Where's the colour?

[groberts]

I have recently been slowly getting to grips with the set-up and basic use of my new equipment (AZ-EQ6 & WO GT81 etc), with still some way to go.  I nonetheless have just succeeded for the first time in getting a good star and, in particular polar alignment.  Of course this is essential for locating and tracking images cracked, so with clear skies earlier this week I had to have a go at a longer exposure.  

Hitherto, my tracking has been limited to no more than 40 seconds and even this wasn't always great but with much better alignment (not perfect but getting there) I decided to try 90 seconds. Inspired by other posts I have seen on SGL recently and limitations to my sight-lines, I tried NGC7000 The North American Nebula on Wednesday night.  Also for the first time, using a Canon 700D and field flattener, I took a full set of darks, bias and flats for stacking with x20 subs at ISO1600 for 90 seconds.

I am thrilled with the result but am perplexed by the colour; I live near Gatwick airport so the plane track is a nuisance which I shall remove on restacking later.  Using Photoshop a clear and, for me, very exciting image of NGC7000 emerged but the dominant colour is a bluish green.  From other pictures I have seen the dominant colour is pink / red, so what's happening?

I presume that as my camera is unmodified it may be the influence of the IR filter but surely it would not remove all red?  On adjusting the Colour Balance the picture does turn red but is this just a Photoshop effect rather than the real colour?

NGC7000 DSS Stacked 240914curves-levels adjusted (Small).tif

NGC7000 DSS Stacked 240914adjustedcolourized (Small).tif

     

  

[groberts]

Having trouble posting pictures, rather than as attachments - help please?

   

[Grant]

There isn't a way to automatically display tiff files - please save as jpgs and then post and they will appear

[lensman57]

I have recently been slowly getting to grips with the set-up and basic use of my new equipment (AZ-EQ6 & WO GT81 etc), with still some way to go.  I nonetheless have just succeeded for the first time in getting a good star and, in particular polar alignment.  Of course this is essential for locating and tracking images cracked, so with clear skies earlier this week I had to have a go at a longer exposure.  

Hitherto, my tracking has been limited to no more than 40 seconds and even this wasn't always great but with much better alignment (not perfect but getting there) I decided to try 90 seconds. Inspired by other posts I have seen on SGL recently and limitations to my sight-lines, I tried NGC7000 The North American Nebula on Wednesday night.  Also for the first time, using a Canon 700D and field flattener, I took a full set of darks, bias and flats for stacking with x20 subs at ISO1600 for 90 seconds.

I am thrilled with the result but am perplexed by the colour; I live near Gatwick airport so the plane track is a nuisance which I shall remove on restacking later.  Using Photoshop a clear and, for me, very exciting image of NGC7000 emerged but the dominant colour is a bluish green.  From other pictures I have seen the dominant colour is pink / red, so what's happening?

I presume that as my camera is unmodified it may be the influence of the IR filter but surely it would not remove all red?  On adjusting the Colour Balance the picture does turn red but is this just a Photoshop effect rather than the real colour?

NGC7000 DSS Stacked 240914curves-levels adjusted (Small).tif

NGC7000 DSS Stacked 240914adjustedcolourized (Small).tif

     

  

That is the typical signature of an unmodded DSLR. A modded DSLR will pass through almost the entire Ha waveband an unmodded will not. As NGC 7000 is mostly a strong Ha region what you have is normal.

A.G

[D4N]

NGC7000 is an emission nebula, this means that most of the light coming out of it will be Ha (red) which is being filtered out by your cameras IR filter.

What you are picking up is OIII which is indeed a bluish green and not being filtered out by your camera.

It would be wise to aim for targets that aren't primarily Ha when shooting with an unmodified DSLR.

Sent from my iPad using Tapatalk

[groberts]

OK I thought that might be the case, looks like a modded camera one of these days! Nonetheless I am still very pleased with the image. Bye-the-way, what is that large star in the upper right side of the picture, just to the right of the plane's light trace.

Any suggestions that might be suitable candidates for my set-up in the eastern or southern sky - can't see north as my house is in the way!