November 25, 2013
One of my favourite pass times as a photographer is shooting landscapes under a night sky. Shooting at night is a time-consuming process but can yield amazing looking images. As with just about all of my photography I want low noise and a good representation of tone so although it’s dark I use a slow ISO. There is no escaping the use of a stable tripod and you will need to invest in a cable release or the electronic equivalent. Oh and get a good torch.
The Set Up
Make sure you have a fully charged camera battery, as long exposures will chew the juice. Set up your camera on the tripod and fit the cable release to the camera. Once you have composed the image set the camera to manual focus and use a bright torch to focus the frame. Choose the aperture to suit the depth of field you want and check that the tripod is properly locked in position so there are no surprises. With the camera on manual, roll the shutter speed dial down to “Bulb”. Bulb keeps the shutter open as long as you are holding the shutter release button down. The cable release does this job for you. With digital cameras a cable release is commonly a digital timer that can be set for a specific exposure in seconds/hours.
To Meter, or Not to Meter?
You need to get your head around the different parameters of working without sunlight. It is possible to over expose a night time shot but it is much more forgiving photography than shooting during the day. There is a surprising amount of light when shooting in a full moon (enough light to read by!) which means full moon exposures may be measured in seconds, but shooting star trails on a dark moon can take hours. In-camera metering doesn’t cope with extreme low light so I have always worked intuitively. Have a go and see what you get. If you have never shot at night, shoot a 1 minute, 5 minute and 15 minute exposures and see how they compare. This will give you a reference point for future shoots. Because you are working in the dark the screen on camera will appear brighter than during the day so use your histogram to reference your exposures. Take note that there will generally be more darker areas in the photo which makes the histogram peak tend to sit further left, toward shadow detail, than a daytime shot.
I approach a full moon shoot in much the same way I treat daytime but the process is much slower. A moonlight exposure will yield highlights and deep shadows the way the sun does. As with full sun I will often use the moon as a backlight and fill in details with torch or controlled flash in specific areas of the frame. When shooting under a bright moon the intensity of the stars will be lessened, as there is more ambient light in the sky.
The moon was quite bright so this exposure was a bit over 4 minutes. I used a torch to fill in the shadow areas on the right of the rock pool.
Painting With Light
Ideally when using a torch to paint with light the end result needs to look even. It will take a bit of practice, as it’s next to impossible to meter accurately. The benefit of this method is that you have complete control of the lighting event. You can backlight, sidelight or make one area bright whilst toning down others.
The torch will probably have a colour cast. If you are lucky you may be able to get a piece of coloured gel that you can tape over it to bring it back to a neutral day light. If not, and you are not happy with the colour, you will need to sort it in post.
The Inverse Square Law
This is a useful bit of physics to remember in principle. Each time you double the distance of the light source away from the subject, the light covers 4 times the area, and is reduced in intensity by 75%. Here it is in practice… If I hold the torch a short distance away from the subject, it creates a very bright light over a small area. As I move further away the light intensity is greatly reduced but covers a much wider area. If you need less light either move the light source further back or move the torch faster. If you need more light you slow it down or come closer. With experience you can better determine the distance and speeds you need to get good light coverage with a torch. It sounds more complicated than it is in practice. Be sure to put an evening or two into experimenting before you set off to shoot your book “Night views of Africa”.
No High-Viz’ please!
You can move around within the frame of a fairly long exposure without showing up in the final image. Wear dark clothes and don’t stay in the same spot for too long. During the exposure the torch should only be switched on when using it to light the image. First, plot the areas you want lit and then work out where you need to be so as not to leave silhouettes in the image. Stand between the camera and the torch and use your hands as a snoot around the torch. Then pointing the torch to where you want the light, turn it on and keep it moving along the subject. If the torchlight is held in one spot it will be hotter than the rest of the pass. You will get a feel for how much light you need in order to get the exposure you want with the torchlight. It pays to do a couple of shorter exposures as a practice run just for the torch part of the exposure. If the composition doesn’t change you may be able to use some parts of those images in your final photo anyway.
A flash happens instantly so it doesn’t offer quite the same level of minute adjustment that a torch does but it in some situations it is a bit easier to control. The inverse square law applies here too. If you can’t get enough grunt out of a single flash to light a big area you can use multiple flashes which will accumulate on a long exposure. If you are using a really deep depth of field and are trying to light a big area you may need to fire it quite a few times. The flash firing twice in this situation doesn’t represent twice as much light. Do some test shots to test your lighting techniques before committing to a long ambient exposure and don’t be afraid to keep firing the flash multiple times to build up to a suitable exposure. From memory 4 flashes for 1 stop 8 for 2 stops etc. Give it a second between full power discharges, as the flash might get hot. Modern flashguns have multiple strobe settings that do this job.
This was a 20 minute exposure which I snuck in just before the clouds rolled in.
Finding Celestial South
We’ve all seen the photos of star trails going around a single axis in the sky. This point happens in both the northern and the southern skies. They are called Celestial North and Celestial South. I am in the southern hemisphere so I will explain finding Celestial South. Find the Southern Cross and draw an imaginary line between the top and bottom stars. Then draw a line between the two pointer stars. Draw a perpendicular line from the middle of the two separate lines you have drawn and where they meet is Celestial South. To get strong star trails, shoot either before or after the moon has set or on the dark moon.
Country skies are much more dynamic as they are away from the influence of city lights but that is no reason not to get out and hone your skills in the backyard or at the local park. If you are camping on site, shoot the location during the day, refine your compositions and plot your lighting. It will make for a more productive night shoot. Night photography has taught me a stack of different skills as well as yielding some cracking images. Oh, and it’s a great excuse to spend some time in the bush at night.
Tags: Andy Rasheed eyefood, approach to photography, Combining Flash with Ambient lightin, FInding celestial south, painting with light, photography tutorials, understanding lighting conditions, www.eyefood.com.au
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