This is Jupiter on 26 Feb with average seeing. I have to point directly over my tin roof to see Jupiter, so maybe that has something to do with how wobbly it was. I used a Bahtinov mask with LiveView to focus, and the diffraction spikes danced around quite a lot. Hmmm. Is that seeing, or some residual tube currents? Anyone know?
I shot ~7,500 frames using a Canon 600d in HD video mode through a Meade LX200-ACF 10" at f/10 (no barlow as yet). Converted to AVI in VirtualDub then aligned/stacked the best 30% and wavelet'd in RS6 (AutoStakkert still spits the dummy with those converted AVIs). Some further modest processing in Gimp: Gamma, etc.
The bright halo is an obvious artifact. If you look very closely, you'll see a couple of others (e.g slight tearing) as a result of (I think) imperfect stacking.
My guess would be that I've over-sharpened and/or under-exposed (if I've read online advice correctly) and maybe used too many align points or otherwise don't have alignment worked out properly (I used 79 manual points placed on "high contrast" details).
I'm open to suggestions. Any advice would be appreciated.
I'm no expert in planetary imaging but I think the ring around the limb is probably due to 2 effects: planet rotation; and or alignment of frames.
The planet rotates ~ 10hrs, very fast for such a large planet, thus the data between the 1st and last frame differ and the processing cannot compensate for this. The only way to negate this effect is to take smaller number.
Successive frame alignment is difficult as the image dances around with currents in the ota and atmosphere. You can tell good nights and a cool ota as the image sits nice and steady in the sensor. Indeed there is a lot of planetary imagers who seeek good locations, like on a small'ish island to obtain best atmospherics.
Your image is real good though don't get me wrong it's a credit and well done.
pretty much Mike covers all these (and more) bases in his how to article.
Not that I know anywhere enough about Astrophotography, I do know you get a lot of heat rising of buildings & rooftops. Maybe try again somewhere with no buildings to shoot over the top of. Good job just the same!
I used to own that exact scope, it took *hours* to cool down, so it could be tube currents. But yeah, rooftops don't help.
How long had it been outside?
I used to own that exact scope, it took *hours* to cool down, so it could be tube currents. But yeah, rooftops don't help.
How long had it been outside?
Hi Peter,
It had been outside for about 2.5 hours by the time I took those shots - I put it out at sunset - but it was summer in SE Qld, around 8.30 - 9pm, so rapidly changing conditions. 2 hours or so has been alright for visual so far, but maybe it needs more for good photography.
My roof is objectionably hot - gets up to near 50 deg C. on a hot sunny day - and holds the heat for many hours. I've been looking at some sort of active cooling for the roof space (e.g. fans) as whirly birds are next to useless (can't move anywhere near enough air).
Have some fantastic details for going flat out at F10, no barlows Bot.
My thinking of the stacking allignment issue is good as details are rather sharp, if the stacking was all over the shop, one would assume the details would be also ?
So, Id assume the ring is from the processing side of things, tube current would effect the whole view, not just the outer limb ? Maybe over sharpened, and/or need more careful selection of the disc with some feathering, i assume you selected the disc seperately, as the background is rather solidly black ?
But yeah, I guess at a processing caper possible ? tho wouldnt bet my left one on it tho, Lol ...
So, Id assume the ring is from the processing side of things, ... Maybe over sharpened, and/or need more careful selection of the disc with some feathering, i assume you selected the disc seperately, as the background is rather solidly black ?
I think it is the sharpening - it brings out the details, but has that effect at the edge. I just ran through some processing a couple of times and saw the halo effect build up more as the sharpening got more aggressive.
I didn't select anything during wavelets or processing in Gimp, so maybe that's something I should do? Would it mean I select the disc of Jupiter, maybe with a small gap to the edge, and sharpen only within? I'm not sure how to do that in Registax (or even if it's possible), but selection in Gimp should be fairly straigtforward.
It had been outside for about 2.5 hours by the time I took those shots - I put it out at sunset - but it was summer in SE Qld, around 8.30 - 9pm, so rapidly changing conditions. 2 hours or so has been alright for visual so far, but maybe it needs more for good photography.
I find that it takes until midnight some days for the conditions to suit imaging. Depends on the day though.
I think it is the sharpening - it brings out the details, but has that effect at the edge. I just ran through some processing a couple of times and saw the halo effect build up more as the sharpening got more aggressive.
I didn't select anything during wavelets or processing in Gimp, so maybe that's something I should do? Would it mean I select the disc of Jupiter, maybe with a small gap to the edge, and sharpen only within? I'm not sure how to do that in Registax (or even if it's possible), but selection in Gimp should be fairly straigtforward.
Im not sure if selecting the planet is the way the experienced guys do it Bot, but its how I do it as you are only working on the good signal within the planets disc, therefore giving more accurate hystograms on the planet - no real need to streach/process the background much.
Yes, Re : Sharpen, tho I only use PShop, still relevant tactic tho
Select the planet, reduce the selection by 5-10 pixels, depend on scale; Feather by 2 or 3 with the 5 pixel reduction, , , or Feather by 4 -6 with the 10 pixel reduction. anyway, prob an un-orthodox method, but works for me for what I do
