The “narrow” in this instance is in reference to the depth of field used in the photograph.  The part of the image that is in focus is a very small (narrow) portion while the rest of the image is blurred out.

First the basics, what is star trail photography?  A star trail photograph is one in which you capture the motion of the stars as the earth rotatesby using long exposure shots.  The trail of light you see in the image is the star at various points in the night sky as time passes and the earth moves.  In my image above I got the start of the concept.  But most star trail photos you see will have significantly more movement, i.e. longer trails, of the stars.  So for next time I have a few pointers.

1) The darker the sky the better.  That means you are going to need to head away from metropolitan areas and the light pollution they emit.  I also shot this three nights before the full moon which resulted in too much moon light to get optimal star trail images.  So drive out into the desert or country away from the city lights and consult a moon calendar before you go to make sure you have it as dark as possible.

2) No exceptions, you are going to need a tripod for this.  Hand holding will never work unless you have the steadiness of a rock for very long exposures.  But why risk it, take your tripod.

3) Focusing can be a bit tricky with photography in environments that are this dark.  If you can focus manually that is good.  Alternatively you can focus on something that is lit enough to see in the distance with auto focus then switch the camera to manual focus and aim the camera in the direction you plan to shoot.  Don’t do your star trail photography in the direction of the light source.  This will lock int he camera set auto focus and maintain it as long as you don’t change the focal length.

4) Camera settings: You will want to experiment here and find what works best for the setting you are in, but in general these are the settings that I found worked for me.

• The lower the ISO the better to prevent noise (100 is best)
• An f/stop in the range of 2.8 – 4.6 worked well for me
• Set white balance to auto

5) Composition: Composition was a bit of an after thought my first time out photographing star trails.  But it shouldn’t be.  This is a matter of personal taste, but I think having something in addition to the night sky in your composition really enhances it.  That could be a building, trees (be careful of windy nights where a tree can blur in a long exposure) or a mountain or hill  the distance.  Make sure you pick something that is going to hold relatively still during your long exposures.

6) For the actual photographs you have two options.  Really long exposures using bulb mode or multiple long exposures.  I tried both and found that the bulb mode exposures did not work well for me.  I was getting too much noise and light interference.  If I had had a darker night that might not have been an issue.  But in this setting I found that the multiple long exposure method worked better. To use this method:

• Set your shutter speed to 30 seconds.
• Set the drive mode (as it is called on my Sony) to continuous.  Might be sports or action mode on some cameras.
• Connect a remote shutter release cable and after you click it once lock it so that it stays held down.  This will allow the camera to continually take 30 second shots one right after the other.
• The number of shots you will need depends on how long you want your star trails to be.  I would recommend at least 5 minutes, which is 10 shots.  But the longer the better.
• DO NOT MOVE THE TRIPOD OR CAMERA.  This will ruin things for the next step.

7) Processing the images.  Once you have 10+ images you are going to need to combine them into one to make the final image.  There is a free star trail software program you can download that does a really good job of stacking your images and giving you a JPEG or TIFF file.

8) A few extras to bring along that can help.

• A flashlight
• A chair, you are going to want to be comfortable while you wait for these long shots.
• Extra charged batteries.  Long exposures like these can really drain your batteries.  Be prepared.
• A guide to the stars.  You might want to know what you are photographing.
• A jacket.  It can get cold out in the middle of nowhere at night.
• A friend.  It can also get lonely and scary out in the middle of no where at night.

So now I think I am ready to head out to the desert again and try my hand at star trail photography once more.  The next new moon is towards the end of the month according to my moon calendar and I am ready with what I learned this first time around.  Check back for attempt number two.

1. Always (always) use a tripod.  The settings necessary for good night time photography do not allow for hand holding the camera.
2. Use a low ISO (400 or less).  This may sound counter-intuitive since a higher ISO is generally used for low light situations. But if you are following tip #1 above you can keep the ISO low and compensate for the low light with aperture and shutter speed thereby keeping noise to a minimum.
3. Set your aperture to f/5.6 – f/8.0.  This is obviously going to depend on your exact lighting conditions but this is a good rule of thumb and starting point.
4. Use l0nger shutter speeds.  With the low ISO and aperture int he f/8.0 neighborhood you can get the proper exposure through keeping the shutter open longer.  Experiment with different shutter speeds to get your ideal exposure.
5. Keep the anti-shake off.  When you camera is on a tripod this feature is not necessary and the camera might actually try to compensate for shake that is not there.
6. Use a cable release.  The less you touch the camera directly the better.  Event he act of pressing the shutter could be enough movement to blur the image.
7. After framing your shot close the eye piece cover to prevent light from getting in.  Since you will not have your eye against the eye piece during these long exposures you want to use another method to keep the light out.  Most cameras have either a cover you can place over the eye piece or a little “door” that closes over it.

Here are two images to give an idea of what you can do with HDR photography versus processing the same image in PhotoShop.

This is the PhotoShop edited photograph.   I did not do much here but I did increase the vibrance and saturation a bit and lightened the image overall.  This is not a bad image in general.  But the sky is very dull and the shadows in the lower left corner are a little dark.

This is the HDR processed version of the image above.  It is a combination of three exposures of the same scene; one exposed normally, one over exposed and one under exposed.  This is the essence of HDR photography in that it allows you to correctly expose for all areas of the scene with different shots and then merge them all together.  This image is not perfect either; the saturation could be toned down a bit and the patio furniture has lost its true color.  But those things are easily corrected and it is more a matter of personal taste.  What is more important is the sky and the dark areas.  I was able to expose for the sky alone in one image and capture the blue hues and the glow of the late afternoon sun.  The shadows on the back wall and around the rocker are also now gone.

Quick Tips for Photographing Fireworks

1) Tripod – It goes without saying (although I am saying it), you MUST use a tripod for decent fireworks photographs.  With the longer shutter speeds required for night photography the steadiness a tripod provides is essential.

2) Aperture – You might think that since it is dark out you want to open you aperture up to f/5.6 or bigger.  Makes sense, but actually I have found that keeping your aperture around f/8 is ideal.  You need to balance the night and the great amount of light that the fireworks give off.  Use your aperture priority setting as well so you can determine the f/stop and the camera can set the shutter speed accordingly.

3) ISO – My Sony Alpha 850 can go up to an ISO of 6400.  For extreme low light situations that might be perfect.  But remember that even in the best cameras the higher the ISO the more noise you are going to get.  Since you are already using a tripod you can set your ISO lower and take advantage of the steadiness of the tripod to use longer shutter speeds rather than higher ISO.  If possible keep your ISO at around 100-200.

4) Focus – It is not easy to focus on the distant horizon and leave it focused while you wait for the fireworks to explode while on auto focus.  One good trick is to let the camera focus while on auto and then while holding that focus switch it to manual so that you basically lock in the focus.

For more great fireworks photography tips here are some additional resources.

Tips for Photographing Fireworks

How to Photograph Fireworks Displays from Digital Photography School

Photograph Fireworks – Wired How-To Wiki