The Dark Tower

[gregbradley]

This one was taken on Friday night which is the night which had the better seeing of the 2 nights. Stars were only slightly twinkling down low
on the horizon.

Another fabulous southern object. Not too many examples of this one on the net. It is a cometary globule.

Tak BRC 250, Apogee U16 camera, Baader filters.

LRGB 110 30 30 30.

http://upload.pbase.com/image/116185769 widefield


http://upload.pbase.com/gregbradley/image/116208599 crop

Here's a photo of the setup:

http://www.pbase.com/gregbradley/image/116209412/large

I prefer the crop myself.


Greg.

[renormalised]

Excellent shot, Greg:D

The stars are pinpoint to a tea....and there's so much emission neb' in the area that you've picked up. I really like the way it frames the dark neb' there, it's a great contrast:D:D

I like the crop too, but the wide field view puts the tower in its context:)

[gregbradley]

Thanks Carl.

I had some trouble with the processing as the red histogram is massive compared to the green and blue. Earlier versions were too red so I hope I got it balanced.

Greg.

[marc4darkskies]

Very nice indeed Greg! :thumbsup::thumbsup: Like the colour. Have you thought about toning down the star brilliance a bit (curves / star size reduction) to highlight the the neb better?

Cheers, Marcus

Edit: Reduced star billiance EG attached (quick & dirty) ...

[Alchemy]

not too bad at all, brighter in the nebulosity than what ive seen previously(only seen a couple). 3 images in as many days, where do you find the clear skies ? . Not here thats for sure !!!!!!

[gregbradley]

Thanks Marcus. Good advice. I reduced the stars as much as I could and reduced a bit of red oversaturation in some stars. It does highlight the neb more. Star reduction is tricky work and easily overdone as it leaves artifacts pretty easily but they did reduce a bit.





The BRC is 250mm aperture and F5 so it gets a bright image pretty quickly which is one of the main reasons I chose it. With winter nights being 9 hours long - 7pm to 6am at the moment you can get 2 or 3 images done if they are in the right position in the sky.

[Bassnut]

Sweet Greg, very sharp and a huge dynamic range. Unusual view too, nice change.

[gregbradley]

Thanks Fred. I have wanted to image this for a while but wasn't sure how it would turn out as I thought it was only dust but it has emission nebula there as well.

[BerrieK]

Such sharp stars, and oh boy there are so many of them. I really like the colour. I prefer the widefield myself.

Kerrie

[strongmanmike]

I much prefer the wide field Greg and it is here that the BRC shines. The star images produced by the BRC just don't hold up under enlargement. The scope it is designed for big film sheets or big chips. The thick diffraction spikes, square stars and reflection halos around brighter stars are just too over powering in my opinion if you try and crop and enlarge.

Nice job, making the stars les massive would be good although I don't like what Marcus did to it :scared: sorry Marcus :hi:

The set-up is to die for too

Mike

[gregbradley]

Thanks Kerrie. I had to control the red as there was so much of it that it tended to be very red biased easily.

[gregbradley]

Hi Mike,

Yes I think you are right. This is the big edge refractors have or larger aperture mirrored scopes. Getting the stars right. The BRC is very practical at F5 getting a bright image quickly and its quite compact and stays out of the wind. Handy when imaging out in the field when you travel you need to get that image before clouds or heavy wind starts up.

I picked up a Paramount ME recently but that is for a new observatory yet to be built once I move in Nov. The NJP stays at the dark site though.

Greg.

[multiweb]

Another corker. :thumbsup: I'm just amazed how well the stars are resolved. There are bigger ones, medium sizes but still all the tiny ones in the gaps are there - pinpoint. Top shot again. :thumbsup:

[gregbradley]

Thanks Marc.
One of the specs for the BRC is star size on axis is as low as 2 microns in size which is extremely low for any scope.

[DavidU]

Monster shot ! Very tight. I love it

[Paul Haese]

Very nice image Greg. Lovely the composition in the wide field view but also really like the cropped version. Superb work.

[strongmanmike]

Yes I'm well aware of the attraction of a fast corrected telescope!!!!! ASA? :mad2:....where? :lol:

You got a PME huh? :eyepop:and a new observatory is coming...of course you need two observatories, of course :rolleyes:.. way to go, I can only imagine what Mr Telescopes will get to put on that PME :cool:

[gregbradley]

I have 2 observatories now but I never use my home backyard one as I am spoilt by pristine skies. I intend to use what I have for a while but I have my eye on a Planewave CDK 17 inch except nobody seems to post images from them which puts me off. I don't want to be a beta tester!

[Martin Pugh]

Hi Greg

I have to concur with Mike's comments. The stars just overwhelm this image, but I understand the challenge of getting them just right.

You are also right about the Planewave CDK.....tough to find images. Its outside of the mainstream telescope lines and while I have not investigated it thoroughly, I do not see a TCC comparable item to control secondary temperature, fans, and focus. I thought you sold your RC?

cheers
Martin

[Jen]

:eyepop: wow now thats a starry pic i like it Greg :thumbsup:

[gregbradley]

I'll have another go at the processing trying to tame the stars more.

Planewave has a lot going for it with what appears to be a superior
optical design. As far as a TCC goes are they that important anyway? I never had one with my 12.5 before I sold it and figured it was more for remote imagers.



Thanks Jen!

[Martin Pugh]

Without going too OT, I consider the TCC and its functions absolutely critical to acquiring the highest quality of hi-res images. By optimising both the primary and secondary mirror temps such that they were within 1 degree of ambient meant that I could image all night long, every night, without focussing in between filter changes. This took some experimenting of course i.e calibrating the secondary heater, calibrating the fans and altering the fan aggressiveness, but the output was a single focus run at evening start, then an entire nights imaging, multitple filter changes without focussing. And then there's dew...did not get any at all.

Of course, without the TCC, I presume you had used a third party focussing mechanism for the secondary, like a Robofocus.

Finally, without a TCC, you cannot use a rotator...and you know how small that guide window is on a scope that has 3m focal length.

cheers
Martin

[gregbradley]

Hi Martin,

Interesting. I used the Robofocus on the secondary that was built in. Mine was a closed tube and I didn't get dew either. I also found focus did not shift throughout the night (my dark site has fairly stable temps though where it falls for the first 3-4 hours then a slow fall from there until dawn). My BRC hasn't dewed either and temp changes don't affect focus much at all (very slight, I would refocus if I got a 3C change but usually I see only about 1-2C change).

Your images showed higher res than mine so perhaps going this extra mile paid off. With filters they tend to be slightly different focal points as well despite the marketing although I find they are very close and at this point don't make any allowance for the slight difference as it would mean sitting with the scope all night or setting up some automation software.

greg

[RB]

Greg that's a gorgeous image to be sure.
I know how hard it is to tame the stars, I wouldn't know where to begin if I were imaging this object.
The overall image is fascinating though and you've done a great job with it.

I never get tired of drooling over your setups, thanks for sharing those too and congrats on the Paramount !!

I look forward to more.

:)

[gregbradley]

Thanks Andrew.

The quest for the ideal scope is somewhat of an ongoing pursuit.
The TEC180 is close to the top, the BRC is great but as Mike points out the star shapes sometimes aren't so good. If I were game I'd get the spider changed over to something more suitable for astrophotography. ASA had the same problem with theirs and went to a double spider arrangement. S shaped spiders also don't give diffraction spikes.

The Paramount will be fun to use and a new learning curve.

Greg.