I'm finding that morning twilight is the best time for imaging. This is a result from Sunday morning at 5.39am - not long before sunrise.
I set the scope up at sunset and then just tried to get the mirror down to the right temperature by 3am using a peltier cooler. After that I just switched everything off and let it sit until 4.30.
I imaged 700 frames in each of red,green,blue through filters and then batch processed 100 frames of each to give me 7 masters for each colour.
Finally combining those 7 masters in each of red,green,blue gives this result.
10" f/6 newtonian
4x TV powermate
Astronomik RGB filters
fire-i monochrome firewire camera
captured with Coriander for Linux
processed with Registax and Astra Image
in Windows.
You are certainly giving us images to aspire to Bird
I'd really appreciate it if you could expand a bit on your capture and processing techniques.
I know you shoot in B/W but what # filters are you using. I have a #80 blue (light blue 30% Trans), #25 red (14% Trans) and #58A Green (24% trans) would these be suitable or do I need specific RGB filters.
How did you seperate the 100 images from the 700, and were you selecting for something specific?
I assume you processed each of the 100 in Registax to achieve your 7 masters. Then you combined them in Astro Image (I'm not familiar with this program. Any comments on it?) If you were to use Photoshop do you know how it could be done?
I've still got another week on holidays so you can make your response as long as you like, I've got plenty of time to read it at the moment.
Thanks for the great images and any help you can offer
There's quite a bit to describe, but I'll try for a quick overview and see if it's the sort of info you're after.
To get high quality raw frames needs a scope that's tracking as close to perfect as you can get. I spend about 30 minutes on polar alignment, to the point that Jupiter will stay on the CCD for an hour or so if I wander inside to get a coffee or some sleep :-) It's important because a moving object will contribute to blur at the relatively long exposure times we are all using (I was using 40ms for these frames).
I wait until just before starting to image to check and adjust collimation, so that everything is cold and in its final position. The screws on my scope have been replaced with with hex key headed bolts, so I can use an allen key to adjust everything. It's easier to make fine adjustments that way. I make sure the scope is pointing roughly where it will be used when I set the collimation, cause I know that the collimation won't stay put if I swing from one part of the sky to the other.
I have a homemade 10" f/6 newtonian. The glass mirror was made by Mark Suchting in Sydney. He is well regarded for good quality mirrors and makes quite a lot of large (20+ inch) mirrors.
The tube was made by Gary Mitchell in Sydney out of 1mm thick aluminium. Aluminium is a good material for telescopes because the metal follows air temperature closely, so it won't contibute to tube currents caused by a tube thats too hot or cold.
To get the mirror down to ambient air temperature I use a home made cooling system with a pair of thermoelectric coolers - peltiers. When they are running the mirror can cool by 4 or 5 degrees per hour, much faster than if I just let it cool normally. I make sure that this is switched off about an hour before I start imaging to let the whole mirror stabilise.
The filters I use are Astronomik brand RGBI. They have nice sharp bandpass graphs, so they complement each other nicely. I have been told (don't know if its true or not) that the normal colour filters like the ones you mentioned are not really that good for imaging, but they're ok for visual use.
I have a set of meade colour filters too, but I havent tried using them with the camera.
I captured 700 frames in each of RGB because, at 25fps, that was about how long I had before Jupiters rotation started to spoil the image alignment on its disc. I spent about 1.5 minutes grabbing these frames.
Each colour comes to focus at a slightly different point, probably because of the barlow. I have a motorised focusser (JMI DX1M) which can reset its position individually for each filter and that proved invaluable to getting sharp images in each colour.
I wanted to get a smooth result, so rather than stacking together 700 images and then applying unsharp masks etc I decided to process individual batches of 100, fix each of them up with registax, wavelet filtering, unsharp masks etc, and combine the final 7 in each colour to get a smooth result.
There was a lot of guesswork in this - it's the first time I've tried a batch technique like that, and the 21 runs through registax took most of the morning to do...
Each batch was processed through in Registax, with some wavelet filtering. The image was saved and loaded into Astra Image and sharpened further with lucy-richardon deconvolution and a gentle unsharp mask.
In the end, 7 masters are combined to give the final image for each colour, and then these 3 are recombined to create a colour result. Because I had the images already in Astra Image it was easiest to do it there, but you could probably use Photoshop or some other program.
I'll save this thread and break it down into digestible chunks and meditate on it. I certainly get the general idea, I now need to see how I can apply it to my current equipment. I guess I'll need to start getting some filters. I've been hearing a bit around the place about Astra Image. Guess I'd better download and give it the 30 day trial.
Great descriptions Bird, sounds like a very long and drawn out process, pretty much like most astrophotography, especially deep-space stuff.. I guess that's why this part of the astronomy sport requires such patience, it's really not something for those that want a quick fix.
I'd love it if you could post a pic of your setup Anthony, sounds like a great bit of gear you've got.
Fantastic work bird. That is an exceptionally detailed shot.
I was wondering how long it took to capture the 700 frames and the problem with rotation, thanks for the answer.
Mark Suchting figured my 16" mirror (that I have yet to test). I found him to be really helpful and a thoroughly likeable bloke. I can second the recommendation if anyone out there in Aussie interweb-land needs a mirror.
Very nice work, in fact I think that this is much better than your previous efforts, you are now Wes Higgins rival. Think I might get up early tomorrow and give it a try again.
It might sound like a long process, but it doesn't feel like it. Because I set up at sundown, and don't start imaging until dawn, there's really a lot of time to get everything sorted out - and grab a few hours sleep along the way.
I'll be trying again tonight. Fingers crossed for clear skies - this time I'm going to try a new sequence of grabbing RGBGRGB - 300 frames of each - and the breaking each 300 into 2 batches of 150, stacking the best 100 in each. This gives me the same total number of raw frames as the last time, but means that the colours are sampled closer together.
Oh, and here's a pic of the Beast, just assembled in the back yard...
iceman, no real light pollution - canberra is pretty spread out, and there's lots of trees n stuff around. Not sure how I'd go for deep sky work, but for planets its fine.
The small PC in the instrument case has a wireless lan card, and it feeds temp data about the mirror and tube back to me inside the house, so I can see how it's going. The wireless card isn't quite fast enough to feed video, but in a year or so we'll have wireless firewire at 400Mb or 800Mb, and then I can stay inside :-)
The FL is 1500mm. It's a 250mm mirror, f/6. Not sure if you can see it in the pic here but the top 1/3 of the tube unclamps and comes off for easy transport. That's thanks to a great guy called Gary Mitchell in Sydney. You can see one of the clamps in the picture.
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and thanks again
