Light capture and darks caused me to spent all night on these two.
65 minutes on Sombrero, darks subtracted.
55 minutes on Trifid, Darks subtracted
Imaging scope- Skywatcher ED120 APO refractor on an EQ6Pro
Guide scope- Skywatcher ED80 APO refractor piggybacked
Imaging camera- Orion Starshoot Pro OS DSI
Guide camera- Orion Starshoot autoguider.
Captured with MaxIm DL essentials
Post processed with PS elements 6
Hope you like.
Baz.
(http://i42.tinypic.com/2pq6olt.jpg)
(http://i42.tinypic.com/10olidh.jpg)
wow! fab images
c
Baz,
They are much better then your previous images, well done.
Chris
Thanks Carol and Chris.
There is a bit of a green hue to the Sombrero that I am reprocessing now. I think I need a good barlow. At this scale, I find it pretty uninteresting.
Baz.
Baz - I think if you start using a barlow with the ED120 your exposures will become extremely long.... I take it the images you have displayed are the full FOV - I think the Orion starshoot has a very large chip - 6.1Mp - Is this the model you have? - Why don't you do a crop of the area of interest i.e. sombrero or triffid & display it at 100% size instead of displaying the whole image at something like 20% size....
Deep sky imaging & barlows don't really goto very well in my limited experience...
John
Quote from: JohnP on Mar 30, 2009, 13:54:40
Baz - I think if you start using a barlow with the ED120 your exposures will become extremely long.... I take it the images you have displayed are the full FOV - I think the Orion starshoot has a very large chip - 6.1Mp - Is this the model you have? - Why don't you do a crop of the area of interest i.e. sombrero or triffid & display it at 100% size instead of displaying the whole image at something like 20% size....
Deep sky imaging & barlows don't really goto very well in my limited experience...
John
Hi John,
With a fully automated imager and mount, I really don't mind the longer exposures. The noise I can tackle...
In my own limited experience, every time I have cropped an image and displayed it larger, the artefacts really start to show. I think the trade off with a barlow is acceptable, but it will depend on the quality of the barlow. I see a few around for about 80 bucks, but I am thinking more like $450 (AUD) For a good Televue 2x
Baz.
Baz - I'm still not convinced - Any chance you can either email or post up the full sized stacked image so I can see how bad noise & artifacts are...
You probably already know but the greater the f-number the less light per unit area reaches the imaging plane or CCD. I think your ED120 is a f7.5 which in terms of Deep objects is already pretty slow.. If you use a X2 barlow this will increase to f15... The amount of light reaching the CCD decreases with the f-number squared. So if you double the f-number you will have to increase the exposure time by 4 just to capture the same amount of signal.... i.e. reasonable 5min subs become 20mins...!!!!!! You will also be imaging at a much longer focal length 1800mm instead of 900mm which means tracking & guiding will become extremely difficult.
I still think a 100% crop of the full FOV is the way to go.. 900mm is a good length for most nebula's (small one's) & galaxies. If noise is an issue just stack more exposures. Artifacts can normally be cleaned up with good flats, darks, bias frames & if necessary Photoshop in the post processing stage...
Lets see a full sized image,
John
Awww...sorry John, I actually already disposed of the pic. I'm so not happy with it I am going to re-shoot it entirely. My focus was too soft and I found out that my focus subframes in MaxIm are too long in exposure. If I shorten the exposure, I can achieve better focus.
Failing that, I will try both your way and the barlow way. I need a barlow to shoot the ISS anyway, so I might as well get one.
BAz.
ISS & barlows are OK because it is a really bright object so SNR is very high... NOT DSO's though..... :-)
Shock horror throwing away images..! those two images you posted both looked very nice & in my books would have definitely been keepers. I've never discard raws no matter how poor they are....
Cheers & look forward to more - John
Baz,
Never ever throw away astronomical data!
For instance you could well find that one or more of your frames caught the beginnings of an important event e.g. supernova, near earth object, satellite explosion or collision.
You would kick yourself very hard indeed if you later realise you had discarded something unique. Morever, however "bad" the image, it could even provide valuable scientific data.
Mark
LOL!! You guys!!! ;)
I said I threw out that image. Let me clarify, the finished stacked and processed image....
I still have all the subs, but like I said, the focus is too soft and I wand to shoot it again.
LOL!
:lol: :lol:
Well I'd be interested in seeing even a raw from the triffid image - looks like there is loads of detail there...
John
Lovely images Baz, your technique seems to be improving and the results are looking really good.
I'd agree with you in the scale of the sombrero but the Triffid has a lot of dark nebulae surrounding it so I think it's about right. It could do with more subs to bring out some of that dark stuff though. Also for some reason the stars in the lower left seem more in focus (to my eyes) than top right but it's only on the Triffid.