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Capturing IFN from Bortle 5 with ASI1600MM

astrophotography imaging
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#1 Jon2070

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Posted 20 February 2019 - 05:08 PM

There is some clear weather forecast in a few days and I'm going to attempt M81 & M82 LRGBHa with my new(ish) ZWO ASI1600MM-Pro, I imaged them around this time last year with a DSLR.

 

I'd like to try to get some of the IFN and in other posts it looks as though it's possible from Bortle 5.

 

Would a good approach be HDR; shoot usual L exposures to get a median ADU of 400 at 0 Gain, probably around 30s from experience, but then get some longer L exposures for the IFN?

 

Is it also worth getting longer exposures for R and B as well as the usual for median ADU of 400? I read that IFN is faint red emission and faint blue reflection.



#2 tolgagumus

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Posted 21 February 2019 - 02:02 AM

When you are in light pollution using LRGB filters the camera is almost irrelevant. Your biggest challenge is the shot noise from the LP. If you want to see some IFN I would guess you will need about 15-20 hours integration at minimum. You should wait for new moon. The other thing I would suggest is to skip the L and only shoot RGB and create synthetic L from the RGB. This is what I used to do when I shot from home but I was in more like bortle 4. 


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#3 TareqPhoto

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Posted 21 February 2019 - 03:11 AM

Hopefully to see your results, i am in Bortle 8 and i still don't know how or when to use my LRGB, i tried it only on M42 and M45, not that great results, but it was only short exposures anyway, and those 2 targets are mostly away from the heavy light pollution dome a bit, but i need to try with galaxies as they are mainly within that LP dome.

 


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#4 Jon2070

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Posted 21 February 2019 - 04:38 AM

When you are in light pollution using LRGB filters the camera is almost irrelevant. Your biggest challenge is the shot noise from the LP. If you want to see some IFN I would guess you will need about 15-20 hours integration at minimum. You should wait for new moon. The other thing I would suggest is to skip the L and only shoot RGB and create synthetic L from the RGB. This is what I used to do when I shot from home but I was in more like bortle 4. 

Thanks Tolga, I'm hoping to do the broadband bits before the Moon rises and do the Ha thereafter. I've read quite a bit about making synthetic lum from RGB and I think that this is the way forwards as otherwise I end up with a crazy amount of L files as they are so short.



#5 Ladyhawke

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Posted 21 February 2019 - 05:20 AM

I know this is not the best image, I was having issues with my equipment at the time but it was shot with LRGB from a Bortle 5 (downtown, small town). I also don't know why I didn't put the acquisition time on Astrobin, I usually do but I know that with this equipment I usually shoot 10x900 sec for each filter. I hope this helps!

 

get.jpg?insecure


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#6 calypsob

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Posted 21 February 2019 - 11:20 AM



There is some clear weather forecast in a few days and I'm going to attempt M81 & M82 LRGBHa with my new(ish) ZWO ASI1600MM-Pro, I imaged them around this time last year with a DSLR.

 

I'd like to try to get some of the IFN and in other posts it looks as though it's possible from Bortle 5.

 

Would a good approach be HDR; shoot usual L exposures to get a median ADU of 400 at 0 Gain, probably around 30s from experience, but then get some longer L exposures for the IFN?

 

Is it also worth getting longer exposures for R and B as well as the usual for median ADU of 400? I read that IFN is faint red emission and faint blue reflection.

IFN sits right above the noise floor, alot of people will pick it up in a light polluted area but do not know its there.

Also, if you are not taking phenomenal perfect flat frames, it will never work. If you hide vignetting or background issues by keeping the background extremely dark, you will never reveal the IFN.

Study the region that you want to shoot closely and pick out the brightest part of the IFN, try to image it near Zenith, and make 100% sure that you have good transparency or its going to be much more difficult, having light pollution is one thing but trying to image through bad transparency with light pollution is a disaster, you will pick up the galaxies but not the IFN.

