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An unconvincing heart?

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#1 dciobota

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Posted 18 November 2018 - 12:06 AM

I've been in two minds about posting this pic of IC1805, because I'm not convinced what the pic shows is IC1805:

https://photos.app.g...7Hqk6biBCTq8oAA

 

I mean it's there alright, but I see other "nebulosity", especially blue (which is supposed to be O2) that I simply don't see in other images of the object, including narrowband.  As you can see in the info for the image, this was taken with the Canon EOS M50 (unmodified) from my Bortle 8-9 back yard.  So I had to do quite a bit of processing, from LP removal to stretching and some color enhancement.  But apart from LP removal, I don't think I've done anything that would introduce artifacts that look like in the image.  So I don't know tbh.  

 

 



#2 bobzeq25

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Posted 18 November 2018 - 12:18 AM

That's absolutely the Heart.  I platesolved your image, it's centered at 2hr 34.5min, 61deg 27 min.

 

I agree with you that the color is strange.  I downloaded your jpg, dialed the saturation way back, aligned the color channels, and did a bit of star reduction.  I'm not saying this version is good, but it does, somewhat crudely, show the Heart, as one might expect it to appear in broadband, with an unmodified camera.

 

Just not the best target for that camera, I fear.  You're obviously losing a ton of H alpha.

 

Autosave-mod-lpc-cbg-cbg-St V2.jpg


Edited by bobzeq25, 18 November 2018 - 12:46 AM.


#3 AKHalea

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Posted 18 November 2018 - 10:33 AM

Hey Daniel : I agree with Bob that an unmodded camera is not suitable to pick up much of HA nebulosity, especially in the Heart nebula. I had tried that same object with an unmodded camera about 2 years ago and got a similar result with bluish.pink tint dominating that area. So, there seems to be some blue/green H-beta and OIII emissions that is picked up by the unmodded cameras. 

 

I captured the same object (IC1805) a few days ago with an HA modded Nikon D5300 camera and a dual band HA-OIII filter which shows the usual predominantly red nebulosity. So I think the blue/green nebulosity due to OIII and H-beta gets overwhelmed by the very strong HA in most NB images of this object. However, I did find an interesting Ha-OIII-RGB image by Scott Rosen that shows a lot of this bluish tint in the Heart & Soul, in addition to the red HA (see here). Cheers ...... Anil


Edited by AKHalea, 18 November 2018 - 10:41 AM.


#4 dciobota

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Posted 18 November 2018 - 11:24 AM

Thanks Anil,

 

That was one of the images I also looked at for reference.  I think you're right, this camera cuts so much Ha that it lets the Oii overwhelm the image.  Tbh maybe I didn't give it a fair shake.  In APT the histogram showed the subs properly exposed, but photoshop shows the peaks at only about 20%.  I should have tried to overexpose a bit.  A darker site would definitely help here too.

Oh well, it was worth a try.  At least I verified the M50 works well with APT.  



#5 17.5Dob

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Posted 18 November 2018 - 09:36 PM

I have seen enough photos of the Heart Nebula taken with a plethora of stock cameras to know that is quite easy to capture it from a dark site, as are most nebula that are considered difficult. It's not your camera, or your processing, but your imaging site.

That said, a modded camera will make things much easier if you're having to deal with LP.. This is just 1 hrs worth of 45" subs, from my modded Nikon using a Samyang 85mm lens, trying to shoot between the trees that essentially obliterate the entire North sky in my Bortle 8/9 backyard


Edited by 17.5Dob, 18 November 2018 - 09:38 PM.


#6 dciobota

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Posted 19 November 2018 - 12:24 AM

I already know I can take good images of this object with a modded camera.  My whole point was the colors and nebulosity that I extracted from the image that I haven't seen in other images, so I was wondering if they were real data or artefacts of processing.  Anil rightly pointed out that's it's possible the blueish tints are OII overwhelming the little Ha collected.




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