Orion nebula attempt

[JB80]

I haven't had  the Polarie out for quite a while so I'm incredibly rusty with this widefield lark and even more so with the processing.

My first attempt for the night was M45 but that didn't turn out very good, the only thing I can think of is as I did my darks last the temp must of changed too much between them.

The Orion nebula did come out alrightish though, still a lot of red noise but at least it's not streaking all over the place.

I only took lights and darks as my battery went but did get a good number of darks, will bias help with the red noise or do I try and handle it in processing?

It was also the first real time I have used the CLS filter despite owning it for years.

This was 64, 59 second subs 63 darks.

ISO 800 at f8.0

Orion nebula by Jarrod Bennett, on Flickr

[Pete Presland]

certainly very noisy, but im sure you can help it in processing. There some very nice detail there, is that a little hint of the Horsehead nebula on the right?

[JB80]

Thanks Pete!

Yeah I believe there is a hint of the Horsehead, the one method though that I was trying to deal with the noise would of wiped the Horsehead out so I tried to leave it.

[symesie04]

Don't think the problem is noise in the red Chanel. There is some general noise but suspect this maybe processing relics as your subs are quite short. The red in the image I think is all part of Barnards loop and should processed into the image. On the other hand the green channel is a bit strong and causing a colour cast, you might want to try and get rid of that. Nice image though.

[Psychobilly]

How and When did you take your darks...?

Was i it at the ends of the session?

Have you tried stacking it without the darks?

I would give it a go and see what happens... 

Peter...

[JB80]

I took the darks after the run of subs so yeah at the end, I had taken nearly an hour on the Plieades then an hour on Orion so the camera was running for 2 hours. I guess that doesn't help with the sensor temp.

I did it with the lens cap on.

I will give it a go now without darks and see what happens.

[Psychobilly]

I know I haven't posted a new image for several years but used to be quite active with DSLR's and found that mismatched darks were often worse than using no darks...

I used a mixture of natural "dithering" - Sub pixel drift between images, Kappa Sigma Stacking with plenty of lights  and "Cosmetic"  Hot and Cold pixel removal in DSS ...

Peter...

[JB80]

Hmm, well no darks was a lot worse. I just stretched it a bit but the noise is horrible and streaky now. I have changed the settings now and am trying again.

Interesting that dithering comes up again, it seems it may be a solution but how do I get that to happen with the Polarie, just sit outside and nudge the tripod manually or is there a better method. It's odd I never had that issue before but has started the last couple of seasons.

[Psychobilly]

Looks like you 450D behaves substantially differently from my 1000D - There's quite a bit of "structure" in that image as well as the noise... 

Dithering is a small shift in RA and DEC between frames  so that Hot and cold pixels will change position relative to the starts which will be "aligned" in the stacking process.. Don't really know how you would achieve this with the polarie

[JB80]

I am starting to suspect my sensor may be on the way out or there is just something wrong with it, in fact I have suspected this for quite a while now. I may be wrong or just looking for an excuse for a new camera.

[JB80]

https://www.dropbox.com/s/2fbe55p7pcfgdhv/IMG_0881.CR2?dl=0

Here is a link to one of the raw subs, I had a play with it in PS but I don't think it's normal. Can someone tell me if it's what I should be expecting for a minute sub with a CLS in?

[Psychobilly]

So there was no Bias frames included in the Stack ?

If there weren't  - Take a load of Bias Frames  (around 30)  Min Shutter speed (1/4000s) Same ISO as the lights and with no light entering the camera and include them in the stack...

Peter...

[JB80]

No, I was planning too but the battery went flat.

I'll put the camera out and give it a try as well. Also trying the latest version of DSS.

[JB80]

Adding bias didn't do much either but I would feel better if I did them after taking the darks and subs.

From what I'm reading it could be heat noise from the camera so I don't suppose there is much I can do about that, maybe buy an adapter to run from mains. I'll try again when I get a chance.