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Old 30-03-2011, 05:51 PM
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leon
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Please assist with Star Trails of SCP area

Hi Guys, Alice and I are both well, and are still in South West WA, and enjoying every day as we travel along.

At the moment we are in the wide open spaces near Nannup, with blue skies for the last three weeks and ink black skies at night, the Milky Way just about casts a shadow.

Hence my post here.

I have done, and know enough, about Deep Space imaging, but have never done any star trails, and because the nights are so dark here I thought I might give it a go.

Could someone here please assist with the settings to take good star trails of the SCP region.

I will be using a tripod mounted Canon 5D, with remote, and Canon 50mm F/1.2L lens.

The question I ask is: ISO setting, lens F Number, amount of time for each exposure, and how many should I take to do a reasonable star trail, plus anything else that I might need to know.

Many thanks in advance.

Leon
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Old 30-03-2011, 06:01 PM
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In my trials I came accross this page http://www.startrails.de/html/software.html

I have not done any trails with it but it may give you some ideas.

Good luck!
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Old 30-03-2011, 08:11 PM
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Hi Leon,
Yep Nannup is a dark spot!
Here is one I did at work overnight. A fair bit of light, plane and satellite pollution here.
I also interrupted the shooting at one stage
Not the best, But I'll return to it one day.

Also some other shots on my photobucket album and a larger version of the photo below:
http://s937.photobucket.com/home/bartman691/index

The SCP one was with a D90, 800 iso, f/3.5, 10mm, 30 sec exp and 200 shots (auto wb). Processed with StarTrails and also made a small movie in Picassa- which I still need to work on-

oh and here is one of the frames as well...

Have fun!!!!!!
Bartman
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Old 30-03-2011, 09:38 PM
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Jakob and Bart, many thanks indeed, I plan to get out there to night and see how it all goes.

Leon
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Old 31-03-2011, 06:41 PM
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troypiggo (Troy)
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Bit of trial and error I guess. I'd start with ISO 400 or 800, close the aperture down a stop or 2 to maybe f/2 or f/2.8 to get the sharpest image although might get some diffraction spikes, and shutter speed will depend on conditions but 30 seconds might be a good starting point. Take many and stack them using the startrails program mentioned above. Don't use auto WB, set it to daylight so there's consistency between shots.
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Old 31-03-2011, 08:30 PM
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midnight (Darrin)
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Hi Leon,

Hope you are and have enjoyed the SW! Yes, the skies can be quite dark and we have been lucky with the endless summer here although we desperately need rain - it's pretty shocking here at the moment. Low-Mid 30's all next week too.

I have attached this link to a star trails I did recently with my 40D. I found that opening the aperture up too much (ie F4 or larger) caused rapid sky glow to accumulate so I now use F8. Then I can push out to about 4 minutes per shot before noise becomes an issue and then if you're lucky to have one of the programmable remote shutter release units, you can program it to take up to 99 shots to give nearly 6hrs of trails. Then use Startrails to stack them. BTW, make sure you take the dark frame at the beginning as it does make a huge difference. Startrails allows you to register a dark frame.

Good luck and enjoy the rest of your trip!

Cheers,
Darrin...

http://www.iceinspace.com.au/forum/s...ad.php?t=73663
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Old 31-03-2011, 08:51 PM
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Thank you again, guys, Darrin I have to agree mate the land is scorched as we drive alone, we are in Nannup for a couple of days and then we will spend time in Balingup, love that place.

We free camped for the last few days and it was so peaceful in a lovely bush setting, anyway I will try out your suggestions.

Leon
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Old 31-03-2011, 10:11 PM
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philiphart (Phil Hart)
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If you want a long star trail in one exposure, I'd use the following as a guide:

15 minutes, ISO200, f4
1 hour, ISO100, f5.6
4 hours, ISO100, f8

For the longer shots, you'll need to take a dark a frame as well! Long exposures really build up the hot pixels but they subtract out pretty well too (can use in camera dark frame subtraction but you need the battery power and the patience to wait the same time again).

If you do short exposures and stack them together, you'll inevitably have some gap (albeit small) between each segment, and the brighter exposure in each 'sub' tends to overexpose the stars so you lose their colour. I tend to prefer the first approach now.

Phil
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