My First Nebula - M27

[Thalestris24]

You might think about trying a Ha filter to add as an extra luminance layer.

There are People that do this with their OSC cameras to improve the overall image.

Tho, they usually use a mono camera alongside their OSC, there are plenty of people doing it with just an OSC camera. Especially since your QHY8L has 50% QE in red.

It won´t increase the resolution, as you only capture with 25% of the pixels on the OSC sensor.

But as the Ha filter will guarantee block all Light Polution, you can take very long exposures with it (only Limited by your PA and guiding) and so definitely collect more data.

Hi Guillermo

Thanks. I'd thought of doing that tho the Halpha would only bring out the red. I guess I'd need an  OIII filter too... Hmm... getting expensive and maybe impractical for me. I can only take exposures of  up to 36mins max (cos of the window), which is limiting. I dunno, will have to think about it! Maybe I should get some narrowband filters anyway but I need some that I'll be able to also use with the mono 1100d. Not sure how to arrange that yet...  

In the meantime I might be able to have another go tonight so will take some longer exposures and try and merge them with the current ones somehow. I feel intuitively it would be possible to do that though I have no idea how! Perhaps by putting the longer exposures in a separate layer, with stars masked out, then merged down? I'll have to have a play

Cheers

Louise

[DoctorD]

Hi Louise

Your second version is good - 10x360s should be enough to get a reasonable image of M27 as it's quite bright.

Here's my M27 based on 20x 10 second exposures with my video camera, C8 at F2.8:

Although I'm a beginner astrophotographer  also, Ive found that the post processing (after stacking) can make a huge difference and there are techniques for stretching and masking that can control the size of your stars.

You could have a look at the tutorials here although they are very Photoshop centric:

http://www.budgetastro.net/video-tutorials.html

In particular I found the use of curves (Basic processing Part 5 - Curves) to stretch the image applied in several stages very useful, in particular learning how to "pin" the black level using control points on the curve.

Keep up the good work - imaging from light polluted locations may be difficult, but not impossible, we just have to accept the limitations of our environment.

Clear skies

Paul

[Thalestris24]

Hi Paul

Yes, I've post-processed my images with StarTools - I only have Photoshop CS2. Startools is purely for processing astro images  

Louise

[Thalestris24]

Hi Paul

ps I watched Gav's videos - very useful, thanks! I'll try and do some additional processing in CS2 with the curves + layers utilities, though it's only 8 bit. Maybe I can improve things!

Louise

[Thalestris24]

Hi all

So, after watching Doug's (not Gav's!! - was thinking of someone else before...), I had a play with curves adjustment layers etc. and have maybe improved the nebula colours/contrast a little bit? I only have CS2 so not sure whether that makes a big difference, or not!

Anyway, here is revised version and a crop of the nebula.

With a bit of luck might be able to get some more subs tonight - if the Met Office is to be believed...

Cheers

Louise

[wxsatuser]

Thats coming along quite nicely Louise.

Some more data and I think you will have a very nice M27.

[Pete Presland]

this an interesting thread and shows what can be done from a less than ideal location. that is a nice M27 and considring you are limited to such a short time for the target all credit to you, well done!!!

[Thalestris24]

Thanks Mike and Pete I got some more subs last night but atmosphere quality was poor so guiding not so good Will be hoping some are useable - will have a look shortly I took some 600s subs as well, though they came out bright yellow!

Cheers

Louise

[Pete Presland]

Thanks Mike and Pete I got some more subs last night but atmosphere quality was poor so guiding not so good Will be hoping some are useable - will have a look shortly I took some 600s subs as well, though they came out bright yellow!

Cheers

Louise

i but i watched a video about a guy that lived in a large light polluted city in Los Angeles, California. he had a technique called  "Expose to the Right" where he exposed the image so much that the histgram was right over to the right hand side, then processed it back to nearer where it should be. considering what they started like his images look pretty decent

http://www.lonelyspeck.com/the-milky-way-in-los-angeles-light-pollution/

this was widefield so maybe not relevent to you but i thought i would share it anyway.

[Thalestris24]

i but i watched a video about a guy that lived in a large light polluted city in Los Angeles, California. he had a technique called  "Expose to the Right" where he exposed the image so much that the histgram was right over to the right hand side, then processed it back to nearer where it should be. considering what they started like his images look pretty decent

http://www.lonelyspeck.com/the-milky-way-in-los-angeles-light-pollution/

this was widefield so maybe not relevent to you but i thought i would share it anyway.

Thanks Pete - I've seen that before but, as you say, not really relevant with a scope and a ccd. It's true, though, that my subs tend to be 'overexposed' because of the lp and I compensate via processing - which is a similar idea to the video.

Louise

Louise