bode's and cigar help with colour

[Callum1985]

Hi all, 

I have had a go at bodes and the cigar galaxy last night but i am really struggling to get any colour in the stars and feel that the galaxies themselves should have more detail, 

i was hoping that someone could let me know if this is a processing issue (maybe to heavy on the curves) and quite new to PS or if this is a camera setting (iso to high ??). 

subs are 180s iso 800 x 40 with a canon 100d (unmodified) with a CLS clip in filter,  through a skywatcher 200p, PHD2 for guiding 

dss for stacking and photoshop for editing . I have attached the TIFF and what i have managed to achieve with PS

 

thank you for any help 

 

bodes.TIF

[geeklee]

HI @Callum1985  I think the colour challenges are to do with the CLS filter.  While being a light pollution filter, looking at the transmission graph, it seems more ideal for nebula as it cuts a huge range of broadband light out.  If I remember these can give the image that green/blue ting you're seeing.  A lot of it can be corrected in processing, but it can take extra effort.

For the detail, I'm not sure - I think you've captured some really nice stuff there and M82 especially holds nice detail.  

I see artefacts in some stars - do you have a coma corrector in there, is collimation good and how was guiding on that big 200P?!  

Apologies, it's not via PS, but this has been colour balanced a little more.  Hopefully a PS expert will jump in and add to this!

Edited April 17, 2021 by geeklee

[Callum1985]

Hi @geeklee thank you for this, I have no coma corrector but the scope was collimated before the session, guiding was not to bad at all, i did some 5min subs as well and no visible trails where noticed, I settled for 3mins as thought this was the reason i wasn't getting any colour, but i will look at maybe trying again without the filter to see what benefits this holds. I'm bortle 5 skies so light pollution really hits hard on subs that are long. 

what's the difference between a field flattener and a coma corrector ? as you mentioned i get artifacts around the stars  is this the elongated stars around the edge of the image? and is that what a field flattener will reduce ? 

[geeklee]

3 hours ago, Callum1985 said:

what's the difference between a field flattener and a coma corrector ? as you mentioned i get artifacts around the stars  is this the elongated stars around the edge of the image? and is that what a field flattener will reduce ? 

I tend to think of a field flattener typically for a refractor and a coma corrector for a newtonian.  As far as I know all newtonians will suffer coma to some degree and for imaging a coma corrector helps those edge shapes that you mention.

If you can wipe the gradient/background and get colour calibration I think you'll be happier with the image - although you should be already as it's got some great qualities to it.

3 hours ago, Callum1985 said:

I settled for 3mins as thought this was the reason i wasn't getting any colour, but i will look at maybe trying again without the filter to see what benefits this holds. I'm bortle 5 skies so light pollution really hits hard on subs that are long. 

I'm in similar skies, perhaps 6 or worse in some directions so know what you mean.  Another thing to remember with the CLS is because it cutting out a huge chunk of broadband light, thus letting less light in, exposures may need to be longer.  Definitely worth trying without the filter but as I mentioned above you should be pleased with the image too - as it is and with its potential to get a little more out of it.

Edited April 17, 2021 by geeklee