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PostPosted: Sat Sep 11, 2010 5:38 pm 
What is your preferred "routine" when you get to post-processing?
I can get somewhat decent results, but it requires a lot of trial-and-error on my part to get something reasonable.

Here are my latest efforts in the Lagoon-Triffid-M22 area...

Image
ISO-800, 100 5 sec. exposures, 50mm focal length, F/4.5

Image
ISO-1600, 100 5 sec. exposures, 100mm focal length, F/4.5

After I finish the stacking in DeepSkyStacker, I have to take the resulting .TIF files into Iris to begin post-processing. I haven't a clue on how to post in DSS yet, and both of my PhotoShop programs (CS3 & Elements 6) only show a black shot, with a few of the brightest stars, that I can't seem to do anythg useful with. After tweaking a few things in Iris (white balance, dynamic stretching,etc.) and saving it as a .JPG, I can then get it finalized OK (more or less) in PS.
It just seems that I'm really taking the long way around, so I'm looking for suggestions.:)

Here are the original .TIF file results I got from DSS for the above pics. Feel free to download them and see what kind of results you get.
It'll be interesting to see what someone who knows what they're doing can pull out of them.
http://www.mediafire.com/file/9hyrlk28a78bhg2/NightSky3.TIF
http://www.mediafire.com/file/666k54t5ua2pwds/nightsky4.TIF

Floyd.


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PostPosted: Sun Sep 26, 2010 6:00 pm 
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I think the biggest improvement you can make is increasing the length of your subs beyond 5 secs. That way each sub will be capturing more detail and when stacked this will help.

I, like you, stack in DSS and also tweak before saving a TIFF (with the tweaks applied) and finishing off in PS.

Try looking at this link for DSS help:

http://deepskystacker.free.fr/english/userguide.htm#processingtab

HTH

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PostPosted: Mon Sep 27, 2010 8:55 pm 
Digz-
I agree with you on the longer subs - the problem is, however, that I don't have a tracking mount yet.
(Immediately puts the Barndoor Mount at the top of his to-do list)
And...
Thanks for that link. I'll give it a more thorough readthrough next time I do some stacking. I might even re-load the .TIFs in DSS and fiddle around with them a bit.

Since I originally posted this, however, I found out about using the LAB colorspace (Luminance, A-channel, B-channel) in PS.
LINK (Second half of the page)

I still have to set the beginning white balance in Iris (it's just easier for me), but using the LAB method really seems to save a lot of time and effort.

Floyd.


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PostPosted: Tue Sep 28, 2010 12:45 pm 
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Without tracking mount you could use longer exposures than 5s :wink:
30s with the wide angle lens is very good possible, I used 40s on 27mm (35mm eq.) without startrails.

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PostPosted: Tue Sep 28, 2010 5:43 pm 
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Thats a good link, its been book marked and Ill give it ago when I reprocess some of my images at the weekend :)

A barn-door should be a good device that can be home made to give you a simple and easy tracking platform.

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PostPosted: Tue Sep 28, 2010 7:05 pm 
Ruben-
That's interesting to know :)
If the seeing is good this weekend, I'll probably try my 14-42mm kit lens at a couple of different focal lengths and see how far I can push it before I get trailing (the camera does up to 60sec.).
It'll be nice, if it works, to not to need to take 100 subs when 20-25 will get a better result :D

Digz-
The barndoor mount is my only choice for tracking at the moment - all of the alternatives are way out of my price range :(. My biggest hold-up has been finding a suitable 1 RPM motor to drive it for long subs at higher focal lengths.

Floyd.


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PostPosted: Tue Sep 28, 2010 7:17 pm 
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Set the lens @ 14mm f/3,5 and 1600 ISO, 35s and shoot. Make as many photos as you can (incl Dark Frames).
Then, stack them in DSS.

Try to set your camera at the Milkyway.

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PostPosted: Wed Sep 29, 2010 7:28 am 
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Floyd, try this site:

http://www.scopesnskies.com/AstroBoot they might have what your after for your barn door. At the top of the page there is an EQ RA Motor which may be suitable?

HTH

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PostPosted: Sun Oct 03, 2010 12:25 pm 
Ruben-
Took your suggestion Fri. night...
Started the test at 14mm F/3.5 30sec. - not terrible, but still had some trailing.
Bumped it down to 25sec. - still some minor trailing, but probably acceptable.
Then I tried 20sec. - if there was any trailing, I couldn't see it :). Looks like I found the "sweet spot" for this lens.

I did run into one problem, however... my lens has some obvious vignetting at the 14mm setting. Probably nothing I can do about it unless I replace it with a prime. Such is life.

