IC1871 Soul Nebula - 1st attempt - tip

[vineyard]

Hello,

Hope everyone safe & well. After @vlaiv's tips on darks & offsets rescued my lights from last week 🙏🏾, here's my first wip on a part of the Soul Nebula. Only 3h8m of integration so I want to try and get a lot more data.  This was done w a CLS-CCD filter - I want to add a UHC to that to make a synthetic tri-band to see if I get some slightly different type of data as well.

Have been a bit more patient w the processing on this (taking more time w star-masks & testing tweaks etc), and remembering that less is more all the time.  So far am cautiously happy with where it seems to be going - but since I've never imaged this before, that's not an opinion based on much experience 😂

Not sure whether the star-reduced one is a better image than the fully loaded one.

Anyway, let's see where this goes!

Cheers & stay safe all - that R is rising.

Vin

[Pryce]

Noticed something weird with the blue in some of the stars.  No clue whats going on here!  

 

Star masks gone wrong?

[vineyard]

2 hours ago, Pryce said:

Noticed something weird with the blue in some of the stars.  No clue whats going on here!  

 

Star masks gone wrong?

 

Good Q.  I'm afraid I'm not experienced enough to know.  Will keep an eye on that as I collect more data.  There is still some curvature in all 4 corners, even though I'm using a reducer-flattener, so I also want to play with the spacing (its 55mm currently, but I want to try reducing that to 54mm somehow as the native focal length of the scope is 880mm given the steps in distance that the flattener seems to suggest) - maybe its something to do with that?

Cheers!

[Pryce]

1 hour ago, vineyard said:

maybe its something to do with that?

For what I understand about flatteners it wouldnt cause a colordistortion like that.  It would just elongate the stars.

My bet is that something went wrong in processing!

[vineyard]

On 18/09/2020 at 19:15, Pryce said:

For what I understand about flatteners it wouldnt cause a colordistortion like that.  It would just elongate the stars.

My bet is that something went wrong in processing!

I think it was the offset was too high - the blue curve was being bumped up far too much (and then probably amateurish post-processing).

I tried the same target w offset 16 and the blue distortion isn't there (example below).

Cheers

[Pryce]

That looka waaaay better!  Good job mate!

[peter shah]

great image ...the later rendition is so much better

[vineyard]

Thanks both - yes I feel a bit happier about this one - want to get a lot more data on it (next time when the skies clear).

Btw I also discovered why (hopefully) I was getting a bit of curvature in all 4 corners.  I thought I'd set the back focus distance to 54.5mm (close enough to 55mm for a first stab) and then realised that it was actually 59.5mm!  Clearly I'm an idiot whose ability to do simple arithmetic is rapidly decaying to zero.

Have set it to 55mm now & hopefully that will fix the curvature - which means, fingers crossed, I can start taking mosaic panels (although I suspect a camera rotator may be helpful for that given that it might be quite a few days to complete captures?)

Cheers & stay safe all