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 Post subject: Startrails Take 2
PostPosted: Sat Oct 18, 2008 11:48 am 
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Joined: Sat Oct 11, 2008 8:27 pm
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Location: Bristol, UK
OK, this is my second recent attempt at startrails. I wanted to include some more foreground interest. I'm not sure this shot is 100% successful but it confirms to me that my technique is working. Now I need to wait for another clear night and find some better objects for foreground interest

Image

This is made from 145 light frames each 25sec long ISO 800 and one dark frame. They were then stacked using the free startrails software. I then had a play with IRIS to remove the gradient from city lighting and finished the processing in PS.

Thoughts and comments welcomed.

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 Post subject:
PostPosted: Sat Oct 18, 2008 9:12 pm 
It looks damn cool man! Really.
Can you give a more detailed info about how it was shot / processed?


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 Post subject:
PostPosted: Sun Oct 19, 2008 8:27 am 
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Sure 0eyvind, and thanks for the comments.

This shot was taken with my sigma 10-20mm set at 10mm. I set the camera to manual and dialled in a 25sec exposure at f3.5 and set the ISO to 800. Then I set up my intervalometer so the camera would take 145 shots one after the other. After the last frame was exposed I took two more additional frames. The first was so I could paint the tree with light. The second was with the lens cap on to act as a dark frame.

Once acquired I then batch converted the RAW files in PS and used a free piece of software (found here) to automatically combine all the frames. Once combined I tweaked levels and curves in PS and finally used the gradient mask in IRIS (found here) to remove some light pollution.

And that's it.

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 Post subject:
PostPosted: Sun Oct 19, 2008 7:35 pm 
Thanks. Very interesting. Does your camera has buil-in intervalometer?
I should try that one day :D


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 Post subject:
PostPosted: Sun Oct 19, 2008 9:16 pm 
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Joined: Tue Feb 05, 2008 9:14 am
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Location: Netherlands
Thanks for sharing. Now, what's an intervalometer and how does it work? I wanna try this too :P

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 Post subject:
PostPosted: Mon Oct 20, 2008 7:14 am 
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The D200 has a built in Intervalometer but you can buy them separately and I think they plug into (and also act as) a cable release.

An intervalometer is basically something which allows you to set intervals (in this case 26sec) and then define how many intervals for the camera to use and how many shots to take in that interval.

So in this case the interval was 26sec and I set my camera to take 1 shot each interval (because the shutter speed was 25sec and only one shot could physically be taken) and then told the camera to take 145 intervals. To illustrate it further you could set the interval to 60sec and set the shutter speed to 1/500s (i.e. during the day) and then tell the camera to take 20 shots each interval (because the shutter speed is fast enough.)

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 Post subject:
PostPosted: Wed Oct 22, 2008 2:07 am 
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Location: Queenstown, New Zealand
Hi Lee, nice capture - did you choose 25 seconds becuase the frame would overexpose otherwsie, or is that you didn't have a cable release?

You could alternatively try a lower sensitivity and even quite a small aperture with a much longer single exposure - although of course run the risk of your battery going. It's a great result you've got anyway and I'd never have thought of doing it with multiple shots and an intervalometer.

As for a critique, I'd try and scout out a position which avoids overhead lines, but still they're not that obtrusive here...


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 Post subject:
PostPosted: Wed Oct 22, 2008 7:15 am 
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Hi Gordon, thanks for the comments.

The reason I chose 25secs was because it was the only shutter speed I could use to get the intervalometer to work reasonably well. With a 30sec shutter speed I needed to set the intervalometer to 32sec which mean a 2 second gap and (having done this before and accidentally left the self timer on) you get gaps between the trails. In terms of initial setup I also chose a shorter shutter speed and combined shots to minimise the chance of noise which is more prominent with DSLR and long exposures.

This shot was done with the aperture fully open, but I might try it with my 50mm f1.8 and play about with sensitivity. As for the location I definitely need to find a better spot as you say and try and avoid overhead power lines.

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