Photographing Stars and star Trails

13th August 2014
Photographing Stars and Star Trails can be really fun, the result is often unknown and can be very different than what you expected !
To Photograph Stars you will need a good sturdy Tripod, a DSLR camera that has a good ISO range and that can handle noise reasonably well, you will also need a cable release or trigger system, a wide angle lens of at least 35mm is preferable, I will often use a 16-24mm lens or a 24-70mm lens and sometimes even a 16mm lens.

Stars and Dead Tree, photographed in Botswana ISO 3200 at 30 sec exposure.

This is how I go about setting up to photograph the stars, I will find a nice open spot that preferably has a nice strong foreground that will be silhouetted against the night sky, I will often set up the tripod nice and low to include as much sky as possible, once the tripod and camera has been set up I will set the Camera to Manuel mode starting at about F3.5 or F2.8 and a shutter speed of approx. 1 to 5 seconds depending on the ISO, I then push the ISO really high on the Camera to about 12800 or even 25000 this is just so I can take a few test images at a faster shutter speed to see if my composition is correct and that the horizon etc is nice and straight.
Once I am happy that my composition and horizons etc are correct I will now set the focus on the camera, if your foreground subject is close enough I shine a strong light onto the subject and use the Cameras autofocus system to focus on the object, alternatively I will go into live view mode on the camera and zoom in on the viewfinder and manually adjust the focus until it is spot on. If the foreground subject is too far away to focus on then I will set the lens to Manuel focus and turn the focus ring to infinity and then very slightly back, this should be sufficient to ensure the foreground and stars are nice and sharp as your lens is now focused to infinity, I will often then take a few test images at a high ISO to double check my focus before starting.
Once I am happy that my composition, horizon and focus are all correct I will then drop the ISO on the camera between ISO 2000 and 3200, this will depend on how bright the night sky is, I will keep the lens aperture at F3.5 or F2.8 and I will then change the shutter speed to between 15 seconds and 30 seconds, again depending on the ISO and the brightness of the sky, after taking the first shot I will review the image to see if it is too bright or too dark, I will then adjust the ISO and shutter speed to make the changes I want, remember when reviewing your images at night in a dark environment they will always look brighter than what they really are and once downloaded on your computer they always seen a little underexposed, so for this reason I like to shoot my star images so they look almost too bright when seen on the cameras display screen.

Stars and Aloe,photographed in Schoemanskloof South Africa ISO 2500 at 30 sec exposure.

To Shoot Star trails I will follow the above procedure except that I will point my camera towards the Southern Cross, this is how you get circular star trails, if you point your camera in any other direction you will get straight or slightly curved star trails, I will now change from Manuel mode to Bulb mode and I will drop my ISO down to between 200 and 400, again depending on the brightness of the sky.

Star trail and Aloe, photographed in Schoemanskloof South Africa ISO 400 at 20 minute exposure.

I will now use the cable release, push down and lock the cable release so the shutter of the camera remains open, depending on how much of a star trail you want will depend on how long the shutter remains open, I have found that if left open for about 20 minutes I will get a great result and the star trail will be circular, experiment and see what you like.
Another way of making a star trail Image is to take about 90 minutes worth of 30 second exposures of the night sky and then to blend all or some of the images together in Photoshop or a program called Starstax, a fun way to make star trails in the computer and not in the camera.

Star trail over Earth Lodge, 145 x 30 second exposure images layered in StarStax at ISO 2500.

Also remember to switch off or disable the long exposure noise reduction in your camera, otherwise your camera ends up processing the image for as long as the shutter was open, trust me that waiting 20 minutes to review a image after the shutter has closed because the camera is doing its noise reduction is very frustrating !

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