NGC6888

[alan4908]

Paul and Wim

Thanks for the info - I shall have a look at the TGVDenoise  and SCNR within PI, I'll also examine the link within the PI forum. I presume that SCNR PI function is equivalent to the PS Plug-in HVLG. In PS, I always perform my noise and sharpening via object layer masks which I like since this allows you to apply varying amounts of noise or sharpening depending on the brightness of the object. 

Alan

[gnomus]

On 17/05/2016 at 12:54, alan4908 said:

Hi Gav

Welll, it's good to know that you don't have similar issues with your SW ED80. Maybe I'll try varying the distance, .....

Because the issue is relatively minor, it's very difficult to tell much about the elongation.  Looking at your image though, I get the 'impression' of the elongation all being in one direction.  This might indicate tilt rather than incorrect spacing.  I see that you have fitted a Moonlite to your ED80.  Is it possible that this is slightly off-axis?  I understand that it is possible to check this with a piece of paper over the objective and a laser in the focuser - the 'dot' should be in the centre of the circle.  It may be worth looking at this since the Moonlite's collimation can be adjusted fairly easily, I believe.

I also have an ED80 and I get round stars all over - I think it's a pretty forgiving scope.  

[alan4908]

58 minutes ago, gnomus said:

Because the issue is relatively minor, it's very difficult to tell much about the elongation.  Looking at your image though, I get the 'impression' of the elongation all being in one direction.  This might indicate tilt rather than incorrect spacing.  I see that you have fitted a Moonlite to your ED80.  Is it possible that this is slightly off-axis?  I understand that it is possible to check this with a piece of paper over the objective and a laser in the focuser - the 'dot' should be in the centre of the circle.  It may be worth looking at this since the Moonlite's collimation can be adjusted fairly easily, I believe.

I also have an ED80 and I get round stars all over - I think it's a pretty forgiving scope.  

Gnomus

You may be correct. I haven't checked the collimation of my Moonlite focuser since I installed it, mainly because I know nothing about how to collimate a refractor . However, what I have noticed is the non-ideal manner in which my SW FR/FF is currently attached to my Moonlite. Because the Moonlite focuser doesn't have the SW thread for the FR/FR, I  attach the FF/FR via a push fit connector...... this is obviously a weak point in the connection and I suspect that this is contributing to the tilt. Ideally I'd like to attach my SW FR/FF into the drawtube in the same way as I did before my focuser "upgrade" but I cannot see how to do this. 

Alan

[gnomus]

6 minutes ago, alan4908 said:

Gnomus

You may be correct. I haven't checked the collimation of my Moonlite focuser since I installed it, mainly because I know nothing about how to collimate a refractor . However, what I have noticed is the non-ideal manner in which my SW FR/FF is currently attached to my Moonlite. Because the Moonlite focuser doesn't have the SW thread for the FR/FR, I  attach the FF/FR via a push fit connector...... this is obviously a weak point in the connection and I suspect that this is contributing to the tilt. Ideally I'd like to attach my SW FR/FF into the drawtube in the same way as I did before my focuser "upgrade" but I cannot see how to do this. 

Alan

No I couldn't see how to do anything other than push-fit either when I fitted a Moonlite to my ED80.

I am not suggesting that you try collimating your ED80.  I am suggesting that you ensure that the focuser is lined up correctly in the tube of the ED80.  Mine just worked and I got round stars so I didn't need to do this.  But it is my understanding that you can adjust the Moonlite focuser itself.  I don't know how to do this, but I'm sure Moonlite (or FLO if you bought from them) could talk you through it.  Either way the laser and bit of paper should tell you if you do have that issue.

[alan4908]

1 hour ago, gnomus said:

No I couldn't see how to do anything other than push-fit either when I fitted a Moonlite to my ED80.

I am not suggesting that you try collimating your ED80.  I am suggesting that you ensure that the focuser is lined up correctly in the tube of the ED80.  Mine just worked and I got round stars so I didn't need to do this.  But it is my understanding that you can adjust the Moonlite focuser itself.  I don't know how to do this, but I'm sure Moonlite (or FLO if you bought from them) could talk you through it.  Either way the laser and bit of paper should tell you if you do have that issue.

