We have all seen those amazing pictures of waterfalls where the water looks soft and fluffy or pictures of the stars at night and maybe you have wondered how it is done and if it is possible to do this type of long exposure with a phone camera.
Long Exposure Photography
You will be pleased to know that yes, it is possible to create long exposure pictures with a smartphone camera. Here is a list of the settings we need to control in order to take great long exposures with our smartphone camera.
Let’s look at each of these, in turn, to learn how to set up our smartphone cameras for long exposures.
As the name suggestes, we need to set a long exposure this means setting the shutter speed of our smartphone camera to more than a second, depending on the type of long exposure we are taking.
A one second or longer exposure introduces a big problem, we cannot hand hold the camera and take a picture at that long of shutter speed. our pictures will turn out blurry if we do due to camera shake. We need to use a tripod. A tripod will enable us to take longer exposures without causing camera shake.
Tripods come in many shapes and sizes and the style of tripod we need depends on what kind of tripod we need. I will discuss tripods later in the article. For now, just keep a mental note that this is something that we will need for long exposure pictures.
The vast majority of smartphone cameras have fixed aperture. The aperture determines how much light comes through the lens and hits the smartphone image sensor. As we cannot change the aperture in our smartphone camera we will need to find another way to control the amount of light coming through the lens.
If we have a one second shutter speed on a bright sunny day, the picture will be hugely over exposed as the aperture cannot be changed to reduce the amount of light, in this case we would need to use ND (natural density) filters.
ND filters allow us to reduce the amount of light coming through the lens which we will need to do when taking long exposures during the day.
ISO relates to the sensitivity of the image sensor, a low ISO means the sensor is at it least sensitive and gives clear sharp images, increasing the ISO gives the image sensor more sensitivity for low light situations but this introduces noise (grain) into our images.
While focus does not directly impact the exposure it is still something that we need to consider when taking long exposures. We need to make sure that the area we want to feature is in focus. During the day this is not so much of a problem, but at night it can be difficult to see what is actually in focus.
Long Exposures During The Day
There are two different categories of long exposure, during the daytime and at night and each of these have different considerations that we need to be aware of.
When taking long exposures during the day, we will need a tripod and a set of ND filters. The ND filters enable us to control how much light comes through the lens and enable us to get correct exposure will a long shutter speed.
Long exposures of the sea or running water are particularly effective. Long exposure of the see can flatten the waves and give the sea a spectacularly flat look. This can be contrasted against rocks or other features. to achieve this we would need to use a very long exposure of twenty-five or thirty seconds with an ND filter of ND512 or a nine-stop ND filter.
Waterfalls also take on a magical look when captured with long exposures. Capturing waterfalls is more flexible as the water tends to move faster than the sea. we can use a shorter shutter speed of five seconds with an ND128 a seven-stop ND filter depending on the light conditions.
What Are ND Filters?
ND or Neutral Density filters are used in stills photography and film making to control how much light gets through the lens. This is important in photography because typically smartphones use very high shutter speeds in daylight, this is typically due to the faster lenses in modern smartphone cameras and the way smartphone cameras are designed to get the sharpest images possible with a small camera. So if we take a long exposure during the day it will be overexposed without using ND filters to slow down the shutter speed.
To get a cinematic look while shooting video we want to make sure that the shutter speed is twice that of the frames per second rate. So at thirty frames per second, we are looking for a shutter speed of 1/60th of a second, this is almost impossible in bright sunshine. This combination of shutter speed and framerate provides a very natural look where there is slight motion blur in faster movement. This setting matches how the human eye sees things naturally.
In photography, ND filters are also used to slow down the shutter speed, but this is used to create longer exposures during daylight. Longer exposures can enable us to smooth out flowing water or to blur moving objects while stationary objects remain sharp.
How Do ND Filters Work?
ND filters are made from darkened glass or plastic and are placed in front of the camera lens to reduce the amount of light, rather like sunglasses for our eyes.
There are several different grades or ND filters. A grade refers to how much light the ND filter allows through, typically this is measured like lens aperture in f/stops. So a five-stop ND filter will be equivalent to stopping down the aperture of your lens by five stops. This is exponential as each stop halves the amount of light of the previous stop.
When filming video, we need to an exact ND filter that will allow the exposure to be twice the number of frames (framerate). It will be necessary to have a variety of ND filters to cater for different lighting conditions. You will need a higher stop ND filter for bright sunny days and a lower stop filter for duller days.
In photography, the ND filter range is not as strict as in film and you don’t have to worry about framerate. However, you will need to consider the kind of effect you are looking for. If you want to soften the look of a waterfall with a twenty-second exposure, you will need to find a suitable strength ND filter that will provide the correct level of ISO and aperture that you are looking for. I have another article that explains how aperture affects depth of field if you want to check it out.
Typically when using ND filters for long exposure we will need to use a tripod, as the shutter speed will be way too low for handheld shots. A shutter speed below 1/60 is likely to result in camera shake unless we use a tripod or the smartphone camera has optical image stabilization.
What Are The Most Common ND Filters?
