How difficult is M45?

[nightster]

I am not sure why by M45 is getting the better of me for the past 2 years.  When I think I got it figured out another roadblock pops up.  Right now I think I have the data but the processing is killing me. Am I overthinking this or can this truly be a difficult target to process?  

[sternenben]

Do you have any examples you can post of what is going wrong in your previous attempts?  

If you upload a stacked TIFF of your latest attempt I'll give it a quick try in PI.  

[nightster]

I wholeheartedly appreciate the offer to check out my data.  Here is a Dropbox link to the XISF subs, let me know if you need a different format. Fully calibrated in PI.  If anyone else cares to look, feel free. 

https://www.dropbox.com/sh/t5wdmq8x9i2jr5w/AAAcmwcDAHzIiZdQF2K-Y_iua?dl=0

[ollypenrice]

It's difficult because, like M42, it has a very high dynamic range. Most imagers now want to pull out the deep nebulosity seen in the best images and they also want the stars under control. It is, furthermore, a broadband target so there is no anti-LP help available from an Ha layer. And anything blue challenges rerfractors and coma correctors and focal reducers because of the short wavelength light.

Apart fom that it's a piece of cake!!! 

Olly

[nightster]

It's difficult because, like M42, it has a very high dynamic range. Most imagers now want to pull out the deep nebulosity seen in the best images and they also want the stars under control. It is, furthermore, a broadband target so there is no anti-LP help available from an Ha layer. And anything blue challenges rerfractors and coma correctors and focal reducers because of the short wavelength light.

Apart fom that it's a piece of cake!!! 

Olly

"Piece of cake" is laugh out loud funny.   I did the Lum several months ago and I liked the detail I obtained. I really tried to focus on getting good blue data this last attempt. I shot Blue at zenith down till it went below the neighbors house the first night, then filled in some G and R the next night. So I am glad that I am not the only one who struggles with this. 

[Tim]

Faster scopes do seem to make it easier, allowing shorter exposures and still gathering nebulosity. I tend to find anything over 5 mins with most scopes starts to give you issues.

So, fast scopes, dark skies, good transparency, and a session while m45 is near its highest altitude......too much to ask???? :)

[ollypenrice]

Ideally you should shoot blue only across the zenith. Once at low altitude it suffers more than the other wavelengths from atmospheric scattering (which is why the sky is blue and the sun is redder when near the horizon.)  Of course, reality does tend to get in the way of any advice beginning with 'ideally...'

 

For HDR targets you might find this very useful.  http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM  In this case the author is using different sub lengths but the system will also work on different stretches of the same data.

Olly

[sternenben]

Okay, I have to admit that I'm out of my depth for processing your image.  I haven't tried processing LRGB images before--I've been using a DSLR.  I tried a few different tutorials for combining the channels you uploaded, but couldn't get the combined image's colors to look right (I got the nebula the right color, but the background had a tinge and some gradients I couldn't get rid of).  Maybe someone else can give it a go?  

[nightster]

Thanks for trying. This target has been my nemesis for years.  That blue channel has stacking errors. Probably due to the focus shift I've been dealing with. I got another piece of hardware coming soon to help alleviate the focus drift bloating I'm seeing.  I will admit, I cheat and try to sleep.  

This hobby is crazy: the better you get the more you know you stink.