OK - that sounds like a plan. I shall investigate further. 

Alan

[Rodd]

Wow--nice image.  I am attempting something like this with this target.  It takes so darn long to get 20 hours worth of data with the weather being what it is.  Its a testament to you diligence.  

[ollypenrice]

I particularly like your colour separation between the Crescent and the background.

This is good stuff.

Olly

[alan4908]

11 hours ago, Rodd said:

Wow--nice image.  I am attempting something like this with this target.  It takes so darn long to get 20 hours worth of data with the weather being what it is.  Its a testament to you diligence.  

Thanks for the complement Rodd, yes, trying to sufficient data is a challenge, I've found this can be overcome to a large degree by moving to automated imaging, given the poor UK weather, this has significantly improved my imaging efficiency.

10 hours ago, ollypenrice said:

 

I particularly like your colour separation between the Crescent and the background.

This is good stuff.

Olly

 

Thanks Olly - yes, I think it helped highlight the background/object contrast a little more 

Alan  

[alan4908]

 

On 5/19/2016 at 11:42, gnomus said:

I am not suggesting that you try collimating your ED80.  I am suggesting that you ensure that the focuser is lined up correctly in the tube of the ED80.  Mine just worked and I got round stars so I didn't need to do this.  But it is my understanding that you can adjust the Moonlite focuser itself.  I don't know how to do this, but I'm sure Moonlite (or FLO if you bought from them) could talk you through it.  Either way the laser and bit of paper should tell you if you do have that issue.

Well, after purchasing a laser collimator and then learning how to check if a laser collimator is collimated.......it would seem that my Moonlite focuser was slightly off center which I've now corrected.  So, thanks again for the suggestion !  I'll also check my PA and spacing when a clear night appears. In the meantime, I thought I'd also have a go at attempting to process out the starfield defects. So, having accumulated a little more knowledge about the various ways to make stars round, the result is below. I'm still not totally happy about the starfield but I think it is an improvement.

Alan

 

 

 

[swag72]

I like what you have done with the crescent, you've really bought the OIII shell out nicely and there is a super separation between the crescent itself and the background. For me, what hit me straight away was that I feel the background is overly smoothed, I'm guessing with some sort of noise reduction. In the darker areas there's nothing by way of texture and it just looks very uniform and glossed...... To me, any processing is too much if it can be seen  

Just my opinion though!!

[wimvb]

1 hour ago, alan4908 said:

 

Well, after purchasing a laser collimator and then learning how to check if a laser collimator is collimated.......it would seem that my Moonlite focuser was slightly off center which I've now corrected.  So, thanks again for the suggestion !  I'll also check my PA and spacing when a clear night appears. In the meantime, I thought I'd also have a go at attempting to process out the starfield defects. So, having accumulated a little more knowledge about the various ways to make stars round, the result is below. I'm still not totally happy about the starfield but I think it is an improvement.

Alan

As for laser collimating; have you seen/tried this method?

https://www.cameraconcepts.com/barlowed laser collimation.pdf

 

Cheers,

[alan4908]

2 hours ago, swag72 said:

I like what you have done with the crescent, you've really bought the OIII shell out nicely and there is a super separation between the crescent itself and the background. For me, what hit me straight away was that I feel the background is overly smoothed, I'm guessing with some sort of noise reduction. In the darker areas there's nothing by way of texture and it just looks very uniform and glossed...... To me, any processing is too much if it can be seen  

Just my opinion though!!

Hi Sara

Thanks for the comments.

Yes, there is definitely noise reduction in there, basically because I found that the Ha data was quite noisy  - so it is quite possible/probable that I've overdone this. To be quite frank I haven't paid much attention to this aspect of the image since I was mainly concentrating on attempting to fix the star field. I'll definitely take another look at this.

Alan   

[alan4908]

3 hours ago, wimvb said:

As for laser collimating; have you seen/tried this method?

https://www.cameraconcepts.com/barlowed laser collimation.pdf

Hi Wim

No, I haven't seen this article before, it's quite interesting. Unless, I've misunderstood the article, it appears to relate to reflecting scopes. Currently, I only have a refractor and was using the laser collimator to simply check the orthogonality of my focuser with respect to the objective. Thanks anyway.

Alan