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Jupiter 24-02-2016 Barlow Comparison


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Both images were taken with a logitech Quickcam Pro 4000 in a Skywatcher 200p. The Mount was an EQ5 with RA Motor drive. The first image was taken about 03.10am using a Astro Engineering AC333 apo x2 Barlow with an extension tube giving it a slight magnification boost:


From left to right; Io, Ganymede, Jupiter and a very faint Europa to the far right.

The second picture was taken about 03.52am with a £10 ebay 5X barlow from china labelled as "apo"


Just Ganymede in shot this time. Seeing conditions were pretty much the same for both shots and both were processed in a similar way using PIPP, AS2, Registax Wavelets and GIMP. Lots of CA in the second image although to be fair I wasn't expecting much for a tenner. I think I need to be on the lookout for a quality high powered barlow when I scrape some cash together.:icon_biggrin:


Edited by cuivenion
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It's certainly better than the 2x barlow that comes with some skywatcher scopes. There's two types that they come with and one of them is terrible. I bought one for a lot more than £10 and have since turned it into an extension tube.

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Nice images of Jupiter.

How did you use GIMP in the post-processing? I've installed it on my PC but am not having much success as I've no real idea how to use it - the YouTube tutorials don't seem to be applicable to astro image post-processing.

Any tips or pointers to onlline resources would be very welcome.

P.S. Stephen Green - we are about 10 miles away from each other. Do you ever get to the astro meetings at the Herstmonceux Science Centre? I'd be interested in swapping war stories about Celestron OTAs.

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Hi Doug with these images I adjusted the saturation in the red channel slightly (Colors>Hue-Saturation). I also adjusted the the Brightness-Contrast and the Curves both of with are found in the Color bar. I tend to use gimp for finishing touches, just small changes to enhance the detail. This is the pre Gimp image:


Before you export the file got to (Image > Mode > Convert to Color Profile) and make sure the Color Profile is set to sRGB, that way you can be sure your images will display properly on the internet. I exported the file as a PNG (File>Export As). When exporting choose all the options apart from Deinterlace (Adam7) and choose minimum compression.

Apparently PNG compression is not lossy but its not a large file anyway.

You have to export the file not save it. If you save it, it saves as a Gimp project and you can only access it through Gimp.

My last piece of advice is to do any stacking or processing on a well calibrated monitor, preferably not a laptop and be prepared for your photo to look different on different devices. It's very annoying.

I'm afraid I don't have any links to share, I just played around with different settings until I found what worked for me. You may find that procedures are different when working with different files. Good Luck.

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