Pleiades (M45) Star 71 and 100D

[StargeezerTim]

This is another experiment with low iso subs from last night. 47 X 5 min, iso 100, DSS and PS (with DBE for gradient). 

I'm not that impressed with it. I find this DSO difficult to process without really over stretching the stars and creating large halos. Anyone any tips on keeping the stars and halos under control when processing M45?

 

 

Edit... Here is a reprocess where I have retained more colour and it looks more natural i think.

 

 

[wimvb]

25 minutes ago, StargeezerTim said:

I'm not that impressed with it. I find this DSO difficult to process without really over stretching the stars and creating large halos. Anyone any tips on keeping the stars and halos under control when processing M45?

This is a target with bright stars and a lot of variation in the nebulosity; in other words, a huge dynamic range. Shooting with low iso makes sense. As far as processing is concerned, since you have PixInsight (you used dbe), have you tried masked stretch (under Intensity Transformations)? This tends to keep the stars smaller while lifting the dust. Use it with care, because too much of it will reveal artefacts in the background. Top off with curves stretch.

If you have light pollution, you may need to repair the star cores before MS.

[tooth_dr]

Thats nice TimI would be happy with that!

 I actually have a similar amount of subs in 5 mins at ISO 1600, taken over thep ast two nights.  If I get a chance to process and post it this weekend I'll tag you in it.

[StargeezerTim]

Just now, tooth_dr said:

Thats nice TimI would be happy with that!

 I actually have a similar amount of subs in 5 mins at ISO 1600, taken over thep ast two nights.  If I get a chance to process and post it this weekend I'll tag you in it.

Cheers, it will be interesting to see any obvious diffs. I'm actually happy that iso 100 seems to have captured a fair amount of the nebulosity. The autosave files are nothing to look at but they could be stretched more before noise reared its ugly head. I'll try the same on andromeda tonight if the clouds stay away.

[StargeezerTim]

8 minutes ago, wimvb said:

This is a target with bright stars and a lot of variation in the nebulosity; in other words, a huge dynamic range. Shooting with low iso makes sense. As far as processing is concerned, since you have PixInsight (you used dbe), have you tried masked stretch (under Intensity Transformations)? This tends to keep the stars smaller while lifting the dust. Use it with care, because too much of it will reveal artefacts in the background. Top off with curves stretch.

If you have light pollution, you may need to repair the star cores before MS.

I don't have the full pixinsight, but did something similar in PS by creating a star mask before three lots of curves and levels. I'll have another play with it. I do have lp here and there was a nasty gradient after stretching that needed working on.

[peter shah]

You have a very fine image. I always use  this method of curves with photoshop which helps keep stars under control, it also helps with retaining star colour.  Curve 1 is the first extreme curve i would normally apply after I set the black point in levels. this will cause the image to brighten up. The second curve is to bring the black point back to a good level. The next set of curves would be less extreme. The most important part of doing this is to make sure the last three quarters of the each curve line is flat all the way back to the white point. If you don't do that then your stars will bloat and loose colour.

[StargeezerTim]

1 hour ago, peter shah said:

You have a very fine image. I always use  this method of curves with photoshop which helps keep stars under control, it also helps with retaining star colour.  Curve 1 is the first extreme curve i would normally apply after I set the black point in levels. this will cause the image to brighten up. The second curve is to bring the black point back to a good level. The next set of curves would be less extreme. The most important part of doing this is to make sure the last three quarters of the each curve line is flat all the way back to the white point. If you don't do that then your stars will bloat and loose colour.

Thanks Peter,

I'll try that next time. I tend to use levels to shift the black point after curves instead of your second curve. I've also done a better job just now. The stars are still bloated but I have retained more colour and brought out more nebulosity. I'll attach it to the first post.

[wimvb]

3 hours ago, StargeezerTim said:

I don't have the full pixinsight, but did something similar in PS by creating a star mask before three lots of curves and levels. I'll have another play with it. I do have lp here and there was a nasty gradient after stretching that needed working on.

In ps, you could try this

http://adsabs.harvard.edu/full/2012JRASC.106...86M

Great rework, btw.