Ngc6188

[Slawomir (Suavi)]

Due to uncooperative weather I decided to utilise t12 telescope from iTelesope.Net to collect data for a wider filed around NGC6188.

Camera: SBIG STL-11000M
Optics: 106mm F5 refractor

Here is the result of combining 1.5hr of data through Halpha filter: http://www.astrobin.com/full/177429/0/

I was rather disappointed with the quality of data, in particular the stars are sub-standard.

Here is another image of the same DSO, but representing a narrower field, taken about a month ago with my modest gear. Acquisition was also 1.5hr: http://www.astrobin.com/full/171726/0/

Although an interesting experiment, collecting data remotely with some else's telescope did not seem to provide with the same satisfaction as tweaking with own scope.

I think for now I will stick to my own gear and will just need to wait for better weather on the weekends.

[gregbradley]

A rather graphic demonstration of the higher QE of the Sony sensor compared to the Kodak KAI11002.

Not sure what you mean about the stars on the FSQ image. They look good to me. Overall though I do prefer the widerfield of the FSQ image.

FSQ/STL11 is a super combo. I used one for a while. They seem to match each other well. But yeah its going to take longer to get the same signal to noise ratio as your Sony chipped QSI which has around 66% QE in Ha versus about 30% for the STL11.

Greg.

[Eden (Brett)]

Bit hard to tell what the stars are like from that cropped/resized image, but if there's clearly a problem which could be due to either tracking or the telescope optics, open a support ticket. I did a couple of hours on iTelescope a few weeks back and ended up with very eggy stars in all of my exposures. After I reported it, they promptly refunded my points

[Slawomir (Suavi)]

Greg, Astrobin seems to reduce resolution of jpg images -I can clearly see elongated stars in the subs - if it was from my own set-up I would be crying.

It is not due to quality of the camera or the scope (both are excellent I would love having them at home), but possibly flex, CCD tilt and who knows what else.

I used a few of their other scopes out of curiosity and some are better than the others. Nevertheless, I like experimenting and iTelescope.Net gives an opportunity to remotely use various set-ups that I will probably never be able to afford.

[Slawomir (Suavi)]

Originally Posted by Eden

Bit hard to tell what the stars are like from that cropped/resized image, but if there's clearly a problem which could be due to either tracking or the telescope optics, open a support ticket. I did a couple of hours on iTelescope a few weeks back and ended up with very eggy stars in all of my exposures. After I reported it, they promptly refunded my points

Thank you for the hint Eden.

[RobF (Rob)]

Its also pleasing in a way to see that such expensive gear is in no way immune to the rigours of flex and tight guiding, as you say. I don't mean to put down iTelescopes, but rather "celebrate" the fact that this is a challenging pursuit.

Slawomir, the only difference I can see in the stars is more "bloat" on the FSQ/11000 image (but man that is a glorious FOV!). Presumably more time to get the faint neb showing due to QE issues Greg has mentioned, and over that time the stars bloat a little? Perhaps some strategic masking/erosion in PI required?

I wonder if the clouds are going to tease us this weekend - looks like sucker holes likely tonight.

[multiweb (Marc)]

I see what you're saying about the FSQ fov. Top looks smeared. Maybe field rotation. Your gear gave a much superior rendition. I suspect a better image scale helped as well.

[Rod771 (Rod)]

Originally Posted by Slawomir

Greg, Astrobin seems to reduce resolution of jpg images

To view the full res image on Astrobin just click the button in the top right hand corner (see attached image). Or when sharing a hyperlink, copy/paste the Astronbin link address titled "Real" http://astrob.in/full/177429/0/?real=&mod=None this will load the image in full res.

Nice image Slawomir!

[Slawomir (Suavi)]

Rob- I see it the same way regarding the rig and how you use it, and it is also quite encouraging to be getting similar or perhaps in some ways better results with own gear and through persistence and exploration

Marc- yes, the FOV is awesome. Image scale surely played its role as well.

Thank you Rod- yes, I was aware of this icon, but I still suspect that Astrobin compresses jpgs even in the 'original' full resolution.

[gregbradley]

It is not due to quality of the camera or the scope (both are excellent I would love having them at home), but possibly flex, CCD tilt and who knows what else.


I looked at the large file. Yes some egginess but not bad. A bit of tilt as you say in the bottom left. Welcome to full frame sized sensor imaging. Everything is a lot harder than with smaller chips.

Greg.

[RickS (Rick)]

Slawomir,

The image you captured is very nice. The t12 image is a bit ordinary and I wouldn't be happy with it either.

Astrobin does strip ICC Profiles from images which I find very objectionable. I hadn't noticed other issues with image quality before but perhaps I haven't looked hard enough?

Cheers,
Rick.

[Paul Haese]

There are some definite issues. Certainly tilt and I think either guide parameters or PA might be slightly off. This scope has a fully corrected field that more than covers this sensor so it is not the scope.

I have seen images from another of their scopes there and I saw similar aberrations but to varying degrees. Then again, some here think I am fussy.

I am sure if you identify what you think is wrong they will help you out with more time.

[Slawomir (Suavi)]

Thank you Rick - you always encourage others by positive feedback and by demonstrating how processing should be done

Actually now I think that Astrobin (or any image by the matter of fact) displays a bit differently on my tablet. When I saved the image from Astrobin in full resolution it had about the same size as the original file.

Thank you Paul - I have contacted the guys at iTelescope.Net.

Attached is a crop from the sharpest sub (not from a corner of the sub). I think I can consider myself being fussy too...

[RickS (Rick)]

Nothing wrong with being fussy. That's the path to improvement in this game