hang out for that FLI instead!!

Doug:thumbsup:

[h0ughy]

very punchy and i like the framing. colour is saturated but in a nice way and is very pleasing to the eye. As Paul said have a few repros ;)

[Lester]

Very nice image Doug.

[dugnsuz]

Thanks David - I may pull back on the saturation a tad - you can almost taste those colours!!:lol: Fruit Salad anyone!?


Cheers Lester:thumbsup:

[dugnsuz]

Louie Atalas suggested that a more aggresive stretching of this image might make it pop a little more.
Gave it a go...

http://s327.photobucket.com/albums/k461/doug-robertson/?action=view&current=21d.jpg

Cheers
Doug:thumbsup: