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At last, a Jupiter I'm happy to share

rwg

By rwg
in Imaging - Planetary

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rwg

rwg

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Finally got out from behind the keyboard into the garden last night (16th) - the sky was clear and the seeing was much steadier than the last few times I've been out. Still working on technique to some extent and testing changes to SharpCap, but actually managed to get some decent sequences of Jupiter with the GRS and a moon shadow moving across.

Images taken with a Microsoft Lifecam HD on a Nexstar SE8 with 2x Shorty Plus barlow + extension tube, so probably 2.5-3x or thereabouts.

Processing in AviStack 2. Unfortunately the moon images and the shadow show noticeable colour fringes, mostly due to the wavelet sharpening.

This version is at 50% size, which just goes to show I have to keep working on getting the focus bang on :D

Robin

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neil phillips

neil phillips

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Nice one,and nice colour balance for a lifecam,looks more like a spc.

It was rgb align that was off Buster was right, had a little play, ( hope thats ok ? ) think you got some detail on the moon there. Hope you like the result. I loved playing with this image.I mentally said wow at one point.

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rwg

rwg

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Ok, now it's my turn to say 'wow'!

Neil, what software did you use to re-align the RGB? How? I'm going to have to try that on my full size image. And I have another 3 movies to process that I haven't looked at yet :):D:D

cheers,

Robin

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rwg

rwg

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Aside from being interested in how best to process out the RGB misalign, I'm kind of curious as to how it got there in the first place?

I've just looked back at the original movie, and you can see it there for both the moons and the planet, so it's not really a processing artifact after all. The fact that it's an up/down misalign rather than any other directions makes me think it might be related to me using a diagonal when capturing, but that's just a mirror - surely it shouldn't introduce a chromatic aberration?

Robin

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neil phillips

neil phillips

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Its chromatic dispersion of the atmosphere producing the colour speration. the lower the planet the worse the effect. I used reg 5 for RGB ALIGN did it manually look at the moon, and just move the red up untill they align. I did a lot of other stuff too like frequency domain noise reduction on the seperate rgb channels. adaptive noise reduction on the red channel which i then saved. and used as a colour desaturated ( now smoother ) luminence, which i combined with the the worked on RGBs deconvolution. and mild unsharp mask. And colour noise reduction which also helped the moon problem

John maybe at some point i will write my techniques on a page. but they are very unorhadox, other sofware and techniques are probably better, but i use free sofware to do all this, and it seems to give me good results. like a lot of people i need to learn much much more. If theres a interest in what i do then ill write something up for others to try.

What did you set the lifecam on to get that colour balance. really very well done

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rwg

rwg

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Thanks Neil,

I would certainly be interested if you produced a walkthrough of this sort of procedure - I understand the meanings what you're saying you did, but I'm not sure I could do all the steps myself. I did try using registax just now to adjust the alignment of the red element and that works pretty well as a first stage of improvement - thanks for that!

Since the chromatic dispersion is atmospheric I presume it's pretty much a global problem in this sort of imaging. I'm now thinking of adding an option to SharpCap to allow you to correct for this in the preview to allow for easier focusing, and maybe even in the capture video too if it works out. It's easy enough to process the video stream and shift the red channel vertically a number of pixels.

thanks again for doing the re-process!

Robin

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bus_ter

bus_ter

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Aside from being interested in how best to process out the RGB misalign, I'm kind of curious as to how it got there in the first place?

You're right, it's not the processing, it's from the original image. Some of it comes from being low in the atmosphere, though a lot comes from the optics in the scope. Telescopes are generally very simple optical designs (unlike say a good multi-element camera lens where CA is not tolerated), and light at each end of the spectrum gets focussed at a slightly different point. You can buy expensive APO scopes with extra ED elements to 'correct' the focussing points of different wavelengths or as Neil so brilliantly showed you can process it out. Alternatively if you use a mono camera with colour filters and combine the images you've actually bypassed the problem!

A good way to improve CA is to use an IR/UV block filter (if you're not already). This is because the sensors are sensitive to light beyond each end of the visible spectrum, and once these show up on the computer image the CA is even worse.

You can easily test to see whether you need one of these filters (And indeed if the filter is working) by pointing a TV remote at the webcam and start pushing buttons. The webcam sees the 'invisible' light. Same thing works for cheap digital cameras (SLR's typically block out non visible light- and hence the need to modify them when you actually want to image IR..)

I think Neil should definitely produce an article showing his image work flow, as without a doubt he has one of the best and we could all improve our images with better post processing as shown above!

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rwg

rwg

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Well, encouraged by Neil's reprocess, I have had another go at processing the full resolution stack from this movie. All I have done is re-align the RGB components and sharpen with wavelet processing in registax, so fairly simple processing, but the result is quite nice.

Robin

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ps. how do you post a bigger image than the preview size? (ie so that it displays bigger without the need to click on it?)

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rwg

rwg

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Yes, this was a Nexstar SE8 and (approx) 2.5x barlow. The lifecam has more pixels on the sensor (1280x800) and the pixels are smaller than the toucam ones, so the image is bigger.

I have an SPC900 too, but use the lifecam for preference. I find it easier to work with (even though it has no manual gain), I prefer the large capture area and I find it nicely sensitive for faint stuff like bahtinov focusing spikes.

Robin

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