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PostPosted: Sat Dec 29, 2007 10:06 am 
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HI Bob, Gordon,

I take all the data from the New Forest Observatory - colour-convert and stack the subs - then send via broadband to Noel Carboni in Florida U.S.A. who creates the final work of art.

I'm not sure you need Maxim DSLR for processing unless you want some other functions it offers. If you have Photoshop, or Photoshop Elements what you want is Noel Carboni's actions (all of 10 quid) which are an extensive set of procedures specifically for processing astronomical images. I think Noel will be joining this forum shortly, so you can get the full low-down from the master himself :)

As you say - the H-alpha can be blended in at a later stage and it provides a higher contrast template than the RGB as it effectively "darkens the background" making you imaging site appear to be darker than it really is. However - you still benefit by having a dark site even with narrowband - the contrast just gets better.

With regard to DLSR versus a dedicated astronomical CCD imager. Although DSLRs have been shown to give very good results - you are really asking these things to work outside the zone they were designed for. The filter taking out the most important emission wavelength [H-alpha] is one problem, the second problem of course is that the CCD in a DSLR is not cooled. With an astronomical CCD it is not an issue to take sub-exposures up to an hour long, with no thermal noise penalty - something that simply is not possible with a DSLR.

All the best,
Greg

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Nexstar 11 GPS, 2 x Sky 90, M25C, MaximDL, Photshop CS3, Noel Carboni's Photoshop actions, 7 foot Pulsar fibreglass dome, Canon 40D, 100mm macro lens, 28-200mm zoom lens, 17-55mm f#2.8 zoom lens, 100-400mm zoom lens, 1.4x converter, 2x converter.
http://www.newforestobservatory.com/
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PostPosted: Sat Dec 29, 2007 4:10 pm 
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Hi Greg,

Many thanks for the feedback and also for pointing me towards "Noel Carboni's actions" which I promptly bought. I spent a good few hours this afternoon starting to familiarise myself with them and they certainly help unlock astronomical image processing power I didn't know Photoshop had. I'm delighted with the purchase, though there is a huge temptation to keep fiddling and end up losing more than you gain. :evil:

I certainly take your point about the lack of cooling and consequent signal noise from DSLR sensors. However, I was very pleasantly surprised by the sensor noise from my 40D with a 30 minute exposure (see this post).

Bob.

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PostPosted: Sat Dec 29, 2007 4:31 pm 
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Hi Gordon,

I really wasn't happy with that 100% crop of the Horsehead Nebula I posted above. It was never going to be good as the image is effectively being plucked from only a few bits of the 14 bit signal from the 40D, not to mention the camera's lack of sensitivity to the Hydrogen Alpha emission line, but I thought I could do better. This time I stacked eleven crops from the frames that I used to create the Orion Constellation mosaic above.

Processing in IRIS was much the same (though I used two passes to remove the background gradient). However in Photoshop I was able to use some of Noel Carboni's actions for the first time to unlock Photoshop's true power. Of course it's impossible to reveal detail which just isn't there to start with but I think the final 100% crop is an improvement.

    Image
Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Sat Dec 29, 2007 8:18 pm 
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That does look better Bob... What exactly do Noel's actions do - without giving away too many secrets!


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PostPosted: Sat Dec 29, 2007 8:49 pm 
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Gordon Laing wrote:
That does look better Bob... What exactly do Noel's actions do - without giving away too many secrets!

Have a look at his Astronomy Tools Entire Actions Set web page. This is the page for the full Photoshop program but there is also a version for Photoshop Elements.

I had never used "actions" until today so my summary may be incorrect but as far as I can tell they are just scripts coordinating a sequence of Photoshop functions. That description is misleadingly simple, however. I would never have guessed that you could use Photoshop to automatically select all of the bright stars in an image. Once done you can either perform a Photoshop function on those stars or "invert" the selection and operate on the rest of the image. Some of the actions really get Photoshop stretching its legs. This afternoon I had all four Opteron cores running near 100% and 3.5GB of memory usage. :shock:

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Sat Jan 05, 2008 1:35 pm 
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Hi folks,

What with the Moon and cloudy skies things have been quiet here on the astrophotography front so I thought I would have a brief play with Noel Carboni's Astronomy Tools. My starting point was the JPEG images posted previously.

The action of choice today was "Make Stars Smaller". Making the stars smaller is a neat trick which results in a rather dimmer and initially less attractive picture but it means that the brightness and contrast can be boosted which gets the stars back roughly to where they were and so enhances any nebulosity.

As an example, here are 100% crops from the thumnails. The one on the left is processed as described while the one on the right has been processed to try (very roughly) to match the brightness of the nebulosity. To my eye the boost in the brightness of the stars is too fussy and they still tend to drown out the fainter nebulosity.
    Image.......Image
Probably not the best area to crop to demonstrate the fairly subtle effect but it shows up rather better in the full sized thumbnail:
    Image
    Clickable if you want to see the full sized version (4MB) which was processed separately
Comparing this with the thumbnail posted here the nebulosity above and to the left of Orion's belt shows up much better while the background of fainter stars retains roughly the same visual density.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Fri Apr 10, 2009 2:11 pm 
Bob, a stunning and interesting thread though I am going to have to read it several times. Have you ever thought of taking a trip up into the Welsh mountains or the Scottish highlands even the N.Irish Antrim coast to try some star shots? I live around Belfast but have once or twice been up around the likes of Murlough bay and Torr head on a cloudless and clear night and, even to the naked eye, the sky is absolutely breath taking.