Here's what I ended up with:

Image
40 subs (32 used by DSS)@ 14mm, F/3.5, 20sec. ea.
Bright star near the center appears to be Altair, with Vega in the upper right corner (to give an idea of my target area)

The corners are a little "off" due to having to use Iris for gradient removal - had some trouble with the flats this time, for some reason, and the corners ended up nearly blown out on the DSS result.
Otherwise, a very easy post-processing, since I figured out that some of my settings in DSS were causing me more work than what was needed :oops:
It had to do with my settings in the RAW section (Debayering setting was wrong and auto white-balance wasn't set, IIRC) so it was a case of "garbage in - garbage out".

And Digz-
Thanks for the link- looks like a good site for odds-n-ends :)
Unfortunately, I think that the motor listed there is a little much for my purposes.
Right now, I'm leaning towards using a clock motor, if the torque required to turn the bolt on the barndoor isn't too much.
I'll keep checking that site, though - looks like they get new stuff on a regular basis, so something usable may pop up.

Floyd.


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PostPosted: Sun Oct 03, 2010 1:44 pm 
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Greta effort, clearly see the milky way starting to appear. Im surprised you could only get upto 20s at 14mm as Im sure I used to get away with at least 30s at 50mm before I had my mount.

If you now stop the aperture down so you are using the sweet spot here you can them increase the shutter speed accordingly (assuming you can use the bulb setting) this will ensure the stars are sharper.

There is something really weird happening at the edges - almost looks like a bit of rotation and DSS not doing a good job of stacking? Or was this was IRIS did?

How did you take your flats? I had the same problem with my flats which seemed to make the edges all washed out.

I just noticed you posted a link to your original images above, Ill have a play with them and post the results if you dont mind?

Glad the link was useful, Astroboot seem to be an Aladdin's cave of astro stuff.

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PostPosted: Sun Oct 03, 2010 1:56 pm 
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When I use DSS with photos that arent tracked, I got those vignetting too.

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PostPosted: Mon Oct 04, 2010 5:48 pm 
Digz-
Have at it, friend :)
Be advised, though - those were done before I got my DSS settings straightened out, so the white-balance is way off.

I took this last batch of flats using my LCD monitor set to a white screen (opened "Notepad") since I neglected to take them beforehand :oops:
I normally take them with a white plastic bag rubberbanded over the objective. I honestly think that it wouldn't make much of a difference in this case due to my lens - the vignetting disappears as I move it away from 14mm to its max. of 45mm (I think it's gone at about 25mm or so).

The corners were caused by Iris removing the unsightly white gradients. I'm not faulting the program, since it didn't have a good starting point.
I may try another set of flats with a little less vignetting in the corners - I just won't tell DSS that they were taken at a different focal length :wink:

As to the exposure times - I forgot to put in that they were taken at ISO-1600. If I would have done 800, or even 400, I could probably have taken much longer subs.
I'll have to try it again with a different aperture, as you suggested. Using THIS (DPReview) chart of my lens, it looks like F/4.0 will give a slight increase in center sharpness area at the 14mm mark without losing anything on the rest of the frame. F/5.6 and F/8.0 don't look too bad either, but I'll probably start with F/4.0.

Floyd.


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PostPosted: Mon Oct 04, 2010 5:57 pm 
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Hi Floyd, yeah I gave it a go and didnt get very far:

Image

Brought out some detail but also brought out some banding and noise as well.

I took my flats in the same manner which is fine as long as you dont hit a shutter speed equal to the screen refresh rate. One thing I did learn is that the aperture must not change at all as this will effect the vignetting! Something which did change when I took my flats. I would imagine change the focal length will give the same problem but its worth a try to experiment.

Yeah, try stopping down and increasing the sub length and see what happens. I look forward to the results :)

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PostPosted: Mon Oct 04, 2010 6:46 pm 
Digz-
Heck - looks better than what I got from it! :lol:
Just did a quick test of the focal length/vignetting thing (gotta work tonight, so I can't give it a full go yet) and the vignetting is gone at 25mm using the same technique as the previous flats. There's still a hint at 18mm, and a bit more (but less than at 14mm) at 16mm. When I get a chance later this week, I'll run a couple more stacks of this past weekend's subs. I'll probably start with the 16mm flats, and if the corners are still blown out, I'll run one with the 18mm.
I -did- do a run with no flats but the corners were noticably dark, so I figure I need something to correct it.

Ah, the joys of the learning curve... :lol:

Floyd.


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PostPosted: Mon Oct 04, 2010 6:55 pm 
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Glad you like it.

I think the point of flats is to record the vignetting at a given focal length and aperture that corresponds to your subs, so DSS can then counteract this.

What I found with my flats (because the aperture changed) when I edited it was that it showed vignetting that was very asymmetrical and as a result the resultant DSS stack was lightened in the same asymmetrical way.

I wouldnt be surprised if using flats at different focal length doesnt work but heck its worth experimenting with :)

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