This is an image of IC5148 Also commonly known as the spare tyre nebula. It contains 38.25 hours of data and 25 hours of OIII data to bring out some of the halo. I was inspired to do the image based on the two images I have seen of it which show the fain halo; Don Goldman's and Mike Sidonio's images.
One of the by products of imaging this target was an interesting evaluation of two different imaging rigs from mine. One being Don's 20 Planewave f6.8 with Apogee U16M camera and the other Mike's 12" f3.8 Orion AG and Starlightexpress H694 sensor. Based on what I have gathered it appears that I would need about 55 hours or more of OIII data to equal Don's image and probably about 40 hours or slightly more OIII data to equal Mike's image. Such is the difference in the imaging speed of both scopes. Don's being a bit slower at f6.8 has the advantage of diameter over both the 12" scopes. Mike's scope has the fastest imaging speed and is remarkably close to Don's image. Clearly f8 has its disadvantages (focal length is its main advantage) and I will be considering this issue when I do eventually replace the 12" f8 I have at present. In any event it appears I need to do something like 3-4 times the integration on very faint targets for now.
As to the image I have produced, I really like the addition that the RGB data had to the NB data. If you look around you can see galaxies in the field with some very faint ones being seen in the background. It is a very interesting looking target and I have enjoyed imaging it.
Great detail and colour and you got some of that extra halo starting to show through. Very nice.
Aperture, F ratio and camera QE are a like a triangle for imaging speed. I have been impressed by how fast the Honders accumulates data with the Trius.
Of course every system has its advantages and disadvantages but there are quite a few scopes these days that have both aperture and fast F ratio. IDK,Harmer Wynne astrographs, Officina Stellare, OOUK, AP RHA are a few. Ceravolo F3.9 300mm was one of the first. I have often wondered do you get the same result of long focal length by using a small sensor on a fast scope. So far my experience is that it is similar but there is no substitute for aperture at the end of the day (or darks skies!). But fast wide aperture scopes like Mikes Astrograph or my Honders with a smaller chip with smaller pixels seems a little less sensitive to seeing than longer focal length with larger pixels. I am not 100% sure of that but so far it seems it is.
Greg.
Last edited by gregbradley; 20-10-2015 at 07:46 PM.
Such a small target Paul, but so crisp! And yes, I spent a good few minutes galaxy hunting in your lovely image.
I too am realizing that aperture and F ratio are the key. I'm building a new scope, 250mm aperture f4 versus my tak's 130mm f3.3, should suck in a fair bit more light
I agree - it is very illustrative to compare the different imaging setups and efficiency etc.
I also have been capturing this target over the last month and will probably have 40 to 60 or so hours of LRGB HaO3 data in total....I will get onto processing this data as a comparison - taken with the 4750mm focal length 20 inch with a PL16803.....
Cheers,
Tim
Great shot, Paul
I’m working on this one too, just the equipment is, so to speak, not comparable (FLT132+2xTeleVue Powermate) … but the TYRE is there …
(single shot in O3, slightly stretched)
quite an interesting discussion regarding imaging setups. personally I like the idea of having an 16" f4 newt and having the additional option of f8 via 2x barlow/powermate for smaller targets. would be maxing out an eq8 however... and an obsy is a must.
Bravo! Most minute detail in such a tiny target. I particularly like the super-fine almost overlapping shells in the main bright part of the nebula. One wonders if the true three-dimensional shape is a double cone seen axially.
The tiny galaxy and the bright orange star in the near field make for a photogenic background.
I will be considering this issue when I do eventually replace the 12" f8 I have at present. In any event it appears I need to do something like 3-4 times the integration on very faint targets for now.
Nice work Paul,
I don't know how you have patience or the time.
So - share with us all please -
what is your next telescope idea?
How about a 24" f3 Newt.?
That would pull in the faint ones & still have 1.8 meters of focal length
which would match the best seeing possible.
Nice work, Paul! It's a cool object and you've captured and processed it very well.
I first saw the Oiii halo faintly in an image by Martin Pugh. I have 75 hours on this object from last year that I should probably finish processing. Unfortunately, I wasn't able to get anywhere near the detail in the Oiii halo that Don Goldman had in his inverted image (and no other image that I've seen has come close either.) I think that with his aperture and image scale he's able to take read noise limited subs in a manageable time which is something that those of us with 12" scopes can only dream about in narrowband. Still, it's fun to try
Thanks Ian, Lewis, Mark, Slawomir, Russell, H, Lee and Erik for the comments. Thanks for taking the time to contribute.
