Wizard Nebula - can't see where I'm going wrong.

[CraigD1986]

Thanks for everyone's help with this. I've been persevering with this problem and I'm now wondering if the problem is caused by noise reduction (EZ Denoise in this case). Attached is a screenshot showing the data after the following processes:

Crop, DBE, Bills unlinked stretch, Starnet

I think the result looks a lot better and is worthy of continuing processing.

[AstroNebulee]

21 minutes ago, CraigD1986 said:

Thanks for everyone's help with this. I've been persevering with this problem and I'm now wondering if the problem is caused by noise reduction (EZ Denoise in this case). Attached is a screenshot showing the data after the following processes:

Crop, DBE, Bills unlinked stretch, Starnet

I think the result looks a lot better and is worthy of continuing processing.

That's definitely much better indeed. I know nothing of processing on PI. I think you've got it where you need to be now and your workflow is progressing well. It's all about little tweaks here and their to refine your workflow. It's all a big learning curve and one where we continually learn more and more. Well done. 

 

Lee

[CraigD1986]

On 22/03/2023 at 20:30, alexbb said:

Regarding your original question - have you tried to remove the stars after a stretch?

A 5 minutes play in PixInsight with the XTerminators + LHE and MLT can easily reveal some additional signal and details. Spending more time can improve the outcome, of course.

You've managed to get a spectacular amount of detail out of that! That's an amazing image for a 5 minute process. If you can remember, could you share your workflow on this? You've got so much out of it, especially in the reds at the top of the image.

I tried removing the stars both before (in linear mode) and after stretching but got similar results each time.

[CraigD1986]

On 17/03/2023 at 11:07, vlaiv said:

Don't waste time - this is not sensor or focuser tilt.

Sensor or focuser tilt shows distinct pattern:

- there will be spot or rather "band" in the image where stars will be tight

- usually corners suffer and besides stars being slightly out of shape in some corners - they are also slightly out of focus.

In your data - you have teardrop shaped stars all over the frame equally.

Effect it the same as atmospheric dispersion - which separates wavelengths of light in one direction. If you want to understand how this effect might be formed in objective lens of a telescope - check out atmospheric dispersion corrector - which has two prisms and changes their relative position to cancel the effect of atmosphere.

You have two lens in your objective (that on small section act as prisms) and if those two are similarly displaced (or one is displaced with respect to the other) - you will get the same effect. You have 3 modes of displacement.

Tilt of one of lenses with respect to the other.

Change of spacing between the two.

Axis displacement (one lens being shifted "up"/"down" so that two axis are still parallel but don't align any more).

Out of these three - first and third can produce above effect. Second one usually produces increased spherical aberration (just bloated stars but still round).

Why don't you do a simple star test - take image of slightly in / out focus star - to see what sort of pattern it presents - and then we can know more.

I've tried to find out a little about collimating a doublet refractor but there doesn't seem to be much info out there. I did once accidentally remove the front glass element when trying to remove the lens hood. I therefore just removed this again to re-fit it just incase it wasn't in straight or something. In doing so, I realised that both pieces of glass are in the same housing at the very front of the scope. I therefore don't think I could have misaligned one of them. Do you know where I can start looking to find some more info of checking the optics of this scope or collimating it if necessary?

[AstroNebulee]

1 hour ago, CraigD1986 said:

I've tried to find out a little about collimating a doublet refractor but there doesn't seem to be much info out there. I did once accidentally remove the front glass element when trying to remove the lens hood. I therefore just removed this again to re-fit it just incase it wasn't in straight or something. In doing so, I realised that both pieces of glass are in the same housing at the very front of the scope. I therefore don't think I could have misaligned one of them. Do you know where I can start looking to find some more info of checking the optics of this scope or collimating it if necessary?

I collimated my 72ed in this post if you read a bit of the way through it, using a laser collimator (collimated) and a paper mask. I never touched the object glass as this was fine.

https://stargazerslounge.com/topic/389932-eggy-stars-my-sensor-too-close/

Lee

 

[CraigD1986]

9 minutes ago, AstroNebulee said:

I collimated my 72ed in this post if you read a bit of the way through it, using a laser collimator (collimated) and a paper mask. I never touched the object glass as this was fine.

https://stargazerslounge.com/topic/389932-eggy-stars-my-sensor-too-close/

Lee

 

Thanks so much, I'll have a read and will get a laser collimator

[alexbb]

On 10/04/2023 at 15:01, CraigD1986 said:

You've managed to get a spectacular amount of detail out of that! That's an amazing image for a 5 minute process. If you can remember, could you share your workflow on this? You've got so much out of it, especially in the reds at the top of the image.

I tried removing the stars both before (in linear mode) and after stretching but got similar results each time.

For a quick look of what's going on in a dataset, an usual workflow could be like this:

DBE, crop, background and colour calibration, Blur XT, arcsin/HT stretch, Noise XT at 50-75% with inverse luminance mask, Star XT, additional HT stretch to different level on the RGB channels if needed, maybe a SCNR, then add the stars back with pixelmath and run another Noise XT if needed.

Star XT usually gives a cleaner output compared to Starnet 2. If you're using Starnet v1, try upgrading to Starnet 2, it provides better results.

[CraigD1986]

Thanks for clarifying. I've tried a few times and can't manage to extract nearly as much data as you have there. I'll keep trying though. I'm using Starnet 2.

[ollypenrice]

I think it's certainly true that there will be no going back from the star removal procedures now available. Processing is transformed. This is by far the biggest advance in any aspect of astrophotography that I've seen in the fifteen years I've been doing it. You can get so much more out of the nebulosity once you are not trying to control the stars at the same time.

The data are clearly very good.

Olly

Edited April 16, 2023 by ollypenrice
False click