Long Exposure Photography in 5 steps
The long exposure is probably one of the most popular photo techniques for nature photographers.
And this can be explained very well!
The long exposure is one of those techniques that can bring another dimension to a photo and catch the eye.
An ordinary landscape can take on a completely different look when photographed in a long exposure.
In this article, I suggest you to discover 5 essential steps to start well in long exposure.
We will see which subjects lend themselves to long exposure, how to extend the exposure time and what are the important points to take into account to make your photos successful.
1.Finding the “right” subject
Even before you start setting up your camera, the first step is to find a subject that is suitable for long exposures.
It may seem obvious, but it’s always good to remember it!
The best subjects are those with movement: water from a waterfall, river or the sea, clouds in the sky, car headlights at night, etc.
The best subjects are those with movement.
Why choose a subject with movement? Simply because the sensor will record its movement and produce that special rendering that characterizes the long exposure.
An exposure time of 6 seconds allowed me to record the coming and going of the waves.
2. Taking care of the composition
The long pose can give a magical touch to an ordinary scene, but that’s no reason to botch your work! Particular care must be taken in the composition.
This remains true for any photo, regardless of the technique used.
Once the subject has been identified, don’t set up your equipment in the first place.
Move around and explore the environment in search of the best angle.
If necessary, take a few shots to get a first glimpse of your composition.
By integrating these rocks in the foreground, I have structured the image and added depth.
Exposure time: 8 s
When photographing a landscape, keep in mind the principles of composition that usually make these photos successful.
Include a foreground to add depth, use the guidelines to guide the viewer’s eye, arrange the different elements in the frame in a balanced way, etc.
3- Extend the exposure time
As the name implies, a long exposure consists of exposing the camera sensor for a longer period of time than for a “conventional” shot.
To achieve this, you have to play with the exposure time.
To obtain a longer exposure time, the photographer has several strings to his bow.
The first is to use a small aperture, that is to say to “close” the diaphragm located in the lens to let less light through.
As less light reaches the sensor, the camera will compensate by using a longer exposure time.
But (because there is a “but”) this method is not miraculous.
It doesn’t work all the time.
It is only possible when the brightness is not too high.
Closing the diaphragm in the middle of the day won’t do much good: the exposure time will always be too short.
Unless the sky is very overcast, this method will only work at the beginning or end of the day when the light is already too dim.
An ND64 filter allows you to use an exposure time 64 times longer.
Therefore, there are accessories available to get around this limit.
If you want more leeway and less dependence on external conditions, simply position an optical filter in front of your lens.
ND filters are commonly used: they block some of the light entering the lens, resulting in longer exposure time.
The most opaque ND filters allow very long exposure times: several tens of seconds, even in daylight!
4- Stabilizing the camera
With a long time to pose a new difficulty arises.
When photographing freehand, you will not only record the movement of the subject, you will also record your movements.
This is called camera shake blur and it results in the appearance of blur throughout the image.
Unless you want to achieve a particular effect, this is usually not what you want to achieve…
A 10-second freehand pose.
Motion blur was inevitable!
Stabilizing the camera is therefore an essential prerequisite before starting to photograph in long exposures.
For this, the must consists in using a tripod.
The latter offers great versatility because it allows you to position your camera just about anywhere.
If you are not equipped, you can also simply place your camera on a stable surface: a rock, a low wall, a railing? You will have less latitude in terms of composition, but you can still photograph in long exposure.
That’s the most important thing!
Secondly, it is often necessary to limit the vibrations generated by the pressure of the finger on the shutter release.
Several types of remote controls are available on the market: some are connected directly to the camera with a cable, others are wireless.
Otherwise, the camera’s self-timer will do the trick.
The time elapsed between the pressure of the finger and the release of the photo allows the vibrations to dampen themselves.
5- Controlling exposure
When trying to do a long exposure, it is not always easy to determine the right exposure.
If the exposure time is too short, the image will be underexposed or the effect will not be strong enough.
If the exposure time is too long, there is a risk that the image will be overexposed or the highlights will be burned out.
You should be especially careful about overexposure if you are photographing a bright feature such as a waterfall or the sky.
With long exposures, you must be able to control the exposure perfectly.
