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First real attempt Orion Nebula


Scott Tilley

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Well, it came as a bit of a surprise but finally managed to get out for an hour last night. Hurridly set up the scope and had a really enjoyable time until it got too windy to continue. Anyway, this is what the image is made up of:-

10 x 55sec

10 x 45 sec

5 x dark

5 x flat

All taken with my unmodded canon 50d attached direct to my SW 200p and with no filters. Stacked in DSS and curves adjusted in photoshop. Must admit I really struggle with the post-processing so any advice would be gratefully recieved.:headbang:

Scott

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Very good first effort - its looking good!

The trick with the colour-cast is to open levels first, and set the black-point to the surrounding area - this will bring the RGB channels into line with each other. Click the black dropper in levels, and then click a black area of the picture - you should see the histogram move so where there were 2 or 3 peaks (see levelsbefore.jpg below), only 1 exists now (see levelsafter.jpg below)

Attached is the resulting after a little play with curves as well - hope you don't mind!

You've got quite a bit of Vignetting in there as well - not surprising really, but you will need to take flats to get rid of this, or use false-flats, or as I did, used Gradient Exterminator on the second image :headbang:

Cheers,

Richie

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Thats very nice, there is a lot of detail in there. If you want to PM me the original stacked version (not the JPG) I will have a play with it and try to remove the slight orange cast.

Very nice image though!

Hi, would love to take you up on your offer, how do I attach the original image to the PM?

Thanks again.

Scott

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You have captured some good data there, well caught! The images is overly red but this can be adjusted fairly simply. The following may help with instructions for both PhotoShop and The Gimp:-

From PhotoShop, select Layer - New Adjustment Level - Levels and you will note the default histogram is that of ‘RGB’. Using The GIMP, select Layer - Duplicate Layer then Colours - Levels where you will find the default histogram shown is ‘Value’. Using the drop down list box, choose the RED channel. You will immediately note a change to the histogram display. On both programs, ensure that the ‘preview’ option is selected so that you can see the changes that you are making to the appearance of the image in real-time. Slide the left hand ‘slider’ to the right until it is lined up with the start of the steep ‘slope’ of the histogram - it is important not to go past this point or you will be clipping your data. You will note that the image has changed its hue to a greenish tinge. Now, repeat the process for the green channel, noting that the hue has now got a blue tinge to it. Finally, repeat the process for the blue channel and you will be rewarded with a much better background sky colour and a far better colour balanced image.

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