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Star Trails Need Help
Hello All.

In two weeks I will have to take a camping trip. I thought this might be a good time to try my hand at Star Trails. This is something I have never done and don't really know where to start. The equipment I have to use is a Canon XT, 18-55mm kit lens, 75-300mm lens, and the RC1 Remote. I also have a tripod. Could someone please give me a starting point for exposures.

Will this reflect too much light? The area I will be in should be very dark.Thanks in adance for any info.Dale..

Comments (14)

6 HOURS and no replies... Everyone must be out enjoying the day and taking photographs. Here is a one quick result of a google search:http://www.danheller.com/star-trails.html.

Warm regards,DOF..

Comment #1

Great link. I never thought to just google myself for an answer. I guess forums like this are making me lazy.Dale..

Comment #2

I shot some star trails many years ago to good effect..

For me, the most dramatic results were of the North Star, since it "moves" the least in the sky and the other stars leave their trails encircling the North star. Of course, the farther North you are, the easier this is. You have to be in a very dark area for this to work far away (miles, preferably) from the city lights..

Obviously, a tripod is a must. Some digital cameras, even DSLRs, might not let you shoot a bulb exposure of enough duration for a decent shot..

When I did this before using my 35mm film camera, I opened the shutter for several hours. I used a shutter release cable that had a thumb screw clamp. If I recall, I shot using a small aperture to minimize ambient lighting. The stars themselves are bright enough to produce the desired streaking even at a small aperture. Film was ISO 64 Ektachrome, my favorite slide film.

I used a wide lens, allowing me to include some tree foliage in the periphery..

Http://www.pbase.com/digirob..

Comment #3

The link that Dad of Four posted mentioned battery drain for a digital camera. That is an issue that I had not considered. I will not be any where near electircal supplies. Any suggestions as to how to conserve battery power.Dale..

Comment #4

1) Bring extra, charged batteries.

2) Bring an inverter for your car, so you can run your camera battery charger from your car battery..

3) Run a test at your home, before going on your trip. From a fully-charged battery, try a sequence of 1/2 hour exposures, checking the battery meter between exposures..

Don't forget to turn off dark exposure compensation the one that shoots a blank, shutter-closed shot for the same time as the original shot. This will double your battery consumption, as well as taking extra time between long exposures...

Comment #5

Swapping cells is not practical unless you have a dual-cell optional grip (unlikely). The only solution that I can see is to use external power. Since you probably already have a DSLR, I imagine you can find an external power adapter for your body. Some cameras have power jacks, others use a false battery slug that has a lead that connects to the mains..

Very good suggestion to turn off dark frame exposure I didn't even think of that..

'course, last time I did this was in the 70s, lol..

Patrick Murphy wrote:.

1) Bring extra, charged batteries2) Bring an inverter for your car, so you can run your camera batterycharger from your car battery.3) Run a test at your home, before going on your trip. From afully-charged battery, try a sequence of 1/2 hour exposures, checkingthe battery meter between exposures..

Don't forget to turn off dark exposure compensation the one thatshoots a blank, shutter-closed shot for the same time as the originalshot. This will double your battery consumption, as well as takingextra time between long exposures..

Http://www.pbase.com/digirob..

Comment #6

As a newbie I am not sure what the Dark Frame Exposure setting is. On a Rebel XT where in the menu settings will I find it, and what exactlly does it do?ThanksDale..

Comment #7

Good points so far: tripod, AC adapter with inverter to car battery if no manual bulb setting, and turn off noise reduction. Leave the shutter open for hours. If you can, use a prime wide-angle lens (12 to 28 mm) at full open or f/2.8. Shoot away from the moon and use a lens hood to keep and moon shine from the lens. If you have a full moon you can expose about 30 minutes at f/2 to get a "daylight" looking scene with short star trails. I did some in the Grand Canyon like this and they are spooky.Severinson..

Comment #8

Daleofmesa wrote:.

As a newbie I am not sure what the Dark Frame Exposure setting is. Ona Rebel XT where in the menu settings will I find it, and whatexactlly does it do?.

It is in the custom function settings on the XT (p. 148 of the XT manual) under C.Fn-2 Long exposure noise reduction. Set it to 0 (off)..

Basically, Dark Frame Subtraction is when the camera takes the photo, then takes a 2nd photo at the same exposure but with the shutter closed. It then subtracts the 2nd photo (which should in theory be black if there was no noise/hot pixels) from the 1st photo. By doing this, the camera is able to eliminate hot/stuck pixels and some types of noise. Of course, this doubles the exposure time...

Comment #9

Wow that is a ton of help. Thanks!.

I was doing some shorter exposure trails a few days ago and was getting a little irritated with the fact that it took so dang long to process the image afterwards. I knew it was because of the long exposure noise reduction that I had on, but thought it was best. Thanks for the tip..

But do you then use noise reduction software on your computer in processing? Or just leave it?..

Comment #10

NiMH wrote:.

But do you then use noise reduction software on your computer inprocessing? Or just leave it?.

I don't shoot star trails, so I can't really answer that question. However, you will most likely be shooting at low ISO to get the long shutter speed, so hopefully noise should not be much of a problem. Also, clear night skies generally are cold, so that should also help with the noise..

Note, the noise is not the same noise that you normally see in high ISO shots, so I'm not sure how good NR software will work. This Dark Frame Subtraction is more for stuck pixels and thermal signal noise of the sensor..

See link for example:.

Http://www.astropix.com/HTML/J_DIGIT/JPG_DFS.HTM.

Move your mouse over the picture to see the effect, and move your mouse over the text "The Dark Frame" below the picture to see what the dark frame noise looks like...

Comment #11

Hmm, thanks for the response. So dark frame subtraction is the same as Canon's Long Exposure Noise Reduction? I only ask because the brief trails that I shot were from my back deck at 100 ISO for only a few minutes (that's all I could hold the bulb for, waiting on my remote) and they appeared relatively noisy. But I guess that's probably due to my location - it is hardly free of light pollution. I'm hoping to make a quick trip up the Gorge soon with my tripod and shutter release cable to do just this...

Comment #12

If it's just the star trails you want, why do you need to get a 2-hour or more exposure?.

Why not breaking it down to much shorter exposures, then combine them (e.g. with the startrails applicationhttp://www.startrails.de/html/software.html.

Here's a very simple example. It took me 15 mins. 30 exposures, 30 seconds each..

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Http://www.flickr.com/photos/96953368@N00/..

Comment #13

NiMH wrote:.

Wow that is a ton of help. Thanks!.

I was doing some shorter exposure trails a few days ago and wasgetting a little irritated with the fact that it took so dang long toprocess the image afterwards. I knew it was because of the longexposure noise reduction that I had on, but thought it was best..

It is best - it works very well in my experience. But it has one serious shortcoming as you have discovered!..

Comment #14

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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