To illustrate my point, I suggest you look at an example with the two pictures below.
Exposure time of 4 s
On this first picture, the exposure is correct.
The image is neither too bright nor too dark, and landscape details are preserved.
Now let’s look at the same landscape photographed with a much longer exposure time.
Exposure time of 20 s
With an exposure time of 20 s, the sensor received too much light.
The image is overexposed, and some landscape detail is lost.
To adjust the exposure, you can choose between different exposure modes.
Semi-automatic modes are very useful as the camera assists you in determining the correct exposure.
For example, with shutter speed priority mode (S or Tv depending on the manufacturer), you choose the shutter speed and the camera adjusts the aperture.
Even if it is a semi-automatic mode, this does not protect you from an exposure problem.
Indeed, if you choose too slow a shutter speed, the smallest aperture available on your lens will not be able to compensate for this influx of light.
Conversely, if you choose too fast a speed, the larger aperture on your lens will not be able to provide enough light to the sensor.
To find out if you have exceeded the limit, watch the aperture value in the viewfinder or on the camera screen.
If the aperture value is blinking, it means that your picture will be overexposed or underexposed.
You will need to increase or decrease the shutter speed respectively.
With Aperture Priority Mode (A or Av), the photographer selects the aperture and the camera adjusts the shutter speed.
With this mode, there is less chance of encountering an exposure problem.
The range of shutter speeds available on a camera (usually 1/4000 s to 30 s) can prevent overexposure or underexposure in most cases.
If you have a little more experience, you can also use the manual mode.
With this mode, you choose the aperture and shutter speed yourself.
This mode offers more freedom but is also more dangerous to use.
If you are a beginner, I recommend you to use the aperture priority mode instead.
It’s easier to use and there are fewer exposure surprises!
Finally, as far as ISO sensitivity setting is concerned, I advise you to select a low value: ISO 100 or 200, for example.
Since you want to work with slower speeds, there is no reason to make the sensor more sensitive to light than it is natively.
If the ISO auto mode is on, remember to turn it off before taking a long exposure.
In conclusion, I draw your attention to the fact that long exposure is anything but an exact science.
The movement of the subject but also the luminosity are very variable.
A setting that is valid in one situation will not necessarily be transposable to a situation that seems similar.
Don’t worry if you don’t get the right result the first time.
This is perfectly normal! Try several times and adjust according to what you want to achieve.
I hope this article has made you want to practice the long pose or go deeper into the subject.
If you want to have ideas of subjects to photograph, I recommend you to read my article: “The long exposure: 10 essential subjects”.
The long exposure: 10 essential subjects
When you begin to master the basics of the open/speed couple, the need to discover new techniques is quickly felt.
This is the moment that many photographers choose to learn about long exposures.
By leaving the sensor exposed to light for several seconds (or even minutes), you open the door to new photographic opportunities.
For example, this technique is widely used to capture the movement of a subject.
Whether you’re new to long exposures or are in the process of perfecting your technique, here are 10 topics you should be interested in.
Waterfalls are among the most photographed subjects in long exposure.
And for good reason, by recording the movement of the water, it is possible to make superb yarns.
Even the smallest of waterfalls will immediately take on another dimension.
Exposure time: 10 s
But don’t forget the composition: a long pose is not enough to make a beautiful photo.
After having photographed this waterfall from different angles, I finally decided to keep this photo.
The small waterfall in the foreground brings balance to the composition, the two waterfalls “answering” each other.
The fairground is an ideal place for long poses: numerous rides, colourful lights, etc.
The Ferris wheel, the carousel or any other merry-go-round with a rotation are all ready-made subjects.
The repetition of the movement of the merry-go-rounds gives you all the time you need to experiment and find the right pose time.
The other advantage of the carnival is that you can photograph both day and night.
Exposure time: 8 s
You may already have a night sky with luminous trails without knowing how they were made.
Well, again, the technique used is the long exposure technique.
The sensor registers the movement of the stars in the sky, making it possible to make beautiful star streaks.
In fact, even if the impression is misleading, it is we who are moving (the earth is spinning) and not the stars!
If you want to get pretty concentric circles, you have to look for the North Star and include it in the frame.
