Last shot for awhile... Promise! M20

[Robby]

Hi all,
This will be my last shot for awhile. You'll be sick of my shots by now!
Last night I wanted to go longer than ever on M20. I've actaully yet to really nail this nebula.
So I setup for 30x4min exposures!! Thats 120mins of total exposure.
Came out ok, but not a great deal of improvement over shots half as long.
Although the processing was much easier due to the extra noise reduction after stacking so many.
http://www.star-mate.com/temp/M20.htm

Cheers

[asimov]

Oh........What can I say Robby... What a totally MARVELLOUS picture!!!!!!! Please DONT stop posting pics like this?!? How could one get sick of seeing this sort of thing? Well done mate! Keep them coming! Do you do requests?? LOL

[Robby]

You hum it & I'll play it...

Thanks for your nice comments! Always appreciated!

[asimov]

Mate, I gotta repeat what I just said!! I LOVE that shot man! WOW!

[asimov]

In all seriousness, It's the best shot of M20 I've ever seen with a scope such as yours....And you reckon you haven't nailed it yet!? Geez....Please nail it then, by all means! That's my request!

[Robby]

I meant that I hadn't nailed it until now. Well, I think I've almost nailed it.. There are still a couple of things with it that needs work, but generally it came out well. Just don't look too close to the edge of the field...! Bit of coma there from the focal reducer. :(
Cheers

[beren]

Very impressive , diffraction spikes look great , what ISO was it did you go lower then usal with the greater number of frames to stack ......finding with the D70 going over 800 results in images difficult to tweak in processing

[ving]

how anyone could be not happy with that i dont know... brilliant! :D

[seeker372011]

Keep them coming Robbie..don't stop now you have it humming along nicely. No one is bored!

Have I got it right--you stacked 30 shots each four minutes exposure? or was it the other way, 4 thirty minute exposures

If it is the first... man, you must have some grunt in your PC-I'm assuming these are all RAW files-each say 6 or 7 meg in size? What software did you use ?

[gbeal]

Coma? What coma? Come on, you are getting too fussy. Can't complain about this one, nore the Grus trio, awesome.

[Robby]

Thanks guys! Great to get your feedback. :)

Beren, I have settled on ISO800. I was using ISO1600, but the extra noise wasn't worth the increased sensitivity. What's an extra minute of exposure anyway!

Seeker, Yep, it's 30x 4min shots. I'll let you into a little secret... I actually shoot in jpeg :ashamed: I have found RAW too cumbersome, and gave little or no advantage. Although I have come along way since making the switch, so should try RAW again, for comparison. Software I use is Photoshop. It was quite an effort to dark subtract, align, & stack in Photoshop, but we got there... Woudn't want to do it every day. Really should think about getting some specific calibration software. One day.

Gary, Coma is there, particularly in the lower right corner. Bit annoying, but probably only to me!! :) Am pretty happy with it really.

Cheers

[beren]

Robby when you use PS how do you do the dark subtraction ?

[Robby]

Image on one layer, dark on another. Change blend mode to difference. Flatten and save. Repeat will all images :D. Done!
Cheers

[beren]

O"boy thats some work ....just experimented with 8 frames before {taken through the D70 with the inbuilt noise reduction on} and did what i think is right
1.open 2 images select all, copy , paste
2.select difference,use move tool to align
3.select normal set opacity to 50%
4.save etcetc to get 4 frames and co forth until one remains
So you layered etc all your single images with a dark frame and then stacked them after like the method i tried to explain......?
Cheers

[Robby]

Yep that's pretty much it. I do dark frame on every image first. Then stack 10 at a time using this method. The opacity of each lay is reduced by 1/x for each layer.
Layer1 = 100%
Layer2 = 50%
Layer3 = 33%
Layer4 = 25% etc....
So with the 30 I ended up with 3 images after doing 3 seperate 10 stacks. Then stack those 3. Done :) I know there are easier ways, but they cost money, which I don't have much of at the moment :(.. Darn tax man!
Cheers

[beren]

Cheers Robby apppreciate the explanation , a lot of work has gone into this great image well done

ps:with the dark frame is it like one exposure at the end of the session with the cap on the scope on or itself a stack of many

[asimov]

Robby...Have I told you I LOVE that shot mate!???:rofl: It's now my computers wall-paper.:thumbsup:

[Robby]

Auw shucks!! :ashamed:
If yo want a higher res shot you can get it here..
http://www.star-mate.com/temp/M20HR.jpg It's 1.8M though.
Cheers

[asimov]

Thanks Robbie! :thumbsup:

[Striker]

Robby......I love the shot...very impresive mate...well done.

[atalas]

Oh you mean you need a rest after that shot ! now I get It :doh:

Great shot Robby ! one of many from you.

Louie :thumbsup:

[astro-angel]

Awesome shot robbie.....but now im sad cause i want my camera:innocent:

[tornado33]

Great shot, Robby
Dont stop taking pics and posting them here :)
The weather in Newcastle has been great last few weeks, only the odd night clouded out, so ive been gathering as many photons with my scope and camera as I can. Im addicted to astro imaging especially as its possible to image objects too faint to see with a scope twice the size :)
Keep up the photon catching!
Scott

[asimov]

Gee Scott. I would never have figured out you were addicted to astrophotography! :rofl: :D

Keep up the great work mate! love your pics! :thumbsup:

[ErwinvdVelden]

Robby,

Iris written by Christian Buil can do a whole range of dark frame subtraction straight from the RAW's and it is for free.

http://www.astrosurf.org/buil/us/iris/iris.htm

Prepare for quiet a deep dig into the manual, if you have questions however, feel free to ask me.

Cheers,

[Robby]

Thanks Erwin,
I have tried (& failed) with Iris. It's not for dummies like me! I notice that it has a new version. I wonder in the UI has improved?
Thanks for the link!
Cheers

[ErwinvdVelden]

Hi Robby,

A few items were added to the menus but even more items were added to the command list.


Cheers,