Did this in the early hours of this morning, got as much as I could before it disappeared behind the POD dome.
Hope to get a chance to add to it as it's noisy.
Using my new Sky-Watcher Evostar-80ED DS-Pro (I'm selling the Megrez)
Modified Canon DSLR EOS 450D and CLS filter.
12 x 5mins 800 ISO + D,F, DF and B
Processed in DSS and PS CS3
Using the same flattener as the Megrez, I still have distorted corner stars but not quite as bad as the Megrez, so might have another try at getting a spacer.
N.B. Tried to put this on the gallery but it's not playing ball today.
(http://www.caroleastronomy.webspace.virginmedia.com/_wp_generated/wpa2a12bbf_0f.jpg)
It's a good start but, as you say, a bit noisy. The colours look good - especially the main 2 stars.
It looks like the black point has been set a bit low - if you set it less black I think it will look better.
Mark
As Mark has said it's coming along nicely but it needs a lot more subs. Altering the black point will cover up the noise to a degree but you could try some noise reduction on the dark areas instead.
I think the next thing to work on is star bloat, that bright star is a good example. Did it start out that way or as a result of processing? Dewed optics can cause that effect.
Robert
Thanks Mark and Robert. Agree with what you say. Believe it or not I did do some noise reduction, but I'm really struggling with star bloat. Have been given a few ways of reducing star size but always seem to end up with a ring or halo despite feathering. But will take another look at some of the options.
I had dew heaters on so I don't think it was dew although I never actually looked into the lens to double check. I am 99% confident that they were working OK.
Perhaps you would be kind enough to give me a lesson at some point on how to reduce the bloating, using Photoshop.
Since this is hopefully not going to be the final image I won't go too far with re-processing at this stage.
Carole
Sorry Carole I haven't used PS for astronomical images for a while now. I do use it for normal pictures sometimes but they don't usually suffer from star bloat.
Robert
Quotenormal pictures sometimes but they don't usually suffer from star bloat.
:cheesy:
I am sure I'll get the hang of it eventually.
Carole
I'm not a PS user either. Having said that, I did use it yesterday to perform a masked replacement of a star trail in one sub with the equivalent background from another sub.
Mark
Had a go at trying to reduce the bloated stars, I think this is slightly better, but as you can see I get a slight ring around the left star whichever way I try to do it.
(http://gallery.orpington-astronomy.org.uk/albums/userpics/10047/normal_NA_Nebula_12-6-11_12_x_5mins_5_degrees_reduce_stars_Gallery.jpg)
Just guessing, but it looks like you are using whatever process too severely.
It looks as though the process is treating the nebulosity around the star as the star itself, tightening the nebulosity into the star.
Hope that makes sense.
Mick's re-process of his NA Nebula inspired me to have another go at mine.
I think I've got the stars better this time and Pelican shows up better as well.
(http://www.caroleastronomy.webspace.virginmedia.com/_wp_generated/wpc32e4e44_0f.jpg)
Carole
Like the way you've tamed that git of a star :)
QuoteLike the way you've tamed that git of a star
I was sure I tackled the stars the same way last time, but maybe I didn't 'cos it's come out different.
On the basis of your thread and this one, I hope you are not going to take the first process as the one to present for "members images" Mick. :cheesy:
Carole
You'll have to process that star separately to tame it any more. I'm sure I wrote the process down somewhere, I'll see if I can dig it out...
Robert
The fainter nebulosity e.g. Pelican, has come out better but you've lost most of the colour in the 2 brightest stars.
Quoteyou've lost most of the colour in the 2 brightest stars
Yes I noticed that.
But how many re-processes can one thread take?
Carole
Thought you already had that record :lol:
Quote from: Carole
But how many re-processes can one thread take?
It's good to see your progress and everyone learns from it. Getting the processing "right" is one of the most difficult aspects of astrophotography. I put the word "right" in inverted commas because everyone has their own subjective idea of what is right.
I don't use Photoshop myself for processing but I notice there is a new book just out called "Photoshop Astronomy" (reviewed p81 July 2011 Astronomy Now). It may well be of some help.
My own technique tends to be very "purist". I like to process the entire image in exactly the same way. For instance I don't perform operations such as "select stars" because that would imply you are going to treat stars in a different way to the rest of the image. That offends my "purist" instinct. I'm not saying my approach is "right" and others are "wrong" - it's just the way I presently try to do things and I'm currently happy with the results it gives. Maybe further down the line I'll find my approach too limiting and I'll adopt a completely different style of processing.
Mark
OK, got a lot more subs last night. Now a total of 38 x 5mins (3hours 10 mins).
On first inspection this doesn't look too bad, but if you enlarge the image there is strange streaking accross it. I have had this once before and have no idea what is causing it. I stack and process the same way each time.
This one was stacked in DSS in two batches (both from scratch) and there were no streaks on the first batch. I wonder if it's something to do with the double batching.
Any ideas? Have not gone too far with the processing as it seemed pointless in the circumstances. Might have a go at processing in one batch and ignoring the different flats and darks just to see what happens. You can get the larger image from the gallery.
(http://gallery.orpington-astronomy.org.uk/albums/userpics/10047/normal_NA_Nebula_12th___22nd_June_2011_38_x_5mins_800_ISO_~0.jpg)
Carole,
Try processing the second set of subs separately - I think you'll find the problem lies with them. The streaks are caused by the fact that you suffered drift between subs during the acquisition and that your darks are not well matched to the data. The streaks are then caused by the hot pixels (and warm pixels) leaving "trails" during stacking because the darks have not removed them first.
Mark
Hmmm, I wonder then whether it was my efforts to manually dither and perhaps overdid it :cheesy:
Carole