It is indeed the only star that does not “move”.
A variation on this is to find an angle that allows you to make a shower of stars falling on the landscape you are photographing.
There are two methods of making a star shower.
You can make a single pose or you can take several poses that you then assemble on your computer.
It would take too long to go into detail here about the advantages and disadvantages of each method, but be aware that both methods exist.
4. Road traffic
Car headlights are a great classic in long exposure photography.
You know those photos where very graphic yellow and red lines wander through the frame.
Photographing in an urban environment generally gives good results, as it adds scenery and therefore strengthens the composition.
Try to position yourself in the axis of the road so that you have both the front and rear lights of the cars.
For this photo, taken in Brisbane, Australia, I was sitting on a footbridge above the road.
This strategic position allowed me to give depth to my image – the lines formed by the headlights going from the foreground to the background.
For the anecdote, this photo was taken without a tripod despite an exposure time of 8 seconds.
I simply used the edge of the railing to put my camera down and then I activated the self-timer to avoid blurred movement when the shutter was released.
Exposure time: 8 s
Rivers are widespread and easy to access and this is surely why many photographers learn the long exposure with this subject.
You don’t need a beautiful mountain stream to get started – I’m sure there’s a river nearby that’s just waiting to be photographed!
To make a striking composition, stand on a rock in the middle of the river (while respecting basic safety rules, of course!).
If the flow is not too strong and the depth is reasonable, you can also get into the water with your tripod.
The spectator will be immersed in the heart of the scene and will have the impression of really being there.
Exposure time: 4 s
As with car headlights, fireworks photography is based on the recording of light trails.
With an additional difficulty though: unless you are in charge of the fireworks show yourself, you don’t know in advance what the exact sequence of the show is.
The success of this type of photo is therefore based on good preparation.
Find out beforehand exactly where the fireworks will be fired, do some scouting to find the best vantage point.
You can focus on a particular bouquet or blaze by keeping the shutter open for a few seconds.
If you want an overall picture, leave the shutter open for several minutes to capture a splendid mix of colours.
The seaside is an invitation to meditation and a source of inspiration for many photographers.
And what better than a long pose to enhance a beautiful seascape! By capturing the comings and goings of the waves, you will give a dreamlike vision of the landscape you have in front of you.
To obtain an interesting result, use an exposure time of several seconds.
The longer the exposure time, the better the effect you will get on the water surface.
However, you must dose your effect precisely and keep enough detail in the bright areas (beware of overexposure!).
Remember to include a foreground when composing your image.
This is not what you will miss on the seaside: pebbles, rocks, pontoons, tree trunks are all elements that you can take advantage of.
Exposure time: 4 s
8. The clouds
As clouds move across the sky, they naturally represent subjects suitable for long exposure shooting.
In broad daylight, unless you have special lighting conditions, you will need to use a photo filter to reduce the amount of light entering the camera.
If you don’t have any accessories, you’ll photograph at nightfall instead.
This will give you enough exposure time to reflect the movement of the clouds and take advantage of the little light left over to ensure the ground is well lit.
Also, try to position yourself in the direction the clouds are moving to make your pictures even more dynamic.
If you are a fan of spectacular photos, the thunderstorm photo is for you! However, capturing a flash in the sky is not necessarily easy at first glance: a minimum of knowledge and practice is necessary to achieve your goal.
Some photographers have specialized in this discipline: they are called storm chasers.
If you are interested in thunderstorm photography, I advise you to visit the site chasseurs-orages.com which is full of useful information to learn about this discipline.
10. The light painting
Light painting (painting with light, in French) is a technique that has been on the rise lately.
For this type of photo, you don’t choose a subject, but on the contrary, you draw it.
All you have to do is place yourself in a dark environment and then draw by moving a light source (flashlight, candle, lighter, etc.) while the shutter remains open.
A variation is to move the camera in front of a light source.
This technique produces excellent results with coloured lights such as Christmas decorations or the multicoloured lights of fairground attractions.
How to get started in long exposure photography?
There is no single definition that characterizes the long exposure in photography.
I would tend to say that the long exposure is synonymous with a sensor exposure time of more than one second.
It’s not just about compensating for low light.