Quote:
Originally Posted by gregbradley
Great detail and colour and you got some of that extra halo starting to show through. Very nice.
Aperture, F ratio and camera QE are a like a triangle for imaging speed. I have been impressed by how fast the Honders accumulates data with the Trius.
Of course every system has its advantages and disadvantages but there are quite a few scopes these days that have both aperture and fast F ratio. IDK,Harmer Wynne astrographs, Officina Stellare, OOUK, AP RHA are a few. Ceravolo F3.9 300mm was one of the first. I have often wondered do you get the same result of long focal length by using a small sensor on a fast scope. So far my experience is that it is similar but there is no substitute for aperture at the end of the day (or darks skies!). But fast wide aperture scopes like Mikes Astrograph or my Honders with a smaller chip with smaller pixels seems a little less sensitive to seeing than longer focal length with larger pixels. I am not 100% sure of that but so far it seems it is.
Greg.
Thanks Greg, I think that something like a 16" with a focal length of around 2400mm or slight longer would be the go. That would give an f ratio of 6. I don't think focal lengths under that are useful to me for what I would like to image. It's an interesting conundrum.
Quote:
Originally Posted by SimmoW
Such a small target Paul, but so crisp! And yes, I spent a good few minutes galaxy hunting in your lovely image.
I too am realizing that aperture and F ratio are the key. I'm building a new scope, 250mm aperture f4 versus my tak's 130mm f3.3, should suck in a fair bit more light
Thanks Simon, this is why I have two rigs; one for long focal length work and one for the wide field stuff. There would be too much of a compromise otherwise.
Quote:
Originally Posted by topheart
Good one Paul!
I agree - it is very illustrative to compare the different imaging setups and efficiency etc.
I also have been capturing this target over the last month and will probably have 40 to 60 or so hours of LRGB HaO3 data in total....I will get onto processing this data as a comparison - taken with the 4750mm focal length 20 inch with a PL16803.....
Cheers,
Tim
Thanks Tim, now that will prove rather interesting. I will look forward to that.
Quote:
Originally Posted by Placidus
Bravo! Most minute detail in such a tiny target. I particularly like the super-fine almost overlapping shells in the main bright part of the nebula. One wonders if the true three-dimensional shape is a double cone seen axially.
The tiny galaxy and the bright orange star in the near field make for a photogenic background.
Thanks Mike and Trish, that is a distinct possibility about being a double cone seen axially. I had not considered that until now, but now that you mention it, that does make sense.
Quote:
Originally Posted by alpal
Nice work Paul,
I don't know how you have patience or the time.
So - share with us all please -
what is your next telescope idea?
How about a 24" f3 Newt.?
That would pull in the faint ones & still have 1.8 meters of focal length
which would match the best seeing possible.
cheers
Allan
Thanks Allan. It won't be a Newtonian. It would not fit in my dome. So I am inclined to look at something like an f6 16" (with reducer if necessary). 2.4 metres is my aim for focal length.
Quote:
Originally Posted by RickS
Nice work, Paul! It's a cool object and you've captured and processed it very well.
I first saw the Oiii halo faintly in an image by Martin Pugh. I have 75 hours on this object from last year that I should probably finish processing. Unfortunately, I wasn't able to get anywhere near the detail in the Oiii halo that Don Goldman had in his inverted image (and no other image that I've seen has come close either.) I think that with his aperture and image scale he's able to take read noise limited subs in a manageable time which is something that those of us with 12" scopes can only dream about in narrowband. Still, it's fun to try
Cheers,
Rick.
Thanks Rick, agreed, Don's superior aperture has it over the rest of us. Still I like to try. There is always a limit to what can be achieved but like you say it is fun to try.
Paul i think you have done a fantastic job getting even a hint of those elusive OIII outer regions from an F8 setup.
The Nebula shells look very sharp and well defined though the edges of the shells aren't as bright and vibrant as Mike's.
I really do hope i can achieve results near as good as yours with my GSO RC when i get it working properly
