Orion got hunted!!!

[MGTechDVP]

Hi All,

Just sharing the latest image of the Orion Nebula in narrowband I was able to get in between the cloudy weather.

Each image was taken using a full spectrum astromodded Canon 40D and Celestron NexStar 8SE on a CGEM mount. Each channel comprises of 6 x 1800s at ISO200 for the faint nebulosity and 10 x 300s at ISO200 for the core.

The Hubble image comparison was color adjusted to match the Hubble image.

Thanks for looking.

Mariusz

[SimmoW]

Nice & good comparison pics. Wow, 30 min subs with an SLR! Is it cooled?

[rmuhlack]

curious as to your setup for narrowband with a DSLR ? are you using clip in filters, or do you have a filterwheel setup in front of the camera?

[ZeroID]

300 secs is 5 mins, still impressive !!

Awesome pix btw Marius, well done.

[Rod771]

Brent, Simon was referring to this. :)



Nice image Marius :thumbsup:

[MGTechDVP]

Thanks for the great feed back guys,




My DSLR is not cooled it only has the IR filter replaced with a clear piece of glass... During the exposures, in Orion and the Horsehead previously, APT reported the the sensor was at 21 - 26 degrees C and granted there is a fair amount of noise on the subs.

I found that when converting the RAW CR2 subs in Photoshop RAW converter the plugin, as opposed to using DPP, it does a really good job of removing the noise. I did the same to the dark frames and subtracted those in Nebulosity 3, resulting in a very clean sub image...

Attached are two JPG converts from TIFFs converted from CR2 in DPP and PS CS4, no noise reduction other than what the plug in did by default.




I use a filter wheel before the DSLR, and the filter sizes I use are the 1.25" type... it does not cause as much of a vignetting effect on a APS-C camera as a lot of forums claim it does. Attached a pic of the setup I used to get the subs on this orion nebula pic.

Clear skies,

Mariusz

[SimmoW]

Thanks for your detailed reply Mariusz.

What model filter wheel did you use?

Have you compared individual shots at say, 10, 20 and 30 mins? I only ask as Shot noise might be excessive beyond 10 mins (or so I've been told!), you might get better results doing more subs of say 20 mins. Just a suggestion to try.

Either way, you're pushing your DSLR to the limit, lovely work

[MGTechDVP]

Thanks Simon,

before plunging into 30 min subs I did experiment with 15 min, 20, 25 and 30 minutes and I found that the temperature of the sensor was very similar in all.. even the noise level was not that much higher in the 30 minute sub as in the 15 minute.

I'm thinking of targetting a very faint object, such as the outer nebulous whisps of the Helix nebula but perhaps going for a hour sub... ISO100/200 just out of curiosity...

I'm thinking that the length of the sub exposures would be dependent of how of a faint object I'm imaging. That said I do seem to get crisper, higher detailed images when using lower ISO sensitivities... although not much difference between ISO200 and 400.
I'm thinking that the longer subs at ISO200 would pick up more fainter detail as opposed to half the time at ISO400 due to the sheer time that the sensor is collecting real photons per sub... Then there is also the balance of how long to expose before the frame gets over exposed due to ambient light... hopefully that is not a issue with narrowband, as I have found so far. With visible light at my location 10 minutes is about the limit of a sub at ISO100.

The Filter wheel I use is the Orion filter wheel with openings for 5 filters... not electronic, just a standard manual type... with auto guiding working so well, I thought I'd leave a few things where I can still be a part of the hobby, namely filter changes and focusing.

Mariusz