The challenge is 50% processing and 50% acquisition conditions.

 

The area near the star 24UMa is pretty bright, I believe the Mandel Wilson catalog refers to it as the Volcano nebula.

I think you could pick this up in a light polluted area under ideal conditions, the image below was captured at a Darksite, but I

am pasting this in to point out the brighter portion of this nebula.

 

33058607552_3b7e4ff4b4.jpg

M81 and M82 IFN from Monochrome 60d by Wes Schwarz, on Flickr


Edited by calypsob, 21 February 2019 - 11:32 AM.

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#7 Jim Waters

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Posted 21 February 2019 - 01:16 PM

IMHO the key to capturing IFN is...

 

- Dark sky site

- Many long deep exposures - Several or more hours

- Dithering

- Very good Flats


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#8 Jon2070

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Posted 23 February 2019 - 04:24 PM

I know this is not the best image, I was having issues with my equipment at the time but it was shot with LRGB from a Bortle 5 (downtown, small town). I also don't know why I didn't put the acquisition time on Astrobin, I usually do but I know that with this equipment I usually shoot 10x900 sec for each filter. I hope this helps!

 

get.jpg?insecure

Thank you Samara, that is a great image and useful to know.

 

IFN sits right above the noise floor, alot of people will pick it up in a light polluted area but do not know its there.

Also, if you are not taking phenomenal perfect flat frames, it will never work. If you hide vignetting or background issues by keeping the background extremely dark, you will never reveal the IFN.

Study the region that you want to shoot closely and pick out the brightest part of the IFN, try to image it near Zenith, and make 100% sure that you have good transparency or its going to be much more difficult, having light pollution is one thing but trying to image through bad transparency with light pollution is a disaster, you will pick up the galaxies but not the IFN.

The challenge is 50% processing and 50% acquisition conditions.

 

The area near the star 24UMa is pretty bright, I believe the Mandel Wilson catalog refers to it as the Volcano nebula.

I think you could pick this up in a light polluted area under ideal conditions, the image below was captured at a Darksite, but I

am pasting this in to point out the brighter portion of this nebula.

 

33058607552_3b7e4ff4b4.jpg

M81 and M82 IFN from Monochrome 60d by Wes Schwarz, on Flickr

Thanks, very nice image depth, that is useful to know.

 

IMHO the key to capturing IFN is...

 

- Dark sky site

- Many long deep exposures - Several or more hours

- Dithering

- Very good Flats

Thank you Jim


Edited by Jon2070, 23 February 2019 - 04:24 PM.


#9 Jim Waters

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Posted 23 February 2019 - 05:52 PM

IFN sits right above the noise floor, alot of people will pick it up in a light polluted area but do not know its there.

Also, if you are not taking phenomenal perfect flat frames, it will never work. If you hide vignetting or background issues by keeping the background extremely dark, you will never reveal the IFN.

Study the region that you want to shoot closely and pick out the brightest part of the IFN, try to image it near Zenith, and make 100% sure that you have good transparency or its going to be much more difficult, having light pollution is one thing but trying to image through bad transparency with light pollution is a disaster, you will pick up the galaxies but not the IFN.

The challenge is 50% processing and 50% acquisition conditions.

 

The area near the star 24UMa is pretty bright, I believe the Mandel Wilson catalog refers to it as the Volcano nebula.

I think you could pick this up in a light polluted area under ideal conditions, the image below was captured at a Darksite, but I

am pasting this in to point out the brighter portion of this nebula.

 

33058607552_3b7e4ff4b4.jpg

M81 and M82 IFN from Monochrome 60d by Wes Schwarz, on Flickr

Real nice image.  How do you do the Mouse Over on Flickr?



#10 calypsob

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Posted 23 February 2019 - 06:58 PM

Real nice image. How do you do the Mouse Over on Flickr?


Add it to the astrometry group, they will plate solve the image


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