The Rosette Nebula in H-alpha!
45x1' ISO3200 f/2.8 + darks/bias
iOptron Skyguider Pro
Astronomik 12nm H-alpha
I love to be back!
@fedops thank you! It is, yes, 135mm is quite wide for that nebula. Will show later an individual frame for reference, or the stacked version with the correction frames included.
@kosmoplan thank you, I would love to see that. That's fascinating, I always thought you need meters of focal length to be able to do anything.
@fedops you don't, and actually that requires very fine tracking (hence computers, or guiding). Wide angle lenses are much more forgiving when it comes to that, and if one takes time aligning they can reach 1-2 minutes exposures with a very lightweight, portable rig. Perfect for the urban astronomer! 😎
@fedops there, an almost raw master with just some scaling down. Gradients, noise, etc., straight from the stacking.
@kosmoplan interesting. What does the H filter do exactly - block parts of the visible light? Is that what makes it work in light-polluted urban environments?
@fedops Correct. Ha means the filter just lets light at 656nm wavelength to pass through (a window centered there, in my filter case, a 12nm window). This is the best way one can take pictures from urban environments. The only thing is, of course, the result is not in RGB, so usually astronomers combine three sets of images at different wavelengths to create a colour picture 
@fedops I'll let Sara Wager (one of my favourite astrophotographers) explain to you the OIII and SII filters, and how one can use the Ha as R (if using Ha alone) or G (if you own a SII too) and create what's called the "Hubble Palette". Very beautiful RGB pictures!
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