Nebulosity is a hard program for the aged?

[sophiecentaur]

I have been using Nebulosity to stack multiple images. Doing just that was not beyond me and lo! the noise level drops impressively. I then needed to get the colours to work. De-mosaicing (disgusting word) is necessary to produce a .fit file from .dng. Using the pre-sets in the dialogue (a 3x3 RGB Matrix) gives me greens when the original image of the Orion Nebula is violet (ish). Some random tinkering produces some random colour variations. I am presuming it's something to do with my (Brand New totally FAB) Pentax K2s's Bayer filtering. There must be a way to customise Nebulosity to handle this but I can't find any information - needless to say, the Neb manual never falls over backwards to help a chap.
Anyone else been there and solved it?

 

[russ_watters]

I can't answer your specific question, but as for the title, it isn't just the aged; most astronomy software I've used is not very refined.

 

[sophiecentaur]

Yeah. I have written many many procedures that only I could make use of. You could call it Nerdware, perhaps.

 

[Andy Resnick]

I have been using Nebulosity to stack multiple images. Doing just that was not beyond me and lo! the noise level drops impressively. I then needed to get the colours to work. De-mosaicing (disgusting word) is necessary to produce a .fit file from .dng. Using the pre-sets in the dialogue (a 3x3 RGB Matrix) gives me greens when the original image of the Orion Nebula is violet (ish). Some random tinkering produces some random colour variations. I am presuming it's something to do with my (Brand New totally FAB) Pentax K2s's Bayer filtering. There must be a way to customise Nebulosity to handle this but I can't find any information - needless to say, the Neb manual never falls over backwards to help a chap.
Anyone else been there and solved it?

Haven't used Nebulosity, but I do know that accurate color rendering is a major hassle in astrophotography. The only "Gold Standard" I have come across is to export your .fits image into eXcalibrator: http://bf-astro.com/excalibrator/excalibrator.htm

Good luck... let us know if you figure out a better way!

 

[sophiecentaur]

This is far more extreme than 'accuracy' problems, I think. It's almost as if RGB has been interpreted as CMY; the green I am seeing is much the same as minus magenta (the colour of the original picture)
But then the sky would be white?

 

[sophiecentaur]

Just to bring this colour thing to a close. Nebulosity doesn't know enough from my DNG file format to do the right de-mosaicing. I used Aperture (OS X) to produce a 16bit Tiff file and nebulosity seems to be able to make sense of it, producing just the same colours as the original (ignoring any 'casts', which are second year work, as far as I'm concerned)
The noise improvement from using just ten exposures is impressive. I will post a picture (Orion Nebula) when I have re-done the exposures with the Sky tracker properly aligned. I had to chase around the garden to get pictures at the time and my carefully setup mount was the first casualty. But you expert after-dark workers will know all about the confusion of working without lights.

 

[Chronos]

AP, and photography in general, is a complex process that requires numerous factors to be taken into account. The chief goal is to render an image pleasing to the user. They do a pretty decent job at that, on the whole. Low light photography is particularly challenging because of the need to extract every microEV of useful energy out of each captured photon. Asking that to be a user friendly process is a tall order.

 

[sophiecentaur]

AP, and photography in general, is a complex process that requires numerous factors to be taken into account. The chief goal is to render an image pleasing to the user. They do a pretty decent job at that, on the whole. Low light photography is particularly challenging because of the need to extract every microEV of useful energy out of each captured photon. Asking that to be a user friendly process is a tall order.

You could say the same about almost any complex software. It is very possible (not easy) to make software straightforward to use. Take Photoshop and Excel, for instance. The sky's the limit to their capabilities and subtleties and they are both pretty approachable. The difference between them and Nebulosity is the amount of work that's put into their development which reflects on the money they can make the distributors. More specialist software just can't have the amount of development time and it shows, as soon as one fires it up. It's an alien world in there.
It seems to me that Nebulosity was probably developed by a small group of enthusiasts for their own esoteric use and gradually expanded for distribution. I fully sympathise with the writers in most respects because they are primarily interested in what the software does for them with AP files. It must be a real pain (i've been there) to produce endless upgrades and bug fixes, just for the general user. I will contact them and tell them about my DNG problem - just to add to their tiresome worries.
Bottom line is, though, that Nebulosity has made things possible for me that I couldn't have achieved without help. It works on OS X and does a lot of what's needed so I'm better off with it than I would be without it.