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Aaargh!

This is a single sub (of 65) from last night's shoot...

post-23222-0-49351600-1340118097_thumb.p

So I thought to myself "WOW! I'm gonna get a FABULOUS result from the stacker". Instead, I got THIS:-

post-23222-0-28473800-1340117964_thumb.p

Somehow that doesn't look quite right. Any ideas for settings? Or should I be using a different program for this? I'd really appreciate the help.

Oh, that's no darks etc and no processing on either image.

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Not sure what to suggest , looks to be more there than my 20s ISO 800 subs from the other night ,

I watched this tutorial on DSS and the guy did say that sometimes the stacked image looks really ropey but not to worry because all the data's there , it just need dragging out ,

Hope this is of some use mate ,

Steve.

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Um, the process throughout? Don't understand the question, sorry. The only thing I used was deep sky stacker. I'm wondering if it has saved all the tweaks I was using for M13 the other day and I can't seem to reset to some "default" so that I can start again.

I'll take a look at that tutorial shortly.

In the meantime I gave the same subs to Registax; and though it took me a while to learn the right settings to get one star per place instead of thirty I always had a good nebula. So here's the untouched output from Registax...

post-23222-0-44977700-1340124681_thumb.p

Bum! That's only a stack of 2 !! Hmm... how to get it to stack a few more... think.gif

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Just tried that RegiStar and even it could only stack two images. I went back and had a good look at what DSS was (not) doing and it turns out that the histograms, instead of being nice solid mountain peaks for each colour were just three or four single spikes following what sort of shape OUGHT to be there.

I reckon that when my camera tried to save RAW and JPG versions of each shot it totally messed them up. So much for THAT option. Pah!

Just to prove my point to myself I handed RegiStar the subs from my M13 and it worked just fine. Leaves me to do a lot of post production stuff with levels and curves which my last attempt with DSS didn't need but yes it's a nice program. At $149 it's going to have to wait until I win the lottery :)

A quick and dirty play, though there's some noise gives...

post-23222-0-76838200-1340132423_thumb.p

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Pretty , bit more orange and i might recognise it .

$149 , I think i'll leave that alone too... :p

Going for some W/A shots around Cygnus tonight I think , OIII in place and see if I can pick out something of the Veil , Milky Way was quite prominent the other night so here's hoping.

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I meant, how have you stacked it on DSS. Have you played with any of the curves at the end? I wonder if you may have stretched it too far?

Oh right. Nope, mostly used defaults or recommended that was on offer and that result is a raw untouched output. The thing was, given the apparent quality of the images I saw on the LCD screen I thought I was in for a cracker. Post #6 here explains why.

I deliberately handed it a set of median subs too - the ones that got mid range scores on registration and it was worse! Of the 65 subs I had PSP would only load the first 28 and point blank refused the rest - both the jpg and the raw.

DSS, RegiStax and the trial Regi Star all failed to make anything of them no matter what I did.

Anyway, possible clear sky here from midnight and I'll be doing jpg's ONLY because from my M13 the other night I KNOW they'll work. Unless, of course, something in my camera has failed.

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<sigh>

Started out as a good viewing night, so got a load of ten second subs. Then went for (and got) some twenty second ones, but not many because the sky started to get hazy and the dew fall started so I was wiping the secondary between shots.

My ten second subs have been a worse disaster than yesterdays. So cropped the twenty second images with one star always centred then handed them over.

Nine images like this:-

post-23222-0-47858200-1340177231_thumb.j

DSS hated them but I eventually got this. It did a good job on the stars but seemed to treat the nebula as a large collection of faint stars!

post-23222-0-26560300-1340177248_thumb.p

So I let Registax have a go. Nicer nebula, rubbish star alignment:-

post-23222-0-46237300-1340177279_thumb.j

In the end I had a play with the frame shown and got this...

post-23222-0-45131800-1340177308_thumb.p

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Unfortunately my eye can't see as much as my camera can. (The fainter stars in those images are Mag 15) And my drawing skills are not exactly fabulous either. So the end result would still be pants :)

OK... for DSS how many stars is "not enough"?

