Digital Low Light Photography Explained
By Geoff Harris •
Night Photography and Long Exposure photography
Understanding the basics
My name is Tony Worobiec. I teach a MyPhotoSchool course on Digital Low Light Photography. In this article I will aims to cover the main technical problems you are likely to encounter when photographing in low light or at night.
Many inexperienced photographers think that there are many difficult technical challenges involved with this kind of photography, but as you will quickly discover, photographing at night is no more difficult than during the day.
The first thing to understand is that when photographing at night, you are able to capture the world in an entirely new way. If you are prepared to shoot at this inconvenient time of day, you will be rewarded with mysteriously beautiful images; if you have never done this kind of work before, you might wonder how to focus in the dark- it is much easier than you think.
There will always be some area of light you can focus on and if you are still not sure, then use a small aperture which should ensure every part of your image remains in focus. Finally, if your lens has an auto-focus facility, turn it off. It will have great difficulty seeing a suitable point of focus therefore it goes into “hunt-mode”. What this means is that is cannot focus on anything.
One of the drawbacks of photographing in low light is that you can encounter noise - an increased appearance of graininess which can reduce the overall quality of the image. This can be easily overcome. Most modern DSLR cameras now offer a Noise Reduction facility.
It will be available within the cameras menu and should be selected when making exposures of one second or more. If it proves impractical to use the camera’s Noise Reduction facility, this can be remedied after you have taken your photograph when using the RAW Converter.
Finally, there are several image editing software packages you may wish to use which will solve this problem; the best known is Neat Image, which you can download from www.neatimage.com.
It is sometimes quite difficult seeing the horizon in low light. Some tripods have a spirit level built into the tripod head, but if your does not, then most camera shops now sell small spirit level attachments which you can place on the camera’s hot-shoe. If it’s dark, you might still have problems seeing whether your camera is level, so always have a small torch available.
As most of your photographs will require lengthy exposures, a tripod is an essential piece of equipment. I view my tripod second only in importance to my camera.
With it I know I am able to choose any ISO I want together with whatever aperture I need. If you do not own a tripod, the general advice is to buy the best you can afford and the heaviest you can comfortably carry.
Some might question this last point, but as many of your shots might require exposures of five minutes or more, and if you are photographing landscape, for example, you could quite easily experience strong gusts of wind. Your tripod should be heavy enough to withstand that.
It is also worth giving consideration to the tripod head – as you will need to be able to use it with ease- I would strongly recommend getting a ball and socket type.
This is a typical example where a tripod is essential. To achieve this shot, I needed an exposure time of 142 seconds – that’s nearly two and a half minutes! Clearly hand-holding a camera for that long is out of the question.
This might be an appropriate time to discuss the Bulb setting on your camera. Most cameras have a maximum automated shutter speed of just 30 seconds; all however will also have one called Bulb or B. In order to set the shutter speed for longer than 30 seconds, select Bulb and keep the aperture open for as long as you need by using the cable release.
If your camera does not appear to have a dedicated Bulb setting, you may well find it within the camera’s Manual Mode. If you are unsure, refer to your Camera manual.
One of the aspects of night photography which surprises many inexperienced photographers is how easily night can be made to look like day. While this looks as if it has been taken in normal daylight, the sun had set about 25 minutes earlier and I needed to use an exposure of 7 seconds.
If you are in doubt, look in the bottom left corner and you will see the moving headlights from several cars. I am frequently asked what ISO rating should you use when photographing at night; if you are using a tripod, use the ISO rating you are most comfortable with.
When you are photographing in the daytime, it is very easy to see whether the exposure is accurate; most of us look in the camera’s monitor and we can immediately see if we have been successful.
However, the monitor can appear deceptively bright at night-time which can often lead to under-exposure. It is far better that you check the Histogram instead; All DSLR cameras will offer this facility.
While it is normal in low light for the histogram to bunch slightly to the left, if this is excessive you are in danger of under-exposing.
As I explained earlier, Noise will always pose a problem when photographing at night; one way of over-coming this is to make sure that you do not under-expose.
The other important technical consideration is which White Light balance to use.
Thankfully, unless you are photographing artificially illuminated buildings, this need not be a problem.
In 99% of cases the automated white light facility, often referred to AWB should be accurate.
When photographing at night you have other things to think about, so it does help to have the AWB facility switched on.
It is worth noting that if the white light balance is wrong, this is very easily corrected in the RAW Converter.
Let’s talk about filters. This might strike you as strange, but just occasionally it does help to make a picture taken in daytime look as if it has been captured at night.
Hopefully one thing you will have learnt is that with long exposures, interesting things happen with the sky. In this example, with the available light I should have used a shutter speed of 1/125th second. The result would have been boring.
By using a very dense neutral density filter, the light reaching the sensor was considerably reduced therefore the exposure I needed was increased to 50 seconds. By using this filter I was able to transform day into night!
I‘ve used the same trick here! While it was near sunset, there was still plenty of light in the sky. Without the neutral density filter, my normal shutter speed should have been 1/30th second, but as soon as I put the filter on, this was increased to 66 seconds.
What had fascinated me when I took this shot was the wonderful movement of the cloud set against the snowy mountain. By using this light-reducing filter, I was able to capture this fascinating movement.
What do these filters look like! They are most commonly made as screw-on filters and act like a pair of sunglasses. A neutral density filter is used to reduce the amount of light reaching the sensor by absorbing the same amount of all the wave-lengths, therefore it should not alter the colour in any way. These filters come in different strengths.
A Neutral Density 2 filter allows 50% of the light to reach your sensor, while at the other extreme the 8 filter allows only twelve and half %. When using one of these stronger filters, you will not be able to see through it, so you should focus your picture first, then add the filter. The results can be awesome!
Another filter you may wish to use, particularly when photographing landscape, is a graduated neutral density filter. This filter is similar to the neutral density filters we have just been discussing, except that it is half grey and half clear; b making sure that the darker part filters the lighter part of the scene, exposure balance is restored.
Often, even at night, the sky is much lighter than the foreground. By using a graduated filter, it is possible to balance the exposure of the sky with the foreground and therefore capture detail throughout the picture. These filters can be soft or hard graduated, depending on the task in hand. In this example, I have used a soft filter.
It is possible to buy screw-on graduated filters, but they more commonly part of a modular system. Graduated filters come in different strengths. You can have a “3” - which equates to a one stop reduction in light- a “6” which equates to two stops and finally a “9” which equates to three stops. They are unquestionably very useful filters.
If you would like to learn more about low light, night or long exposure photography why not join me for my Digital Low Light Photography Course
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