A new Helix Nebula image

[tornado33]

Hi all
I havent actually taken a new image, what I tried was combining my Baader UHCS filtered shot with an older unfiltered shot, using Photoshop CS, manually stacking (and rotating) the 2 images to get all stars lined up. Here is the result
http://www.users.on.net/~josiah/baad...teredsmall.jpg (full frame image)
Compare with http://www.users.on.net/~josiah/baad...teredsmall.jpg which is the Baader filtered shot, and http://www.users.on.net/~josiah/temp/helix45min.jpg (Both cropped)
The unfiltered one gets mostly blue, whereas the filtered shot gets plenty of red, the combo a more even balance of both. The filtered component is 10 and 15 min ISO 1600 shots, the unfiltered part is 3 x 15 min ISO 400 shots.
This is the great thing about computers, one can go back to old images and combine them with more recent ones. Even ones taken with different telescopes could be combined you'd just have to resize them to the same image scale.
Scott

[[1ponders] (Paul)]

Don't know quite what it is about the new one, whether its slightly darker with slightly more intense colour, less red in the surrounding space or because its slightly more details, but I do like it better than the other two. Not that there is anything wrong with either of them. Subtle changes can certainly make a difference.

[tornado33]

Yes it was just an exercise to see what I would end up with, basically the more images that go in to the final product, the less noise and smoother the result (In theory).
Scott

[janoskiss (Steve H)]

Scott, the first two links in your post are the same.

[davidpretorius]

will you see the lovely blues and reds via a 10" or 12" dob with or without filters.

[tornado33]

OOps sorry about that, I mucked up the links
here is the final image http://www.users.on.net/~josiah/baad...teredsmall.jpg
This is the Filtered only image http://www.users.on.net/~josiah/baader/helixbaader.jpg
This is the filterless only image http://www.users.on.net/~josiah/temp/helix45min.jpg
Scott

[tornado33]

A fair question Dave P
Sadly colours of the helix cannot be seen visually no matter the scope size, as its not a matter of size but surface brightness. The total brightness of the Helix is quite bright, but because its so large, its surface brightness is low, not enough to activate the cells of the eye retina that sense colours. Bigger scopes show a larger image but not of higher surface brightness. Going to lowest power eyepieces makes it brighter but only to when the exit pupil from the eyepiece is smaller than the iris of the dark adapted eye. Going lower means a bigger exit pupil, some light will be lost, so the image will not appear brighter, just smaller.
This explains the exit pupil concept http://www.singularsci.com/Accessories2.htm
Scott

[janoskiss (Steve H)]

Originally Posted by davidpretorius

will you see the lovely blues and reds via a 10" or 12" dob with or without filters.

With or without filters, you will not see colours in DSOs. With colour filters you'll only see the colour of the filter. Planets have colour though, as do many stars: blue, red, orange; this makes many open clusters very pretty.

[davidpretorius]

so only on film, will the colours become apparentof dso's?

[astro_south (Andrew)]

Some bright DSO's will show subtle colour given the right conditions. I have seen greens and ruddy pinks in the Orion nebula through my 12.5" and I have seen some red/pink on the Trifid Nebula in a 16" dob. Planetary nebulas can show colour, but generally Steve is right - no colour on galaxies and faint nebula.

[janoskiss (Steve H)]

David, perhaps you should have a look at this page, Ken posted recently. Look at the example pics of nebula in a colour photo vs in a (very large) scope.

[RAJAH235]

Scott, nice pics. Good detail in the 1st one.
David, Your eyes process the info/photons instantly, unlike a 'film' or digital camera which accumulates them. It takes a very bright object for your eyes, 'CONES for colour' receptors to react/collect the light so that you see any colour.
As Andrew has said, you will see colouration in nebula, given a large aperture & seeing.
I've seen very slight 'green' in the Orion neb thru my 10", on nights of excellent seeing etc. L.

[davidpretorius]

thanks all, it makes sense.

[ving (David)]

Originally Posted by davidpretorius

will you see the lovely blues and reds via a 10" or 12" dob with or without filters.

they are right of course. most DSOs wont show any colour at all. though that said, thru my 8" m42 is a brilliant green and some other nebulars show some green colouration too. another nebula that shows stunning colour id the ghost of jupiter nebula... try hunting it down.

as for the helix, its hard enuff to see as it is. it a huge nebula but its dim. alot of skycharts and astro programs give it a fairly bright magnitude but they get this number by condensing all the light produce by the object into a pin point... of course the light is spread out and so therefore is much dimmer that thier claimed magnitude. The helix is situated about half way inbetween the bottom star of capricorn and procyon (the bright sat to the right). use a low magnification EP and a LPR filter if you have one and good luck

I feel like an expert now I have found it

[davidpretorius]

"David, perhaps you should have a look at this page, Ken posted recently. Look at the example pics of nebula in a colour photo vs in a (very large) scope."


This is a good read, thanks