Ou4 (and SH2 129): A Giant Squid Nebula and a Flying Bat

[Boren]

Wow! Spectacular imaging! Something from the "Outter-space":-)

Thanks gingergeek, GIna, Mr. Bergman,

I'm very happy you liked it and thanks for these warm words.

Cheers,

Harel

[laser_jock99]

Cracking image of a very faint subject!

[Knight of Clear Skies]

Is this the reality of the subject photographed? Is this what we are actually looking at? I believe that the answer is both a yes and a no...

Thanks for the response, very interesting to learn a bit more about your workflow and the reasoning behind it. I agree that a processed image is an interpretation of real data. It makes sense that bringing in a faint and interesting object - such as the squid - will inevitably require compromises. It didn't occur to me that your star colour might be altered by a faint OIII signal in front of them. Thinking about it I've come across this problem even in my basic RGB imaging, such as this Veil Nebula test shot. Despite the simple processing the fainter nebulosity only shows as a discoloration of the background stars. (It's probably over-saturated but my objective was to bring out the Veil and I have a limited toolset at my disposal.)

It's a subject I'm interested in learning more about. I enjoy the aesthetics of astronomical images but I also like to understand the reality behind them and the physical processes at work, at least as far as I am able. "What colour is the squid?" is a really difficult question to answer. The OIII component is certainly teal but what effect does reflection nebulosity and the presence of other elements play? There are many approaches to imaging from scientific to focussed on aesthetics and anywhere in between. I see them as complementary and enjoy seeing different interpretations of the same object. Knowing a bit more about how an image was constructed helps with the interpretation.

Even a linearly stretched RGB image is somewhat deceptive. After all, stars are point sources really - but not by the time the photons pass through an atmosphere, optical system and hit a detector. Even if we could construct a scope with a ridiculously low focal ratio - allowing us to see truly faint DSOs - I suspect the glare from any bright stars in frame would prevent us from doing so. The human eye didn't evolve to hunt down that sort of fuzzy. And as you say, we're only seeing a fraction of the full spectrum anyway.

You might find this thread interesting, it touches on some limitations of human vision.

[Simon Dinossauro Webb]

Amazingly beautiful!