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NGC 2244 - fun with noise...

Alveprinsen

By Alveprinsen
in Getting Started With Imaging

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Alveprinsen

Alveprinsen

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Lights: 42 x 10 minutes

Darks: 18 x 10 minutes

Bias: 30

Flats: 30

ISO: 1600

Total exposure time: 7 hours.

NGC2244smallJPG.jpg

The noise is a real killer, but at least I was able to image this object in order to get the experience with it. Now I know how to attack this object as soon as my new camera arrives. :)

PS: Is it just me, or is my flatfield panel creating "bands" across the image? If you zoom out and look at the picture from a distance, it looks as if the flat field frames were not completely uniform when taken.

I might have to go back to using laptop screen for flats if this is the case. :( And that panel was expensive too...

Sincerely, Alveprinsen.

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Alveprinsen

Alveprinsen

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... I agree that there seems to be some banding visible

Perhaps I am using the panel wrong?

When I do my flatframes I hold the flatfieldpannel up against the dew-shield on the Evostar 80ED Pro... I wonder... perhaps I am supose to hold it "in front of it" but at a few cm distance, and not up against it? ...

Anyone else have any experience with these flatfield panels?

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Alveprinsen

Alveprinsen

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...Use Gradient  Xterminator and then just a slight use of the color slider in your noise reduction software. Works for me.

Hmm, I still havent aquired that little piece of software.. or rather, plugin... I will try to actually do it... soon.. :)

I just pointed my scope at NGC 2264, but couldnt see Rubbish even with a insane ISO setting (High2) and 30 sec exposure. I could see that little cluster-thingy of stars though, so I guess having that in the middle of my FOV will do the trick. :)

The moon is like 3/4 full too, but... it will be below the horizon at 02:15 AM.

I set the camera to do 38 10 minute exposures, so I'll check out the scope at 6AM and do flats and bias before setting it to do 3-4 hours of darks... The temperature wont change much.. its only like 0 degrees atm. :)

Anyhow, rant aside.. I'll take another look at that plugin. I'm just super lazy when it comes to buying stuff I dont like... need right away...

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Astrosurf

Astrosurf

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Isn't NGC 2264 an emission neb, like the Rosette? If so, you would need a modded DSLR or dedicted imaging camera to collect the infra red data. It'll be very faint otherwise. I assume you're using an un-modified camera which is why there's not that much red in your Rosette even with such a large exposure time?

It's a lovely image!

Alexxx

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Alveprinsen

Alveprinsen

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Isn't NGC 2264 an emission neb, like the Rosette? If so, you would need a modded DSLR or dedicted imaging camera to collect the infra red data. It'll be very faint otherwise. I assume you're using an un-modified camera which is why there's not that much red in your Rosette even with such a large exposure time?

That is correct. Unmodded indeed! :)

Luckily I've got a new modded Canon otw... its a bit long delivery time on it, so in the meanwhile I am riding it out with my crappy Nikon. :)

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Alveprinsen

Alveprinsen

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A good job, however 7 hours using your "on the way" modded camera will blow your socks off. This specific target (amongst many others) really benefits from a modded camera.

Dude, I am having a hard enough time waiting as it is, without you having to make it harder! :p

Man... I'd love to have my socks blown off right now...

Anyhow, clear skies tomorrow, and what.. full moon? Or close to it... Gonna slap a 2x Barlow on my 80ED and do 1200 shots with my crappy Nikon and finally test that planetary-stacking thingy in registax or whatnot... ;)

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Astrosurf

Astrosurf

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Anyhow, clear skies tomorrow, and what.. full moon? Or close to it... Gonna slap a 2x Barlow on my 80ED and do 1200 shots with my crappy Nikon and finally test that planetary-stacking thingy in registax or whatnot... ;)

Good luck!. We're off comet hunting at 4am!

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lensman57

lensman57

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Lights: 42 x 10 minutes

Darks: 18 x 10 minutes

Bias: 30

Flats: 30

ISO: 1600

Total exposure time: 7 hours.

NGC2244smallJPG.jpg

The noise is a real killer, but at least I was able to image this object in order to get the experience with it. Now I know how to attack this object as soon as my new camera arrives. :)

PS: Is it just me, or is my flatfield panel creating "bands" across the image? If you zoom out and look at the picture from a distance, it looks as if the flat field frames were not completely uniform when taken.

I might have to go back to using laptop screen for flats if this is the case. :( And that panel was expensive too...

Sincerely, Alveprinsen.

Hi Alve,

A very good effort, well done. I await your results with the modded cam when  it arrives. My EL Panel has given up the ghost only after 2 months. The banding could be due to the high frequency of the EL panel and the camera's exposure settings,  I believe these work around 1000 Hz so this could be the cause. Some banding oise could be removed in software.

Regards,

A.G

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Alveprinsen

Alveprinsen

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Hi Alve,

A very good effort, well done. I await your results with the modded cam when  it arrives. My EL Panel has given up the ghost only after 2 months. The banding could be due to the high frequency of the EL panel and the camera's exposure settings,  I believe these work around 1000 Hz so this could be the cause. Some banding oise could be removed in software.

Regards,

A.G

Actually, I emailed Gerd Neumann (whom  Ibought my flatfield panel from) about this banding, and he explained to me that this happens as a result of too fast shutter speed.

I might need to add a neutral density film to the panel, because at 1/180 sec shutter speed, the histogram is "in the middle" as it is suppose to be.

Do I HAVE to use the same ISO setting btw? If I could lower the ISO from like my regular 800 to say 400 during flatfields I could lower the shutter speed and get rid of the banding... But I dont know whether or not this would be counter productive or not....

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