Author Topic: [Theme] Show us your Star Trails!!!  (Read 10406 times)

Olivier

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Re: Show us your Star Trails!!!
« Reply #30 on: October 21, 2015, 10:50:28 »
Simone,

Thank you for the ref to the stacking software.
You obviously worked with a less than clean sky!

Jan Anne: I see several advantages for stacking vs one single long exposure frame.
1. Stacking allows you to work at higher ISO without the risk of over exposing parts of the picture. especially the sky itself will remain as dark as in one single short exposure.
2. Especially you can try star trails in the city, with quite luminous foregrounds. See the attached picture (many 20 second exposures) and imagine what it would be with a single 45min exposure)
3. in case something goes wrong during the process of acquiring the shots (unwanted plane, someone pointing a flashlight directly to the camera...), you can always eliminate the specific frame and keep the rest.

The nice thing is that the stacking is done in "lighten" mode, so only the brightest part of each shot are kept.
I agree that long exposures allow for better visibility of the foreground in dark areas. But with stacking, you always have the possibility to add a longer exposure to the mix, possibly with a higher ISO setting.

example taken near Paris, inside the city of Auvers sur Oise (where Jan Anne's fellow citizen Van Gogh lived his last days). This was another technical trial, stopped prematurely because of the arrival of an excessive amount of clouds.

simato73

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Re: Show us your Star Trails!!!
« Reply #31 on: October 21, 2015, 10:52:05 »
Great contributions everybody, thanks for sharing the amazing images and the techniques used to acquire them.

Just out of curiosity, why do some prefer the stacking method over the single exposure method?

For me personally I like the single exposures because they enable me to combine the star trails with the ambient light only seen at long exposures, like the orange glow of the campfire and the green remnants of the Northern Lights in my second shot and the yellow glow from the villages in the valley below in the third shot.

The very reasons you mention could push you toward a multi-exposure strategy in some circumstances.
For example when diffuse light (i.e. light pollution) is at levels where a very long exposure would lead to too light a sky, even at base ISO.
Also very long exposures accumulate noise. One could do long exposure noise reduction but that doubles the time the camera has to stay on, possibly exceeding the battery life.
(Alternatively one could shoot a dark frame and subtract it later, but I would not know how to do it)
On the other hand multi-exposures have their problems too. Joi9ning them without forming gaps in the star trails requires some tricks.
In my case I used many exposures mainly because I did not have a remote to keep the shutter open during the bulb exposure!
I had to resort to the intervalometer and the longest exposure available was 30s.
Simone Tomasi

Peter Connan

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Re: Show us your Star Trails!!!
« Reply #32 on: October 21, 2015, 19:35:07 »
Jan, mine were in the southern hemisphere, where there is no pole star. We have the southern cross, but it only points to the south, none of the stars are actually at the south axis.

I prefer stacking because most of my attempts at single exposures have been ruined by people with lights.

simato73

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Re: Show us your Star Trails!!!
« Reply #33 on: October 21, 2015, 22:17:18 »
Simone,

Thank you for the ref to the stacking software.
You obviously worked with a less than clean sky!


Thanks!
Yes, I did have quite a few drifting clouds that came after I had started the intervalometer.
Making a composite has alleviated the problem a little - it would be much worse if I had a single exposure - but I had to throw away many frames.
Overall the photo works as a proof of concept bu I have not managed yet a satisfactory one.
I live in a very cloudy and densely populated place so opportunities are incredibly rare for me (also considered that I have a day job and a family!).
Simone Tomasi

Øivind Tøien

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Re: Show us your Star Trails!!!
« Reply #34 on: October 22, 2015, 00:32:32 »
Inspired by this thread, I did my first somewhat successful stacked star trails last night. I had several failed attempts at making the interval timer of my D5100 work for 30 second exposures the previous nights. A little searching showed that a number of others had the same problems. I finally tried a 35 second interval as a search result suggested and that worked, but why? I also noticed that even with the interval that long, the time from the shutter closed until it opened again was only a couple of seconds. Then I timed the actual exposure and found it to be 32.3 seconds :o . So it seems that there are some inaccuracies in exposure timing, but not in the interval. Thus I have to set a longer time interval than expected to allow writes to the card and closing and opening of the shutter.

The image is more a proof of concept at a comfortable location right outside the door to my cabin, so not a very nice foreground. It was stacked from raw files with the free DeepSkyStacker in average mode with registering turned off. Even at 100% view there are no signs of dotting of the trails. This is probably because the fisheye makes each step very small and the 2.5 sec gaps cannot be resolved.



Nikon 10.5mm @ f/3.2, 120 exposures of 30 sec., ISO 100 (by accident).
Øivind Tøien

Jørgen Ramskov

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Re: Show us your Star Trails!!!
« Reply #35 on: October 22, 2015, 08:52:03 »
My lens collection is very limited and the wides I have is the Nikon 24-70mm. Will that do or should I not bother trying?
Jørgen Ramskov

Jakov Minić

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Re: Show us your Star Trails!!!
« Reply #36 on: October 22, 2015, 09:45:33 »
Jørgen, any lens will work. The photo I posted was made with a 300mm lens ;)
Your 24-70 is perfect :)
Free your mind and your ass will follow. - George Clinton
Before I jump like monkey give me banana. - Fela Kuti
Confidence is what you have before you understand the problem. - Woody Allen

Olivier

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Re: Show us your Star Trails!!!
« Reply #37 on: October 22, 2015, 10:02:40 »
Øivind: I am impressed by how high the pole is in your sky! Not surprising of course given your location.

Jørgen: 24 is wide enough. The key is not to get everything in, it is to compose well like for any kind of photography.

Asle Feten

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Re: Show us your Star Trails!!!
« Reply #38 on: October 23, 2015, 20:39:16 »
I had several failed attempts at making the interval timer of my D5100 work for 30 second exposures the previous nights. A little searching showed that a number of others had the same problems. I finally tried a 35 second interval as a search result suggested and that worked, but why? I also noticed that even with the interval that long, the time from the shutter closed until it opened again was only a couple of seconds. Then I timed the actual exposure and found it to be 32.3 seconds

It is easiest to just set the camera at serial and lock the remote release. If D5100 has such options...
There is no illusion, it just looks that way.

Jakov Minić

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Re: Show us your Star Trails!!!
« Reply #39 on: December 03, 2015, 11:21:37 »
Savin kuk, Zabljak, Montenegro.
An infrared long exposure D200 + 16/3.5 fish-eye.
Free your mind and your ass will follow. - George Clinton
Before I jump like monkey give me banana. - Fela Kuti
Confidence is what you have before you understand the problem. - Woody Allen

Peter Connan

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Re: Show us your Star Trails!!!
« Reply #40 on: December 03, 2015, 18:05:12 »
After seeing Olivier's planes, I tried some of my own, but almost specifically trying to get the planes.

This is 45 minutes worth of 30-second exposures with 100mm focal length.

Peter Connan

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Re: Show us your Star Trails!!!
« Reply #41 on: January 03, 2016, 20:10:15 »
Another stack.