It has an infinitely wider range of applications.
Infinitely more artistic.
Everybody has seen and admired images of waterfalls with beautiful waterfalls or pictures of flowing water.
But do you know all the technical and material components behind these shots?
Why doing a long exposure ?
To put it simply, long exposure is useful or desired in 3 cases:
When the light becomes insufficient and we need to increase our exposure time.
In this case, it is a technical reason.
When we want to blur a movement (example: spun water on a waterfall).
The long pose becomes here an artistic approach.
To remove moving elements from an image (example: to remove tourists from a busy alleyway in front of an urban monument).
The third reason is purely practical.
It is important to remember that the effect produced by a long exposure shot cannot be reproduced in software post-processing.
Best subjects for long exposure photography ?
The thread of waterfalls, the down of the waves or the long trails of clouds in the sky are classic subjects of long exposure in photography.
However, there are many other interesting subjects that deserve your attention.
Here is a small selection, not exhaustive.
Night subjects: the Milky Way, circumpolar photography, fireworks, lightpainting and sparks or even car headlights in the rural or urban landscape.
Daytime subjects: flash portrait in the second curtain, merry-go-rounds and of course passers-by.
In short, anything that moves moderately in a fixed frame.
It’s up to you, through testing and iteration, to achieve the desired effect.
How to make a long exposure in the middle of the day ?
If you’ve ever tried to do a long daytime pose, you’ll tell me that it’s impossible.
Even if you set the ISO to minimum (100 for example) and close your aperture to maximum (f/22 or f/32 in this case), your image will always be overexposed!
The universal solution is to shoot at the end or beginning of the day when the light is very low.
There is another more practical solution to reduce the amount of light entering your lens.
The accessory that will perform this function perfectly is the ND filter.
What is an ND filter ?
An ND filter or “Neutral Density” (Neutral Density) is a surface, made of plastic or glass, more or less opaque, that you screw on (circular filter) or put in front of your lens.
An ND filter only reduces the amount of light.
If it is of good quality, it should not change the final colorimetry of your pictures.
There are 3 types of ND filters:
- the graded ND filter, mostly used in landscape photography to reduce the brightness of the sky.
- the plain ND filter which has a unique light attenuation value
- the variable ND filter, which has the particularity of reducing the light on several values
ND filters can be circular or square.
Circular filters are screwed directly onto the front of your photo lens.
Square filters require another special accessory: the filter holder.
The filter holder attaches to your lens.
The use of a square ND filter is useful if :
- your lens does not have a thread
- you want to use degraded filters
- you want to mix the filters (gradient and plain)
Although it may seem obvious, there is no variable ND filter in square format.
How are ND filters characterized?
The power or at least the light attenuation factor is often represented by multiples of 2.
ND2, ND4, ND8, ND64, ND400 up to ND 1000 are available.
For example, an ND2 corresponds to a filter that divides the amount of light passing through it by 2.
By deduction, if the filter reduces the light passing through the lens, it increases the exposure time proportionally.
Note that ND filters can be accumulated.
This results in much higher light reduction powers and therefore very long exposures.
Illustration of the light attenuation factor of ND filters
Illustration of the light attenuation factor of ND filters
If you want to learn more about ND filters, here’s a video tutorial dedicated to the use of photo filters.
SUMMARY OF REQUIRED EQUIPMENT
The equipment of an amateur long-exposure photographer must meet specific requirements:
- a camera that allows exposure times of more than 30 seconds
- a stable tripod that absorbs all vibrations and avoids blurred movement
- a remote control or interval meter that allows you to comfortably adjust the exposure time and shooting frequency without touching the body directly
ND filters to significantly attenuate the amount of light received by the sensor
Buying a quality ND filter is a budget, whether it is circular or square.
Some filters easily exceed 100 or 200 euros.
Manufacturers such as Cokin or Nisi, have designed more reasonably priced kits with a set of 3 or 6 filters.
Best Settings for long Exposure
Generally speaking, the device is set to the following basic configuration:
- Aperture priority or manual mode (I recommend the manual mode).
- 100 iso (best possible quality)
- Aperture between f/8 and f/14
Banish all sources of vibrations that could alter the sharpness of your entire image.