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PostPosted: Thu Dec 10, 2009 3:09 pm 
I'll be honest. I don't understand why people love these refractors. They are just so weak imho. Why not go with a powerful sct?


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PostPosted: Thu Dec 10, 2009 3:33 pm 
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.
No diffraction spikes caused by the secondary mirror support and virtually zero maintenance. But they do have limitations if you want the biggest light bucket for your buck.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Thu Dec 10, 2009 8:18 pm 
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Not only spikes, but the sheer size of the secondary mirror blocking the view as well - with a refractor at least you're getting all your aperture!

They do have quite different qualities too - a good refractor can be incredibly sharp and contrasty. But yes, if you want a big light bucket and a short tube, then an SCT is hard to beat.


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PostPosted: Fri Dec 11, 2009 2:01 pm 
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My Sky 90 (3.5 inch refractor) outperforms my C11 (11 inch Schmidt-Cassegrain) using the same imaging camera - for certain objects. The improvement in contrast is quite unbelievable - and a case where the Sky 90 was a better imager than the C11 was the Regulus and Leo 1 (galaxy) shot in this thread. The C11 would not have pulled out Leo 1 from the glare of Regulus.

Greg

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Nexstar 11 GPS, 2 x Sky 90, M25C, MaximDL, Photshop CS3, Noel Carboni's Photoshop actions, 7 foot Pulsar fibreglass dome, Canon 40D, 100mm macro lens, 28-200mm zoom lens, 17-55mm f#2.8 zoom lens, 100-400mm zoom lens, 1.4x converter, 2x converter.
http://www.newforestobservatory.com/
http://www.flickr.com/photos/12801949@N02/


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PostPosted: Mon May 24, 2010 11:49 am 
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Hi all,
Just wondered if anyone could find a tuturial for IRIS. I got DSS already, is it really needed to use IRIS too?

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PostPosted: Mon Jan 10, 2011 12:44 pm 
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Hi folks,

Well, it's been a while since my last attempt at astrophotography as my old ThinkPad gave up the ghost at about the same time as I sold my 40D in favour of a 5D Mark II. The final nail in the coffin of my astrophotography was the realisation that I'd also need a new light pollution suppression filter as the one I had used on the 40D (and the 400D before that) was way undersized to be usable on the full-frame 5D2.

Anyway, I recently dipped a toe into the world of Apple and got a MacBook Air which can control my 5D2 courtesy of Canon's EOS Utility software. I also invested in a 72mm IDAS LPS filter so the only thing stopping me from getting out in the cold night air was, I'm sorry to say, lethargy coupled with some inclement weather.

Last night I tried to put that right but the observing conditions were, to say the least, unfavourable with a thin high level cirrus drifting in and out of the field of view making it very difficult to predict which shots could be exposed as "lights" and which as "darks". For more on "lights", "darks" and much else you can check out the IRIS tutorial here.

In the end I captured seven "lights", plenty of darks (all exposures were 120 seconds) and, together with some bias and flat frames made earlier, I set to work with the free IRIS software. Seeing was so poor when I set up the telescope that I couldn't see Polaris in the mounting's polar finder so I did the best I could. Not good enough as it turned out as each star was elongated into a trail several pixels long. :evil:

As a result of all of this the final image is not pretty and is very much a rescue effort which owes more to post-processing finagles than scientific accuracy. The image is in the vicinity of Auriga and was captured with my 5D2 plus EF 85mm f/1.2L USM wide open at f/1.2, with the camera piggybacked on top of the telescope and so using the mounting to track the stars. IRIS did the initial processing and PhotoShop was used to finish it off.
    Image
I'd hoped to capture more of the nebulosity in the region but ineptitude on my part coupled with the conditions on the night have served to remind me how hard one has to work to get good results.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Mon Aug 29, 2011 11:00 pm 
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Hi folks,

Earlier in the thread I included a number of posts about the North American Nebula. The images were pretty awful and the one I'm about to share isn't great either as it has been over-processed to bring out the nebulosity and suffers from the usual DSLR insensitivity to Hα. Hopefully I will do much better in the future when I can concentrate on narrowband imaging using a dedicated astronomical CCD camera with a consequent emphasis on the nebulosity without masses of big fat stars cluttering up the shot. :roll:

The final image was the product of 14 two minute exposures with my EOS 5D Mark II at ISO 400 using my 85mm lens at f/1.2 with an IDAS light pollution filter fitted. The camera was piggybacked onto my new ASA DDM60 Pro equatorial mount so the imaging session at the beginning of this month was as much about testing tracking accuracy over the hour or so that it took to acquire the "lights" as it was about the North American nebula. A suitable number of dark, bias and flat frames were also acquired.

Post-processing was done largely in a trial version of PixInsight with a few finishing touches in PhotoShop. This was my first day with PixInsight and I am already mightily impressed. The UI is a little unusual for a Windows user but it's easily learnt. The software understands Canon RAW files as well as the usual file formats and there are plenty of tutorials which can be found via the PixInsight website. But make no mistake, those tutorials are vital as the software not only has a huge range of things it can do but there are often a huge range of options for each action. It does make good use of all available processor cores though so experimenting with settings isn't too time consuming. Anyway, enough rabbit from me! Here's a central crop from the final image:
    Image
Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Mon Aug 29, 2011 11:34 pm 
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Ooh, nice. Is it that time of year again? I never got the 450D converted so I should move on now before I miss another season. Need to fix/replace my polar finder too.

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