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Problems with Jupiter


robindurant
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Hi

I have just set up Registax on my Computer and have had two frustrating nights trying to image Jupiter. I think that I am doing something wrong as I cannot gey any detail whatsoever on the resulting videos, just bright clear of detail discs.. I have tried many settings on Registax and I havn't a clue as to what setting to use for a Planet such as Jupiter. It is possible that I am not focussing correctly. I focus until I can see Jupiters Moons on my Computer screen, maybe this is wrong. Help !!

Robin

Celestron 8iSD. Neximage imager

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Check this out

http://stargazerslounge.co.uk/index.php?topic=3523.0

It should be a link to the learning zone bit about planetary imaging.

Also if you can get hold of a copy of last month's Practical Astronomer you will get loads of tips.

My guess is that you had the capture too bright and that's why you are struggling.

Try using virtualdub to chop the AVI into smaller segments of only a few frames then Registaxing. This might remove the overbrightening effect.

Captain Chaos

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Thanks for your reply. I am ok with Registax it is the settings on the Neximage I am having problems with. In the instructions they dont give any suggestions as to the settings except for the moon. I have tried moving the brightness adjuster, dark and bright with no result, still a blank white disk before and after stacking. One thing I have noticed is that the images take ages to optimise, could they be too over exposed, but then I don't see any adjustment on the Neximage camera pane to adjust. It only gives Frames per sec 5 - 30 Time ( if I try over 30 secs the Registax wont take it. Over 1 GB) There is an auto button, (no good) When I run the video the image looks just as was when I took over exposed pics woth my Canon 350D camera -- Questions, should I be focusing by picking up Jupiters Moons and should I be able to see details of the planet ( which incidently is approx. 1 1/2 " dia on the screen ) on my Computer screen after focusing, which I can't -- So many questions but I am a novice to astro imaging and appreciate the past help I have recieved,

Robin

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If you are getting a white disc rather than banding you need to adjust your exposure down. something like 1/25th seconds maybe? The gain should be as low as it will go without the image vanishing. You SHOULDN'T be able to see the moons if you want to get surface detail. The 2 are NOT compatible unfortuantly. To see the moons you have to over expose the surface. Images with both moons and surface detail are composites of 2 images with different exposures.

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If the overall brightness/contrast of the scene is too low, you'll get the dreaded onion-ring effect.

That's an excellent tip Pete. I've had a number of onion rings and other captures which make Jupiter look like a Big Mac.

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If you get yourself a capture program like K3CCDTools (http://www.pk3.org/Astro/index.htm?k3ccdtools.htm) it provides a level meter on the side of the capture window. Using this, you can take short exposures, note the setting of the meter each time and see which level gives the best results. I used to capture low and got the onion ring, now I capture high and get much better results.

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If anyone does get the Onion ring effect i suggest you get it into photoshop use the Magic wand tool select the Onioned effected area and use a Guass blur filter most of the time this will clean the Image up :). Better to use Pete's Tip though as you will loose some information useing the Guass Bur..

James

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Hi Gordon, I only found out because I was fed up of the poor images I was getting. I decided to sit down and scientifically see what different settings would deliver. I used to keep things dark but now I've seen the light :)

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Thanks all

I have now solved the problem thanks to your advice, which turned out to be over exposure. I Caught Jupiter last night behind much crappy atmosphere and got reasonable results considering. BUT after taking the images OK I find a problem with Registax in the Optimizing stage, it takes ages. I processed images at 30 FPS 30 seconds 1/50 shutter speed it aligns fast enough but takes 2-3 hours to optimize. I have tried various ways of processing but all take ages. Is this right? it doesn't happen with Keiths Stacker. I have a new Laptop 1.7 GHz and other image files seem to be fast enough, Maybe my software is faulty it does seem to freeze many times when I try to load a video. Tanks again for past help.

Robin

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Robin

How big is the file? At 30 fps, the file is going to grow very quickly. Registax has a 2GB limit (I think), but you can get a lot of frames in that size.

1 min = 1,800 frames

2 min = 3,600 frames

4 min = 7,200 frames

10 min = 30,000 frames

CC made a good suggestion of using VirtualDub to either split the file down, or delete the worst of the images before passing to Registax.

I would also try reducing the FPS to 10 and doing a 60 second capture and try that.

Let us know how you get on.

Pete - great tip on the low/hi light thing. I feel a new spreadsheet coming on! :)

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30fps with a conventional webcam? If so, that's far too high. 5fps and 10fps will allow you to capture without frame compression. Anything above this and the frames will be compressed to maintain the speed. Compressed frames will introduce artifacts and you'll never get a decent result.

Here's a scary test - image something in daylight - e.g. a distant tree, telegraph pole or brick wall with lots of fine detail. Treat it like a planet and see just how good an image you can get of it. It's not as easy a it sounds and it really shows the effect of upping the frame rate.

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Hi

Thanks for all the replies, it seems that my main fault was using too many frames per sec. Last night I set the camera at 5 FPS at 30. 60 & 90 sec duration and got good results considering the low altitude of jupiter and the bad sky quality. Thanks again, this is really an excellent Forum especially for those new to Astronomy.

Robin

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Hi all

Looking at this thread, I thought I'd try and find an example of a "correctly" exposed AVI. I found this one from June 6th, which I had not got round to processing before. Top left is a single frame from the AVI with nothing done to it. Top right is a 385 images stacked and stretched. The bottom image is resampled 85%.

As Pete pointed out , the cardinal sin in planetary imaging is underexposure, especially with Jupiter.

Regards

Nick

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Nick

Thanks very much for this, it gives a much clearer idea of what we should be aiming for!

I know that my attempts at Jupiter look worse than your single frame, but under-expsoure appears to be the key, here.

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