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Veil Nebula Witches Broom

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#1 snommisbor

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Posted 09 October 2013 - 08:02 PM

First real photo I have taken with my TEC 140 since I got it in Feb. Shot with a Nikon D700 at ISO 1250 and 36x5 min subs 28x5 darks and processed using the video by Scott Rosen. That was a very informative video. Thought it would be cool to crop it in a pano view.

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#2 mmalik

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Posted 11 October 2013 - 01:46 AM

Good attempt; you have over-done it a bit while practicing I guess. Try getting something similar (doesn't have to match) to this... in color and look. Regards

#3 srosenfraz

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Posted 11 October 2013 - 10:33 AM

I like the pano view - haven't seen it presented this way much and it really works well for this target. Thank you for the kind words about my video. A couple of suggestions that might help improve the image.

1) One of the big mistakes I made with the video is that Neil's M45 data took extremely well to a Screen Mask Invert at 100% opacity. Its unusual that an image can handle that well. For this reason, I almost always apply my SMI layers at 25% to 50% (typically). If you don't back off the opacity of the SMI, it will give the image a look similar to an overly noise reduced image. I'm seeing what looks like some of this effect in your image - particularly around the stars towards the left side and through some of the Veil to the left of 52 Cygni. I've found that your much better off doing two passes of SMI at 35% opacity than you are doing one at, say 70%. So, that's one thing I would recommend - less aggressive SMI layers. Again, its my mistake for not emphasizing this in the video.

2) You ended up with some good star color, but your nebula looks undersaturated to me (colors not very vivid). The way to improve this is to saturate the RGB image more before you apply the luminosity layers. Then, only apply the luminosity at whatever percentage opacity the saturation can handle. If the colors start washing out initially at 50% opacity, then stop there. Flatten the image, reblur it, saturate it some more and then apply the luminosity at a higher percentage opacity. Again, you're better off applying the luminosity a little at a time rather than all at once. Reblurring the RGB and reapplying the luminosity does not have negative effects, so you'll find better results by incrementally increasing the luminosity.

I can see you have some excellent data (not surprising with a TEC 140 and 3 hours of capture). Stars look great and you did an excellent job with keeping them small to enhance the nebula. A few tweaks and you'll have that much better an image.

#4 snommisbor

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Posted 14 October 2013 - 10:48 AM

Thanks for the tip, following along your video it is a 3 hour process trying to learn and starting and stopping and having to rewind what I might have missed, so I am sure doing it a few more times will yield better results. I was not happy with the color but will try it again. Hopefully it will go faster as I start to learn the steps just from repetition.

#5 Tom and Beth

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Posted 14 October 2013 - 12:48 PM

Now THERE'S a Witches' Broom!

#6 SKYGZR

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Posted 14 October 2013 - 05:47 PM

1) One of the big mistakes I made with the video is that Neil's M45 data took extremely well to a Screen Mask Invert at 100% opacity. Its unusual that an image can handle that well. For this reason, I almost always apply my SMI layers at 25% to 50% (typically). If you don't back off the opacity of the SMI, it will give the image a look similar to an overly noise reduced image. I'm seeing what looks like some of this effect in your image - particularly around the stars towards the left side and through some of the Veil to the left of 52 Cygni. I've found that your much better off doing two passes of SMI at 35% opacity than you are doing one at, say 70%. So, that's one thing I would recommend - less aggressive SMI layers. Again, its my mistake for not emphasizing this in the video.


At what point in the tutorial would this be done? When actually doing the Invert(s),when "grouping", prior to saving and flattening?...so adjust the opacity of the group(s) if doing mare than one SMI?

#7 srosenfraz

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Posted 14 October 2013 - 09:28 PM

You'll want to lower the opacity on the SMI group. This lowers the opacity equally on the SMI layer as well as the levels adjustment layer to bring it back down to original black point. In this way, you can adjust the group opacity and any amount of opacity will be valid - it'll only affect how much the overall SMI contributes to the image. Also, you'll want to lower the opacity of the group whether you're doing only one SMI, or multiple SMIs.

Hope that makes sense.

#8 SKYGZR

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Posted 14 October 2013 - 10:27 PM

Working on playing around with it now. Noticed that the opacity of each the SMI and Levels can be adjusted as well when within the group. Any benefits to playing with those as well as the entire group?

I can see subtle differences in the adjustments when doing this.

#9 srosenfraz

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Posted 14 October 2013 - 11:07 PM

The concept behind the levels adjustment layer is that the Screen mode of the SMI layer will brighten the entire image significantly as well as raise the black point. By adding a levels adjustment to bring back down the black point, you're left with an image that is brightened by the SMI layer, but primarily in the faint parts of the image (often the previously invisible faint parts). So, the levels adjustment should generally be "matched" to the SMI layer to restore an original black point. For this reason, I would favor only playing with the opacity on the group level (which keeps the levels adjustment and the SMI in sync).

That having been said, I suspect there's all sorts of different combinations that could have interesting effects. So, I certainly wouldn't exclude the possibility that there's other ways to make the SMI work better. No harm in trying!






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