M101

[Astrosurf]

This is my first attempt at M101. I still have a long way to go to get my processing good, but I'm quite happy with it!

It's a DSS stack of 10 subs of 7 mins each (wish I could have got more) plus darks.

Alexxx

[Gina]

Very nice

[swag72]

I looked at this and thought it was clipped. I downloaded the Jpeg and opened it in CS5. As you can see by the screen grab, the levels adjustment box shows that you have indeed clipped the black, as there's information dropping off the left hand side - I've circled the area that I mean. You want to avoid this and keep an eye on the levels as this means that any data that is dark (often nebulosity, or spiral arms) is lost forever and replaced by black pixels.

Avoid black clipping. I think that the colour balance may be a little off as well, but with the histograms clipped it's difficult to tell.

Hope that helps.

[Pig]

Excellent image very nice indeed

[Astrosurf]

Thanks all.

And thanks Sara. My original TIFF isn't quite so cropped on the black, but still a bit cropped! I do try to avoid it but just wanted the sky darker. I tried to stretch it a bit more but couldn't without it going wrong. I maybe should try to isolate the core when stretching at later stages. Can you advise what I should do to improve the colour and stretching? I've balanced the colour channels though it does still look too blue. Your images on Flickr are amazing! I'm reeeealy envious! I wish I could afford an Atik.

[swag72]

Thank you for your kind word Alex, but I am far from an expert! Especially with processing, For me, the capture is the easy part!!

All I do is stretch, then look at the levels and move the black point to the right if there is space, never clipping the data. A few iterations of that and as you say, process for the core without touching the background.

For increasing the colour there is a trick to change the image to lab mode and adjust contrasts, but here in the obs I cant be sure of the steps and I'd not want to get it wrong. I'll get back to the thread tomorrow if no one has beaten me to it!

[swag72]

To boost colour without increasing noise in Photoshop.

1) Duplicate layer (I like to do this only so I can see the changes and decide whether I want to keep them)

2) Image --> mode --> Lab colour (Don't flatten when asked)

3) Channels tab --> Channel A --> Select so that it is highlighted in blue

4) Image --> adjustment --> brightness / contrast

5) Type 30 into contrast box

6) Now unselect channel A and select channel B

7) Image --> adjustment --> brightness / contrast

8) Type 30 into contrast box

9) You must get each channel ( there are 4 in total) visible by clicking on them so that they all have an 'eye' beside them.

You can now look at the difference between the 2 layers (before and after) in the layers tab. Your work in the channels tab is done - Convert back to RGB colour.

Hope that helps.

[Astrosurf]

That's really great Sara! Thanks so much for going to the trouble. I'll give that a go and let you know how I get on.

X

[cfpendock]

I like your sharp stars.

chris

[Astrosurf]

Thanks Chris. My Bahtinov mask is an essential part of my kit!

[Astrosurf]

Sara, I had a go at your colour enhancement technique. It's really subtle and very good!

[Gina]

I'll try it myself next time I do processing - thanks Sara

[swag72]

Glad that it worked! You can save it as an action, one button press and it's done!!

[Astrosurf]

Glad that it worked! You can save it as an action, one button press and it's done!!

I do keep forgetting about Actions. Must remember!

[Gina]

Something else for me to try - thank you Such a lot still to learn

[peroni]

Sara, I had a go at your colour enhancement technique. It's really subtle and very good!

Can you post the reworked picture to show the improvements of the colour enhancement? It sounds like a technique to try.

[Astrosurf]

It was very subtle on the one already processed, but I wanted to have a go using the technique during a new process. Let me have a go at that and see if the result is strong enough to show you! I'll post it here as soon as it's done.

[swag72]

It is subtle, so you can always do it a couple of times!

[Astrosurf]

That's very true!

[swag72]

You can also do it in a seperate layer and adjust the opacity to suit of the top layer, you don't need to use it all!!

[Astrosurf]

When I do adjustments on a copy layer, and then flatten at the end, it shows all the adjustments I made. Please can you explain when you say I don't need to use it all? I've got soooooo much to learn!

[swag72]

Have your original open. Duplicate the layer so that you now have 2 images in the layers tab. Do the colour changes on the top layer only. Then you can move the opacity slider from 100% in order to get a percentage of the change. make sure that both layers have the eye beside them at this stage, so that they are both active.

[Astrosurf]

Oh, I get you!

Here are before and after screenshots of your method while I'm processing - not finished yet! You can clearly see the colour coming in.

[Scott]

Oh great.... more information I've got to cram into my already overflowing brain (the capacity wasn't a lot to start with). Thanks for that bit of info Sara, I'll give it a go.

[Astrosurf]

I know what you mean Scott! I'm saving documents on my Laptop to an astronomy instructions folder so I can see what I've used. I also write in a document what I've done on a particular processing so I don't forget! I'm pretty sure you can save actions on PS but I don't know how.

Here's the sort-of finished product.

Sara, it's a bit too red but I've lined up the colour channel peaks. I didn't clip the black this time. What would you recommend for further processing??