Can anyone give me advice.Ive been imaging jupiter & when i get to the wavelets in registax & slowly adjust the bottom 3 sliders, im getting onion rings around the planets periphery. Any advice?Not enough gain?
Thanks.
It's typically caused by underexposure, so yes, more gain and more gamma.
For Jupiter, I use around 40-50% gain and 40-50% gamma. I get no onion rings when this happens.
As a last resort, you can do your processing in PixInSight which allows you to mask out the edge of the planet so the wavelets are only applied to the middle area.
I'm not convinced we've got to the bottom of this onion ring problem yet. One of my Jupiters I posted this morning was with zero gamma & zero gain. The only thing I did differently was to stack 3 filters: contrast booster/IR/UV cut/fringe killer. I was willing to go along with everyone on the conclusion that it was caused by under exposure, but now I'm unsure!
Sorry to throw the cat amongst the pidgeons here, but I'm really trying to come to a definite conclusion on these rotten onion rings.
Finally, the onion ring discussion we had to have...
I know Mike's convinced that this is due to under-exposure, but I have to confess to being far less sure. Really need a scientific approach trialling a wide range of settings and exposures and under different conditions to get to grips with this. It may be that under-exposure is a contributing factor, but Asi and I both think that undulating planet edge/shape due to poor seeing - when it can't be filtered out with quality (and the quality setting in registax alone can't do it), alignment box placement or culled manually, is certainly contributing.
One thing I do know is that I have Jupiter shots that Do show onion rings when they were captured with medium gain/gamma and light meter almost at the top of the K3CCD tools scale (e.g. >220), and yet others with much reduced gain/gamma settings so the light meter is reading 170-180 which Don't show onion rings? This strongly suggests to me that exposure can only be part of the puzzle.
Anyone with clear skies often enough to run some tests
I have clear skies I'll be trying to conduct some more tests, maybe on saturn, as it rises earlier. (I get onions on Saturn just as much as Jupiter) I will record the conditions/settings/everything/AVI taken at very little gamma/gain, & one at the 'recommended dosage' both with & without filters? Or leave the filters out of the equation? Better I leave the filters out I think.
Thanks a lot guys for your input.Ive got clear skies tonight so I'll try a few different settings.Thing is, when Im setting the gain in K3CCD, I slide it down until i see some kind of detail on the planets disk.It just looks too bright any higher.Usually this equates to about 40-45%.Tonight I'll go higher & bump up the gamma.
By the way, had hamburgers with onions rings for tea
Lol. My wife cooks deep-fried battered onion rings on occasion...yummy!...Oops! off topic!
Now then, as I was going to say.....Davo, If I posted all my images that were NOT taken in somewhat 'crap & undulating' conditions, guess how many images I would have posted sinse owning the toucam?...TWO!
DP - do you focus at those gain levels (50-80)? It would be impossible with my setup to see anything to focus on, it would be nothing but grain. I'm beginning to wonder if the neximage is the same as the toucam. I have imaged occasionally with gain up to 50%, but only after focussing on the planet with gain wound back...
it's complete cloud tonight as it has been for weeks, but I've decided to setup anyway and hope...
Hmmm, it's all very interesting, isn't it? Just finished stacking an AVI of jupiter taken just after the two I posted this morning, taken at 80% gamma 55% gain {1/33 sec exposure because it was way too bright to image, normally it would be at 1/25th with less gain & gamma} complete with onion rings....
Hmmm, it's all very interesting, isn't it? Just finished stacking an AVI of jupiter taken just after the two I posted this morning, taken at 80% gamma 55% gain {1/33 sec exposure because it was way too bright to image, normally it would be at 1/25th with less gain & gamma} complete with onion rings....
robin, take note of the white level meter in K3CCD when you're about to start capturing. The image should be properly exposed, with no areas overexposed. So the white meter should be between 180-230 on most objects. I find that gives me the best range of exposure without onion rings.
Rob, as per DP, I focus with lower gain and gamma so there's higher contrast on the features to give your eyeball something to focus on. For Jupiter, I try and use a moon to focus on if the seeing is good. If the seeing is no good, it's much more difficult to focus on a dancing distorting moon.
That was the problem i had reconciling having my gain higher Mike.Some of the areas were overexposed so i bump the gain down which gives a nice looking, well exposed disk but then Im finding those onion rings start to rear their ugly rings from not having the gain higher.
That was the problem i had reconciling having my gain higher Mike.Some of the areas were overexposed so i bump the gain down which gives a nice looking, well exposed disk but then Im finding those onion rings start to rear their ugly rings from not having the gain higher.
overexposed on the screen during capture or after stackinging in registax.?
make sure histostretch is not turned on during stacking.
don't go for nice looking whilst capturing. you can have the image as grainy as hell during capture and that grain will disappear upon stacking.
here is dennis avi from that fantastic night on 4th feb. this is the first step of registax, image is very grainy and bright, but all of this can be taken out after.
in reference to this first one, where do people's capture preview screen relate? brighter, dimmer???
2nd image is the create reference on 50 of 480 frames, no wavelets. as you can see the noise has gone. no histostrech, just simple optimise / stacking.
3rd on is a finished stack of all 480 frames
4th is a finished product with rbg align and soft wavelets.
ps, dennis's data is like working with silk or viewing thru a 200mm takahashi refractor. (don't worry stu isn't imaging yet, so won't look at this thread and spam this tread with drool. no doubt he will sense that something was said in a thread, but will tear his hair out looking for it!!!)
Tests done last night: 9/03/06 The first image: taken using 80% gamma 55% gain & 35% brightness. 1/33rd sec exposure @ 5FPS 600 frames captured/120 stacked.
The second image: zero gamma zero gain 100% brightness. 1/25th sec exposure @ 5FPS 600 frames captured/120 stacked.
Identical heavy waveletts used on both images. Identical processing in picture publisher (unsharp mask) Identical noise reduction/sharpening in neatimage.
6" refractor & toucam. Please ignore image quality, shot in terrible seeing conditions for test purposes only.
This strongly suggests to me that exposure can only be part of the puzzle.
I'll be trying to conduct some more tests, maybe on saturn, as it rises earlier. (I get onions on Saturn just as much as Jupiter) I will record the conditions/settings/everything/AVI taken at very little gamma/gain, & one at the 'recommended dosage' both with & without filters? Or leave the filters out of the equation? Better I leave the filters out I think.
