Star Field Buldge - Star Trail Arcs

[Aussie Dave]

The Milky Way bulge with star trail arcs. Not true arcs.

Nikon D3100, standard 18mm lens, ISO 1600, 85 x 20seconds, stacked in RegiStar (Combined images on Max setting + Image Weights on Absolute), reduced noise in PDN.

[Daniel-K]

dave that looks great. when you adjust your levels try not to bring the black in too much as it clips the data.

you see your histogram is way left and the black point is clipped. try and keep the left hand edge of the histogram off that left point.

[Aussie Dave]

Thanks Daniel. I've lost a lot in the pic but I do like a black sky. I realise the sky isn't actually black, it's a personal thing if I go too far it blows out those little nebs and close bright stars and clusters.

I expected much more from 28 minutes of total exposure time. I haven't seemed to have gained much from a single exposure of 20 seconds, I did remove the UV filter too. I tested all the combined image setting in Registar and they're all much about the same with the end result. I'm a little puzzled at the moment, maybe I'm missing something.

Also I didn't think there were green stars.

[Daniel-K]

dave can you post a raw image unprocessed 

[Aussie Dave]

Oh no, single exposure jpg's... yeah I know :/

Stacked images have been converted to png from Registar.

Nikon's have a similar RAW file format,  NEF (RAW) but from what I've read NEF still has some file compression. The only reason I shoot in jpg's is it transfers the file to memory card much quicker. For NEF to transfer to memory card takes a very long time due to the much larger file size.

I had another edit and I'm getting deja vu with this. I actually like the more bluer whiter colours, much the same as when you look at the Milky Way but with enhanced features. It's too noisy though at 1600 ISO.

 

Below is an unedited png combined stacked pic straight from RegiStar.

 

Honestly Daniel I can see no visual difference from an 85 image stack compared to a single exposure. I can post an unprocessed single jpg shot if you want to have a look at it and compare.

[Aussie Dave]

One object I only noticed today while processing that I've never seen before even in my scopes for visual is towards the bottom left hand corner, the brightest object there.

The other good thing is I can now find the area where the Southern celestial pole star is located from my (semi) star trail ark pic. By eye visually I can see no stars in that area due to the light pollution along the south coast ocean side. But it's located just above the house roof.

[Aussie Dave]

Last image edit. strange as this may seem but I softened the image quite a lot which got rid of some noise and brought out more fuzz. I can now notice some rainbow colour effects in it, think I've over done it again. Is this what I'm after?

[Daniel-K]

the 

1 hour ago, Aussie Dave said:

Oh no, single exposure jpg's... yeah I know :/

Stacked images have been converted to png from Registar.

Nikon's have a similar RAW file format,  NEF (RAW) but from what I've read NEF still has some file compression. The only reason I shoot in jpg's is it transfers the file to memory card much quicker. For NEF to transfer to memory card takes a very long time due to the much larger file size.

I had another edit and I'm getting deja vu with this. I actually like the more bluer whiter colours, much the same as when you look at the Milky Way but with enhanced features. It's too noisy though at 1600 ISO.

 

 

 

[Daniel-K]

for me this is the most natural one. the only downside is that your using a NIKON they are no known for good night time photography hense the noise.  did you try Deep sky staker?

[Daniel-K]

i had a go at processing it for you in CS6 you have some nice structure and a big nebula in the middle honestly its not a bad image you just need better SNR longer subs would help

[Aussie Dave]

I do have DSS installed on my tower PC Daniel and I'm sure I tried it once. I'll give it another go tomorrow. Thanks heaps for your help and input

[happy-kat]

With 85 lights a stack I would think would sing.

Do you take bias and darks or only lights?

[Daniel-K]

58 minutes ago, happy-kat said:

With 85 lights a stack I would think would sing.

Do you take bias and darks or only lights?

not with 28 minutes of exposure time. its weak SNR His subs where only 20secs long it would be a lot better if they where 60secs

[happy-kat]

But we have to work with what we have (tripod/kit) I assumed that 85 images would generate a bit more than a single image. Is this only if they are raws?

I could only dream of pulling that much from my garden sky as Dave does.

[Daniel-K]

Dave just a thought does the nikon camera have a noise reducing setting?  I know the canons do. If it does you want it switched off.

[Aussie Dave]

9 hours ago, happy-kat said:

With 85 lights a stack I would think would sing.

Do you take bias and darks or only lights?

That's what I expected Happy-Kat and was hoping features would pop out but nope, it never happened and never will with this camera or how I'm doing it atm.

No bias or darks however I did think about doing darks that night. Bias and flats I'm not sure about them yet. I didn't think I would've needed them with just over 28 minutes total exposure time.

8 hours ago, happy-kat said:

But we have to work with what we have (tripod/kit) I assumed that 85 images would generate a bit more than a single image. Is this only if they are raws?

I could only dream of pulling that much from my garden sky as Dave does.

Yes just on a tripod and taken in jpg format. Would I gain much more in Nikon NEF (RAW) format?

From now on I will only take one 20 second shot. There's no point in doing XX amount more, it's a waste of time and effort with this camera. I was looking in to buying an ultra wide angle lens to perhaps bump up the exposure time to 25-30 seconds but it's not worth the expense. The D3100 sensor is quite poor in both image quality sharpness and night exposures.

Happy-Kat you could probably get better results than me on one of your good nights there to what I'm using. The conditions here are quite good for The Milky Way. About 3am it's almost directly overhead near the darkest part of the sky with the tail end of dust clouds trailing off towards the Eastern horizon with that horizon having the least amount of light pollution. I'd like to do a mosaic, just not with this camera.

I'm off to have another go with Deep Sky Tracker.

[Daniel-K]

Dave Definitely use RAW next time you should get a better result.

[Aussie Dave]

ok last edits, this time from Deep Sky Stacker. Setting on default 80% good frames (could of done 100%) 65 frames, 21 minutes 40 seconds. The bulk of the editing was done in RAW Therapee, finished in PDN. Below are 2 different edits from PDN from the same pic from RAW Therapee.

On the Deep Sky Stacker website it explains some of the basics of ISO settings with photons, theory, stacking examples, lights darks bias flats etc in quite basic terms, a good read with much more info and links within those pages.

[happy-kat]

That's got more in it the first of the two.

Bias, stick lens cap on, set fastest shutter speed bang 20 out.

Sharpness, I find the camera is let down with the kit lens can't see your Nikon being any different. See if in your local second hand places you can get an old m42 lens to try 50mm range you'll need a mount converter adaptor.

[Aussie Dave]

Apparently the Nikon D3100 does have a noise reduction setting, trying to find it in the settings,. By default it is set to ON for longer exposure times. I'll try NEF (RAW) next time but I do need to do longer single exposure times to capture the fainter detail/photons on the sensor for each frame.

 

Noise reduction was off.

The standard 18-55mm zoom lens isn't great, at 18mm the center of images are ok but towards the outer edges you can notice CA.

[happy-kat]

Stopping the lens down could help there and improve star shapes if you found them iffy at the edges

[Daniel-K]

Much better dave 

[Daniel-K]

bet your pleasedwith that results 

[pipnina]

I have the D3200, turn on "Distortion correction" if the d3100 supports it. Also, the lens has very bad effects at the edge unless you stop down slightly (if you're at 18mm try f 5.6, if you're at 55mm try f8)

[laudropb]

Very nice to see a view of the Milky Way from Scotland.