Therefore, be careful to use a remote control or interval meter (in the worst case, use the self-timer of the camera).
Also avoid positioning your tripod on a surface that generates vibrations (example: wooden bridge crossed by passers-by).
And finally, do not expose your installation to the wind.
For the same obvious reasons, pay attention to the flapping of your camera strap.
The viewfinder of an SLR may let light in during the shooting for several seconds or even tens of seconds.
Do not hesitate to block your eyepiece to guarantee the quality of your image.
Good to know: after a long exposure, your camera will remain unavailable for some time.
Count approximately 1 to 2 times the exposure time you have just made.
For a 1-minute shot, your camera can process the shot for another 1 to 2 minutes.
Setting without an ND filter
As mentioned above, long exposure in the middle of the day, without a dedicated photo accessory, is impossible to achieve.
Long exposure without an ND filter is therefore preferable in very low light conditions.
Do not hesitate to activate the liveview to assist you in focusing in this dark situation.
If your exposure time is less than 30 seconds, you don’t have to switch to Bulb mode.
The cell of your photographic equipment calculates the exposure time needed to shoot your long exposure.
If you exceed 30 seconds, bulb mode allows you to continue shooting for as long as you keep your finger pressed on the shutter release button.
With ND Filter
Adding this accessory to reduce the amount of light received by the sensor requires recalculating the ideal exposure time.
The first step is to record the exposure settings for normal shooting.
I also advise you to focus and frame your image at this stage.
Make a test image to make sure that the focus and exposure metering is correct.
In the second step, you will calculate a new exposure time in accordance with the light attenuation power of the filter.
Here is a concrete example.
For normal shooting, your camera settings indicate an exposure time of 1/100s.
If you attach an ND 1000 filter (corresponding to 10 stops or 10 f-stops) to your lens, you will need 10 seconds of exposure time! (1/100X1000 or 0.01 x 1000=10)
If you’re like me, you don’t like taking your smartphone out all the time to calculate a new exposure time based on the power of the ND filter.
I advise you to always keep a reminder with you.
Of course there will always be situations that won’t fit into the boxes, but in 98% of the cases, you’ll save precious time.
On the internet there are mobile aids or applications, such as the Nisi brand application, which is just perfect.
Post processing for long exposure photography
3 characteristics related to this photographic discipline should catch your attention:
white balance: this should not happen but it may be that the colorimetry of your image is shooting at magenta.
long or very long laying can generate noise: this is why we recommend a configuration at 100 iso
the large closure of the diaphragm may cause spots to appear on the sensor.
Think of removing these defects and automate this treatment on your other shots.
These “flecks” will always be in the same place on the image 😀
Find your own style in long exposure photography
Not everyone likes long exposure, when it is not mandatory or dictated by a specific subject (astrophotography, fireworks).
For all other occasions the long pose is a personal artistic approach.
As we have seen previously, there are practical ways to calculate the ideal exposure time for your long exposure.
But what determines the amount of yarn on a waterfall, apart from yourself? Beyond the technical considerations, you have to make this practice your own artistically.
This way, your image will look like no other!
What is a long exposure photo?
Before going into technical details, it is important to understand our subject.
A long exposure photo can be defined by an image obtained with a sufficiently long exposure time (or shutter speed).
But what kind of exposure time are we talking about? 1 second? 2 seconds? 30 seconds? 20 minutes? Well all these answers are correct.
Pragmatically speaking, we often talk about long exposure photography when, in the same photo, some elements photographed are sharp and others are blurred.
For example, if you take a long shot at night in the middle of the city, you will have the (still) buildings in focus and the headlights of (moving) cars tracing threads of light.
However, it is quite possible to photograph a still life in a long exposure and the result will be an image in which all elements are completely still.
Why use the long exposure technique?
This is an interesting question to ask oneself.
Why use a long exposure to capture a scene when it is very possible to expose the scene in a different way? The answer here depends on the time of the day when you are going to do your long exposure.
The long exposure at night: due to lack of light
At night or in a dark situation, you have three possibilities to properly expose your image: use a relatively long exposure time, use a very large aperture (with a bright lens such as a 50mm f/1.4) or increase the ISO sensitivity.
