Blue rim problem - Processing opinions needed

[[1ponders]]

Well it was lovely last night until I started processing my avies and every single one has come out with this damn blue rim!! I've accentuated it in the pale image to make it more visible. Nothing I do in processing will get rid of it. I'd say it was from my barlow (acro) but the previous nights didn't show this problem.

Any suggestions/opinions on what has caused it or how to get rid of it.

[Dennis]

Hi Paul

Those are fine images. I don't have a solution, but I can say that all my Jupiter’s have a blue crescent, always on the edge that is rotating out of view. Sometimes it also appears on the edge coming into view along with onion rings, so it may be an exposure artifact?

Cheers

Dennis

[davidpretorius]

1. do you have ir/uv filter
2. i get that sometimes if i capture in optimised colour or standard mode. It does not appear in raw mode.
3. do you mind grabbing a quick astra image red, green and blue, and post those as well. blue channel may have been messier than the night before

[[1ponders]]

Ok here is a screen dump of the top left image. As you can see the blue channel is atrocious. I stuck with basically the same settings as the previous night except with a bit more gain and a bit more brightness. Same frame rates exposures, identical equipment.

[asimov]

Yes, I get this too. Bear in mind I was getting it in the refractor & now the C9.25 using the APO barlow & IR/UV cut filter. I can get most of it out by manual tweaking rather than let registax auto guesstimate the RGB shift. The rest can be removed by tweaking in photoshop or whatever your using.

Some nights are worse than others which tells one it's to do with atmospheric conditions.

[[1ponders]]

It could be Asi, but I've a feeling its either a misalignment problem or a capture settings problem.

This one was taken during the previous imaging session at the same time of night under pretty much identical conditions, maybe a bit more moisture in the air but temp and wind (zero) seeing, transparency all about the same. The only thing that changed were my settings and my mount (I used my GM-8). Apart from the settings the only other difference was that I had to make centering adjustments during some of the captures, but they fairly minor and at 0.3X guide rate

You can definately see misalignment in this image and the corresponding Blue channel in Astra Image. It just seems to be the blue channel stuffing things up.

[asimov]

I see it on my laptop before I even start capturing. :shrug: Another one of those 'combination problems' like the onion rings perhaps? :(

[[1ponders]]

That's the thing Asi, apart from some chromatic aberation from the barlow I don't see anything specfic. Sometimes I can see when onion rings are likely to result after processing and can adjust for it, but not this.

These are screen dumps of single frames from each nights capture. Not a lot of difference in them except one is slightly brighter than the other.

[asimov]

I'll be interested in reading the varying opinions & 'fixes' for this problem in this thread from the processing guru's.

[iceman]

As you can see, the blue channel is very messy, and is the one most affected by atmospheric turbulence and seeing. The seeing looks like it was pretty good judging by your images, but that blue frame is still horrible so there had to be something in the air.

I think that's all the problem is, just a bad night with turbulence and the blue channel is not aligning properly.

As DP asked, are you using an IR blocking filter? If you're not, I'd suggest using one, because I saw this effect most (especially on Mars) when I tried the with/without IR blocking filter. The filter helps stop the blue wavelength bleeding into the other channels (at least, that's my understanding).

[[1ponders]]

No I'm not using an IR filter, the only one I have is that lovely blue tinted one (you remember the one Mike ;) ). I'll give it a go and see if I can process the blue tint out.

[iceman]

I wouldn't bother. Spend $120 and get a proper one.

[[1ponders]]

Hmmmm :confuse3: bit of a toss up. New, bigger HDD to keep the growing mountain of Avies til I get to process them, or a new IR to make the Avies worthwhile keeping. Tough call.

New HDD this month I think. The last couple of nights have been ridiculus trying to juggle space on computers :rolleyes:

[iceman]

yeh, it's a tough one. But don't bother using the blue IR filter.. you'll ruin some avi's taken in great seeing cause you won't be able to get the blue out :)

Keep capturing without for now, as it's not a big a problem on Jupiter/Saturn as it is for Mars. Make sure you get one soon though!

[davidpretorius]

yes, those blue channels are messy. it is such a pain in the butt. There is no way I can tell at the capture how it is going to turn out. I would have 8+ seeing, the avis look exactly the same, but split different avis after stacking and the blue is different.

raw colour mode allows a tighter finish to the blue channel i have found.

and get that ir filter. It is my next purchase

[asimov]

As I mentioned, I'm using the IR/UV cut but doesn't solve the problem totally. I will do a side by side with & without the filter to see the results soon. Sheesh! Another test to do! Never ending isn't it!? :)