NGC 1976/1982/1977 and friends

[seeker372011]

This is my first attempt at Orion this season. The plan is to wait for it to get a little higher in the sky and keep adding information over the course of the summer. This is a stack of a 10 minute and a 20 minute exposure at ISO 400 from suburban Sydney using a Astronomiks CLS filter. Scope- ED80, Camera- 300D. The core came from a short exposure taken last summer.

Calibration in IRIS, Processing in Photoshop.

Very much a work in progress. Hope to improve on this through the summer by adding more exposure.

[atalas]

Looking very nice Narayan , what mind blowing colours you have there mate ! looking forward to seeing more of It.

[jjjnettie]

Nice work, look forward to following its progress.

[h0ughy]

wow, I really really like this one! Excellent!

[iceman]

Wow Narayan! Stunning shot!

[davidpretorius]

can i have your mount?????

top work, as looking at this again this morning, a lovely piece of the sky.

i am only just starting to get my head around iris!

[Itchy]

Nice work. I look forward to more.

The background is very dark and I suspect that there is even more faint detail that you could extract. 20 min exposures is only a dream for me. Any problems with noise at that length? I might also suggest ISO 800, particularly with that filter. What is your estimate of the extra exposure needed when using it?

Cheers

[RB]

Wow Narayan,

That's a great shot, can't wait to see the final one.

Just a quick question, I asume you are taking this at prime focus. If so how is the CLS filter inserted in this setup?

:help:

[seeker372011]

Thanks for the nice comments, folks.

The filter does allow much longer exposures from a light polluted location, but brings associated processing challenges

Noise is a HUGE problem..despite applying dark frames..that's the main reason I think lots more exposure is needed... The other big processing challenge when using the filter-and I now wish I had got a 2 inch instead of a 1.25 inch filter-is vignetting which my flat fields minimise but do not eliminate.

The filter seems to split the three channels..so the histogram of the red channel stays way over to the left, while the other two channels move to the right

Without the filter the histograms stay fairly closely bunched together..

I dont have a good estimate as to how much longer the exposure has to be to bring the red to the same point (of course the other channels would get completely saturated). I have been experimenting with combining relatively short-5-8 minutes and longer exposure-usually 10 minutes. This is only the second time ever I have gone as long as 20 minutes..I didn't believe it wouldn't white out


I have actually never tried ISO 800. At ISO 1600 just doesnt work except for very very short exposures from my location even with the filter

[seeker372011]

I use a camera adapter mounted on the T adapter and screw the filter into the camera adapter..hope that explains it well enough?

[RB]

Thanks Narayan,
but what size filter are you using? my 2" filters are too large for my camera adapter/T-mount combo.
I use the camera adapter that came with the Orion ED80.
The only way I can use these filters is if I screw them into my 2" diagonal first and then attach the camera. It's not the ideal setup.

:help:

[seeker372011]

ah, I use a 1.25 inch filter..but pay the price of heavy vignetting :)

[Itchy]

Using only two exposures would not be helping the noise. There should be a better S/N ratio with more sub exposures. Your right about the 1.25"



Interesting. I have just received an Baader UHC-s filter (I think Scott uses one) and i am keen to see the effect on the histogram.


800 would be worth a shot.

Cheers