The use of long laying in these conditions will allow you to :
- maintain a low ISO sensitivity to reduce the appearance of digital noise on your image
- use a small aperture (e.g. f/11 to f/16) to obtain a sufficiently large depth of field and thus have different planes of your image sharp.
On the other hand, a slower shutter speed means that your sensor will be exposed to the scene you’re shooting for a longer period of time, capturing the movement of what you’re shooting and “stacking” it on top of each other.
This technique allows you to obtain artistic renderings such as light spinning, light painting, etc.
Long daytime pose: for an artistic rendering
In daylight, you usually have enough light to photograph a scene at the correct speed without having to use too high an ISO sensitivity or a very large aperture, unless you want a photograph with a very shallow depth of field.
Even so, long daytime exposure can reveal, just like macro photography, a world and a universe completely different from what we are used to seeing.
For example, these photos we took in the middle of the day in the center of Paris.
At the extreme, if you use an extremely long exposure time (several minutes), it is possible to remove any moving subject from the picture.
This is the case of the first photo of a human being taken by Louis Daguerre in 1838.
At the time, the photographic technique required such a long exposure time that only one man is in focus in the photo: he is having his shoes shined in the streets of Paris.
Louis Daguerre – 1838 – on this photo taken in the middle of the day, we see no movement in the street because the exposure time was very long.
We can however see on the lower left the silhouette of a man having his shoes shined.
But how can we not end up with a completely white image with such a slow shutter speed? This is where an important accessory, the ND filter, comes into play, which we talk about in the next section.
The equipment needed to make a long exposure picture
To photograph in long exposure, you need very few things.
The most important thing is to have a camera with manual settings that allows you to use exposure times of several seconds (usually up to 30 seconds).
It’s even better if you have a camera with B and T exposure settings.
In B exposure, the shutter is open as long as you keep your finger on the shutter release button, while in T exposure, the shutter opens when the shutter release button is pressed for the first time and does not close again until the shutter release button is pressed again.
A tripod to stabilize your image
Because long exposures involve very slow shutter speeds, if you don’t stabilize your camera you’re bound to get blurry pictures.
If it is possible to mount the camera on a curb or wall, it is better to have a tripod to perfectly adjust the framing.
We have recently published an article to help you choose a travel tripod, the tips here are also useful to help you with any tripod purchase.
Preferably, choose a model that is well-made, stable and allows for precise adjustments (a good head is important).
A remote control or self-timer
While the tripod helps stabilize your camera, pressing the shutter release button will cause vibrations that are detrimental to the sharpness of your picture.
It is therefore advisable to choose a remote shutter release, using a wired or wireless remote control.
Some modern cameras have a WiFi connection that allows you to trigger from a smartphone: don’t be satisfied with this, as it may reduce your battery life (smartphone and camera).
It’s better to prefer a simple shutter release.
If you don’t have one, you can also use the self-timer built into the camera so that the camera doesn’t vibrate when you shoot.
An extra battery
Long exposures tend to consume a lot more energy than a conventional photo, so to avoid running dry, charge your battery well before you go.
We even advise you to use an extra backup battery, you can never be too careful.
A neutral density filter
For long exposures in daylight, you will need to use a neutral density filter (ND filter) in front of your lens.
The Neutral Density Filter is a photo filter that darkens the image without changing the hue or color rendering.
This gives the photographer more flexibility, for example, by allowing them to choose a larger aperture (and therefore a shallower depth of field) or a longer exposure time (with motion blur as appropriate).
There are different types of filters, circular and rectangular, variable or not.
We have tested the NiSi filter holder system which seduced us by its quality and scalability, but other brands such as LEE Filters, Cokin, Format Hittech are also very good.
Nisi filter holder
There are ND filters with different optical densities (indicated in x ND).
The higher the density, the darker the filter will be and the less light will pass through, which we will see later in this article.
For very long exposure times (more than 30 seconds), B mode or T mode should be used.
With these modes, you must count the exposure time yourself and then release the shutter release button or press it again to stop the exposure of your picture.
A simple stopwatch, watch or similar application on your smartphone will be useful.
Rest assured, for exposure times of several minutes, it is not necessary to be accurate to the second.