There are five ND filters that are most commonly used with smartphones, these are:
The ND32 is equivalent to a five-stop reduction in light, reducing the shutter from 1/250 of a second to 1/8 of a second.
The ND64 is equivalent to a six-stop reduction in light, reducing the shutter from 1/250 of a second to 1/4 of a second.
The ND128 is equivalent to a seven-stop reduction, reducing the shutter speed from 1/250 of a second to 1/2 of a second.
The ND256 is equivalent to an eight-stop reduction, reducing the shutter speed from 1/250 of a second to 1 second.
The ND512 is equivalent to a nine-stop reduction, reducing the shutter speed from 1/250 of a second to 2 seconds.
One of the great benefits of using an ND filter is that it enables you to keep the ISO at a low setting, and this results in better quality videos and photographs while still working in bright conditions. These three ND filters offer a wide range of flexibility when shooting video or photographs.
Different Options for ND Filters
As you know every smartphone manufacturer has a slightly different design for their smartphone camera. As a result, there are no standards when it comes to ND filters for smartphone cameras.
Like everything else, there are different options when it comes to the quality of an ND filter. Some ND filters are made of plastic, while higher-end Pro ND filters are made from high-quality glass.
We have to carefully consider what we want to put in front of our camera lens. Some lower-end ND filters can have a color cast that needs to be fixed in post-production. This should not happen in good quality Pro ND filters, we should get natural looking footage and photographs without any color tint.
One of the biggest names to look out for is Polar Pro, this company started out making Pro quality ND filters for drones, but they now also have options for smartphone cameras.
Due to the lack of a common standard, some ND filters are designed to be clipped onto the camera. While others are designed screwed onto extension lenses like a wide angle or telephoto extension. Some of the more recent cheaper ND filters are variable, from what I have researched, many of the variable filters are not as good as the fixed stop ND filters, so they are a bit of a gamble. This technology is quite new so there is a good chance that in the next few years variable ND filters will improve. For now, I would stick with Pro quality ND filters to match your requirements.
Long Exposures At Night
One of my favourite kinds of photography, long exposures taken at night can produce some very dramatic pictures. We are still gong to need a tripod but we won’t need ND filters at night. We need to get as much light as possible through our smartphone camera lens in order to get the pictures we want.
I really enjoy taking pictures of the stars at night, but it’s not easy to get a good astrophotography picture with a smartphone camera. We need to be in a location where there is minimal light pollution. It also has to be a clear night with no clouds.
Focusing At Night
You smartphone camera will not be able to auto-focus at night, so it will be necessary to use manual focus. This can cause us an issue at night, as we often cannot see much when looking through the smartphone screen. The easiest way to deal with this is to consider where we will want to focus while it is still light and then memorize where the manual focus setting is on the camera.
If you are trying to capture stars it’s not so much of a problem, as smartphone cameras usually have focus indicators for infinity, which makes things a lot easier.
Another way to deal with this is to use a torch to get the focus point if the subject is not too far away. Manual focus will ensure that the focus point is not changed when the torch is extinguished.
We can either capture trailing stars or static stars. When setting up to capture static stars we want a long exposure but not too long that the stars move due to the Earths natural rotation. The maximum we can get away with before we see a slight trail is about twenty-eight seconds.
We will need to increase the ISO to a setting that does not cause too much noise, also some noise is almost inevitable due to the small size of smartphone camera sensors. Let’s try ISO 800 and a twenty-eight-second exposure as a benchmark. It’s then just a question of tweaking to get the picture we want.
We can do a lot of work in post-production to improve the look of our long exposure pictures. One technique that is often used is picture stacking. We take ten shots of exactly the same picture and then we use some clever software to combine (stack) the ten images into one. Picture stacking software is very clever and can stack images of stars even if the stars have moved between one picture and the next. I use AstroArt for stacking my astrophotography pictures.
It is important to take long exposure pictures in the RAW image format, this provides much better post-processing options than it is possible to get from a JPEG image. Check the smartphone camera settings, the camera may need to be in pro or manual mode to see the RAW image settings.
Trailing stars require a much longer exposure, minutes or even hours. We can reduce the ISO back down to a lower setting as the shutter will be open for a very long time. It’s unlikely that the majority of smartphone cameras will be able to provide an exposure of this length, so it is necessary to download a third-party app.
Long Exposure Camera 2 is a free app that will enable up to five minute exposures, it also allows you to upgrade to the paid version and get Bulb.
Ideally, we want an app that can handle Bulb exposures. These are exposures that enable the shutter to be open for as long as you want. from what I have found most of the apps that support Bulb are paid apps. I’ll leave this with you to decide if this is the kind of photography that you want to pursue.
In this article we have had a brief glimpse into long exposure photography with a smartphone. Long exposures are quite an advanced topic but well worth putting in some effort as the results can be very rewarding.
We have looked at the different setting that needs to be adjusted to achieve a long exposure and the different kinds on long exposure including day and nighttime photography. Finally, we looked at various aspects of astrophotography.
I hope you have enjoyed this brief introduction to long exposures, I’ll see you in the next article.