Hi all,
I'm tossing this to all you pros, cause I'm at my wits end.
After a fabulous session last night, I accumulated what I thought was enough data to produce a pretty good image, not so.
The nebulosity seems fine, nice and smooth, but the back ground, the dusty areas, are noisy and streaky.
Is it just lack of data???
This is a 100% crop, 3hrs of 5min subs @ iso800.
I'm out again tonight and will change the setting to iso 400, see if that makes a difference. Might try using ICNR too.
3 hours and still that noise? Could well be excessive heat noise. Or using darks that were at the wrong temp. Didn't you take your darks before your lights last night? Definitely give ICNR a go. Its a pita I know but when you have trouble matching your darks then its the easiest way to go.
jjj the neb looks great.
Obviously 3 hours has helped the Signal to Noise Ratio and produced lovely detail in the wisps.
If you're going to do 3+ hours then don't go above ISO 400.
I never go over ISO 400 even in winter.
Also I always try and get as many dark frames as I can squeeze in, especially in summer.
Those wisps look great, mind posting the full image Need something to drool over. Plus the info on what u used hey.
I'm not even bothering to image atm so hot here, take my hat off to u for your dedication, or is it obsession ! lol
obsession is the word.
I haven't done any layering on the full image, so the trap is blown to smithereens. Not a pretty sight. But you asked for it.
I've cropped, resized and toned down the whole image to try to hide the flaws.
swed80
heq5pro
canon 20d
guided using qhy5
3hrs of 5 min subs, darks taken
stacked in dss
processed in cs3
Ok, I'll put last night's effort in the vault ( I'll try to work some "Zone" magic on it later ) and start anew tonight.
iso 400 icnr on.
wish me luck
I'll be very interested to see who the 2 nights compare Jeanette. I've never really had the luxury of two consecutive dark sky nights to play with M42.
p.s. I wonder if it might be possible to split the pic into Luminosity/Hue/Sat layers, then run heavy noise reduction on the chrominance info only in the fainter dust areas?
I'll be very interested to see who the 2 nights compare Jeanette. I've never really had the luxury of two consecutive dark sky nights to play with M42.
LOL I'm living the dream Rob. The only problem is, when you wake up in the morning you're still living in a small town.
Here is a quick and dirty reprocess to “try” to remove some of the colour noise. You have some good data there and a nice image scale too! My effort doesn’t really fix all of the issues, but it does show what Noel Carboni actions can do in the hands of a beginner!
I am sorry I can't be more help but it does look like maybe thermal noise. In hot weather and particularly at night when the temprature is changing it is worth doing lights and darks together in groups of say 3 or 4 images then dark subtract with coresponding frames.
Thanks Dennis. I have the actions too, just haven't learned how to use them yet. Same with the "zone".
I'll be at my leisure soon to take my time and see what they can do.
You've done really well there JJJ not often u see all that dark neb stuff, and this is your poor version ! What's it going to look like when u get more data is only going to be Better
How dark are your skies there ?
Considering that I live in town, I'm very lucky that my skies are still fairly dark.
Stars to the horizon, and when in season, m31 is visable.
Wish I didn't have this darn street light on the corner though, but if I take care setting up it doesn't bother me too much.
My vote is thermal noise too. Can Isggest a solution if you dont want to delete the data. Assume you're using PS. It wont be as good as starting weith no noise but it might give you something.
Duplicate image -> on new image run whatever noise reduction filter you like (Carbonis, noise ninja etc etc) or use the Filter -> Dust and Scratches in PS and set it at about 2 pixels (it is pretty harsh so play around with settings (or even Median filter it I havent tried that) - note that now you have lost a fair bit of detail but the main neb in your image doesnt look too bad so use that but again.
On the noise filtered image select all (Ctrl A) and copy (Ctrl C) then set focus to the original noisy image and paste the noise filtered image in as a new layer - you will see the filtered image (make sure you do - you want that to have focus) then select Layer -> Layer Mask -> Hide All and you should now only see the noisy image. Now select the paintbrush and select a suitable brush size (top left) and paint in where the noisiest stuff is. You are painting aaway the noisy image and letting the filtered image at the back come through. Limit painting to background otherwise you lose detail. Yoou could change the opacity of the brush near the edge when you want stop painting - (beside the brush size) by palying around you might be able to blend the two pretty well (Again alternatively runa Gaussian Blur of the Layer mask to assist in blending) . When happy select Layer -> Flatten Image.
I did a strip on the right hand side of your image (still looks pretty crappy but)to show what I mean.
Hope this helps now or in the future (with maybe a bit less noise). Saves running a really strong noise filter on your whole image and losing detail.
Here's my first repro.
Again, apologies for the trap. I've done no layering.
This is an exercise in repairing an image.
I used some functions from Paint Shop, clarify and histogram adjustment, and went back to cs3 for curves.
I refrained from stretching the data too far this time.
![[1ponders]'s Avatar](../vbiis/customavatars/avatar45_9.gif){kind=avatar}
Need something to drool over. Plus the info on what u used hey.