I counted 47 easy ones in the subs - so how do I get DSS to accept them? One way I've found of keeping track of how many stars are really in there is to equalise the histogram. No good for imaging purposes (yet) but the more of the stars you can keep, even when you can't see them initially, the better. i reckon :)

post-23222-0-16275300-1340192530_thumb.j

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So... my challenge to myself this afternoon was to get all those stars on a proper dark clean sky (don't worry about the nebula - I'll work on that on another layer.

From that first jpg which I equalised in the previous post I got the image to the right, and of the left is the equivalent Stellarium view. So I've found a possible eclipsing binary and at least two stars with fairly hefty proper motion. The highlighted star in each bit is the faintest that I'm sure of. Not bad considering I was looking over a major city...

post-23222-0-29772100-1340203894_thumb.j

Anybody want to count all the stars? :)*

post-23222-0-33236100-1340204389_thumb.j

The next challenge will be to get a layer with a good nebula now! Eek!!

* I make it a possible 121

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Taking the sting out the star layer and pasting it over the top of a layer where I worked on the nebula, I have...

post-23222-0-54144600-1340219624_thumb.j

Right, that was a practice run :)

Need to go find my best sub for stars and my best sub for nebula and get to work! :)

Maybe tomorrow.

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Oh well... wrong image above, lost too many stars in that one.

post-23222-0-40285000-1340339270_thumb.p

Here's the equivalent view in Stellarium...

post-23222-0-72682900-1340344853_thumb.p

Considering that mine is made up of subs that barely total one minute I'm hoping that in a good sky with lots of subs I can do a little better.

Even so, with the eye of faith you can just pick out the faintest hints of the stars within (behind/in front of) the nebula itself.

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DSS needs to detect a minimum of 8 stars on each sub or it will not stack them (it tells you how many it has detected on the list of images at the bottom of the screen). Looking at your original image of a single sub I suspect it is struggling to detect that many with the default settings.

NigelM

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I sometimes find DSS won't stack if there is elongation of stars or smear from factors such as wind (or a minor bump). In your first post you mention not using flats or darks - I would definitely include these in any image processing, and you'll notice huge improvement and have an easier time with levels, curves, and unsharp masking. Also, make sure to only shoot in RAW format - your image quality will be SO much better than crappy jpgs. If you can manage longer subs, you'll find DSS likes them better, too. I used to image on a homemade EQ platform and took 15-45sec prime focus subs. DSS usually didn't like about 1/3 or more. Recently, I have been imaging on a CGEM with 3 to 9 min subs, and only one sub has been rejected out of the 4-5 DSOs I have practiced on (with an old unmodded Canon 300D).

The last image you posted looks really good, BTW. The colors are outstanding and close to the Stellarium image.

Happy Imaging

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Hi, :)

Thanks for all that.

DSS certainly seems to do a better job with raw rather than jpg. I've got some stock bias now. I did do some flats but I'll need to re-do them; two of the primary mirror clips weren't just on a light touch - they were loose and rattling! So everything is re-aligned and re-collimated and, since this a flex dob - I took the opportunity to use a very soft camel hair brush to remove some dust.

I've been getting better at alignment and so am suffering less drift now. Plus I'm currently working on balancing for the weight of my DSLR.

As for darks... they don't really help, and using noise reduction in DSS certainly doesn't. This because the Nikon has built in noise removal. I have found that if I turn it off and do a 30 second sub I get three stars in a trail. With noise reduction on I get a single star. So that seems to be the way to go. I forgot to change ISO from the 3200 that I'd used for those 10 second subs last night on a test between clouds and got very noisy images - so I'll be trying 800 and may even have to drop to 400.

Now that I'm a whole lot faster and more accurate getting started and aligned than I was to start with ( a whole ten viewing nights ago) I'm hoping to knock out 80 - 100 30 second subs and might have 30+ really good ones to stack.

First target will be to revisit M13, and then by the time that's done I'll hit M57 because it'll be higher in my light polluted sky.

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