Ray
Roboscopes Guinea Pig
Ray
Roboscopes Guinea Pig
Ray
Roboscopes Guinea Pig
This is my attempt at Thor's Helmet (NGC 2359). Ha and O3 only. Job 1205.
I am not going to make too many claims for it. The O3 filter was creating a lot of star haloes, and somewhere in the processing, these seem to have become square. I also had quite a bit of noise in the fainter nebulosity, and I ended up clipping the background to get a reasonable image. You could also argue that the whole thing has been over-smoothed, but viewing the image at a sensible distance, this is the best of a number of versions for showing the nebula clearly.
Ray,
Another attempt at Thor's Helmet. Much more gentle processing and a lot less evidence of brutal overprocessing.
Thanks for your suggestions on dealing with star haloes. My big problem was the bright star with the massive halo centre bottom third. Starnet does not remove all the stars, especially those with big haloes. So I took the starless version from PixInsight into Affinity Photo. Burned the halo down to a more reasonable level (but not removing it, 'cos that looks weird), and then imported back into PixInsight combined with the star_mask and finished it off.
I think that is better. Do you agree?
Hi Richard,
Just wondering if you have Starnet2 installed. I've tried both versions out and for me the halo is placed into the Starless image using the new version, and in the original in the Starmask. Can you confirm which version of Starnet you have, and if it's version 2 can you confirm that the halo is in the Starless image. From there it is quite easy to deal with. Please let me know at your convenience.
Cheers,
Ray
Ray
Roboscopes Guinea Pig
Hi Ray,
I was using the original Starnet. I have now added Starnet 2 and it does seem to do a better job of removing the stars, but you can see from the attached the big halo is still there. This is after the usual preprocessing and combining Ha and O3 followed by star removal, but before any cleaning up.
Following the same steps of decreasing the intensity of the halo, some Curves Transformation, LHE and denoising, and then adding the stars back in, I get the second image.
Hi Richard,
Apart from that tiresome halo in a prominent position, the stars and particularly the ones in the nebulosity are far better. For me a definite improvement. Given some more data there wouldn't be the need to really stretch it so much either so's to reveal as much of the nebula as possible. I think it's probably too late to collect any more until it starts rising again. I do like that nebula.
Cheers,
Ray
Ray
Roboscopes Guinea Pig
Thanks Richard I guess I need to be more patient. I did submit it to pier 3 but it only got as far as 10 percent.
Instead of a clone brush, layers could be used with an eraser to reveal the part of the underneath layer you want. I use the clone because I find it easier to do.
Cheers and CS,
Ray
Ray
Roboscopes Guinea Pig
Ray,
Thanks for the tip on using the clone brush. I do it a different way, but I suspect it comes to the same thing. The less stretched images have lower intensity values per pixel (unless saturated). This is equivalent to lower exposure in the daylight photography world. So by cloning a halo area from a less stretched image you are taking a section of a lower intensity image and replacing or blending it into the bright halo in your fully stretched image.
I use the Burn tool in my photoprocessing app (Affinity). The name comes from using photographic paper where you would use a mask with an aperture to selectively increase exposure in areas you want to be darker when making an enlargement. The Burn tool reduces luminance in the area you are treating. So I think that is functionally equivalent to what you are doing with the clone brush. But maybe not. What do you think?
The opposite of 'burning' is 'dodging' where you would use a card disk on a wire to shade areas of the print you wanted to lighten. Interesting how the same words are used for tools when they now act in a very different way because you are not working from a negative!
Hi Richard,
Thanks for all that and the memories it brings back. Oh for those days spent in your dark room and smell of the chemicals. I'm beginning to think that maybe they're jointly responsible for my lapses of memory.
It was kind of essential back then. You'd experiment by taking several exposures on B&W film using a few different exposure times, using the standard lens for constellations and a moderate telephoto lens for the Pleiades. Take the roll of film to your local Boots the chemist, (other chemists are now available), and several days later when you picked them up were surprised by what you were charged. It was far less than usual. You'd be charged for the processing but only for what they'd printed. Those few darkish spots on a transparent background meant that the negative was not printed, the same thing that would happen had you'd left the lens cap off. :(
To older readers this may bring on a touch of nostalgia, for others you'll probably be wondering what the heck I'm on about. Why didn't I simply take the SD card and select what I wanted printed myself.
The youngsters of today don't appreciate how much easier and safer life has become. :)
Cheers,
Ray
Ray
Roboscopes Guinea Pig
I have been learning more about star evolution and came across the amazing Herbig-Haro objects. High energy jets pumped out by protostars as they light up.
I know that they are found in star-forming regions and wanted to see if I could pick one up.
The most accessible at this time of year is HH 555 in the Pelican Nebula (IC5070). So I put in a narrowband close-up of the Pelican (job 1622). This is what I have produced. It is not perfect, but at the tip of the dark tongue of dust in the centre is a pale blue bar at right angles to the dust cloud. That is HH 555. We would need more data and possibly a higher resolution to see it more clearly, but I achieved the goal. It is quite an attractive image in its own right.
Hi Richard,
That's an excellent result you've produced. I had a quick look at that dataset and thought, that's going to be a bit of a challenge, hoisted a white flag and then moved on to the next set. Great job on the stars particularly the pair by the tip of HH555.
I wouldn't be averse to collecting more data while it's well placed either.
Cheers,
Ray
Ray
Roboscopes Guinea Pig