If you are using an ND filter, you will also need a calculator (or again, a similar application) to calculate the exposure time required for the picture.
What settings should I use and how do I shoot long exposures?
Now that the equipment is ready, let’s move on to shooting and the settings to use.
Day and night, you will use similar basic settings: lowest ISO sensitivity and low aperture.
Low ISO sensitivity for maximum quality
The higher the ISO sensitivity, the more sensitive the sensor will be to light.
This is very useful for using fast shutter speeds, but in our case, it’s not what we’re looking for.
On the contrary, we are looking for the slowest possible speed, so we will use the minimum ISO sensitivity of the camera (ISO 50 or 100, sometimes ISO 200).
Good news, this also has the advantage of guaranteeing us the best image quality.
Indeed, the more we increase the ISO sensitivity, the more the image degrades.
Low aperture for slow speed
Here again, while in normal times we often look for a large aperture to make beautiful pictures with a low depth of field, in the case of long exposure, we will look for the opposite: the maximum depth of field to extend the exposure time.
Indeed, a small aperture like f/16 – the diaphragm is closed and lets in little light – will allow us to leave the shutter open longer to get the same amount of light (the history of the tap and the bucket of water).
So why not choose a maximum opening of f/22? To avoid the phenomenon of diffraction.
At f/22, the image will not be sharper than at f/16, but rather the opposite: the sharpness is better at f/16 for most photo lenses.
Of course, if your goal is to make extremely long exposures and your only solution is to open your lens at f/22, do it rather than deprive yourself of it.
Shutter speed priority or aperture priority?
Both, sir! By choosing shutter priority mode, you’re the one telling your camera: I want to shoot at this speed, tell me the settings I need.
For example, if you want to shoot with a speed of 3 seconds at the end of the day, the camera will propose an aperture of f/22 because it considers that the scene is bright and compensates by closing the diaphragm.
In some cases, if the luminosity is too important, the camera will tell you that even at f/22 and 3 seconds your picture will be white, because it is overexposed.
By choosing the aperture priority mode, you can already choose an aperture close to f/16 and see the speed that your camera body indicates to you.
If the speed is too fast, check that you have chosen the lowest ISO sensitivity.
If it is, you’ll need to get an ND filter, as you’re probably in the middle of the day.
In order to guarantee the highest possible image quality and post-processing possibilities, we recommend that you shoot in RAW.
This allows you to correct the white balance, which could result in magenta or blue with some ND filters.
The RAW format also allows you to recover more detail in shadow areas than is possible with the compressed JPEG format.
On this subject, it is recommended to expose your photo for highlights in long exposure situations: it’s better to have blocked blacks than burnt out whites, as it is possible to recover more information in black than white.
A few tips to ensure optimal stability and sharpness
In Practical Wednesday #114, we gave 10 tips to improve the sharpness of your night photos.
As these tips apply mainly to long exposure photos, you should follow them.
For example, it is important to :
- ballast your tripod
- be careful of vibrations and wind
- Avoid touching the camera when taking pictures.
- disable lens stabilization if on a tripod
On DSLRs, it is also useful to lift the mirror before shooting.
This can be done in the menus or by using the camera’s Live View mode (which also allows you to check the focus by zooming in).
How do I make a long night shot without an ND filter?
Here’s a real-life example: You’re on a street at night and want to photograph the streaks of light from the headlights of cars passing in front of you.
After having installed your camera body on your tripod, you choose the following settings: aperture priority, aperture at f/16, ISO at 100 and your camera body tells you for example that it will take you 5 seconds to correctly expose your image.
In case you do not use an ND filter, you have nothing else to do but pick up your remote control key and trigger when a car passes by.
One thing to watch out for, though: focus.
In low light, your device may not focus properly.
In long exposures, it’s a good idea to focus accurately before you shoot, then take your hands off the camera and switch to manual focus.
This way, between shots, your camera will not have the laborious task of refocusing.
How do I make a long daytime exposure with an ND filter?
During the day, long exposure gives amazing results, but shooting is a bit more complicated to prepare because of the ND filter.
Here are the steps for shooting with an ND filter:
Set your camera to aperture priority with the desired aperture
- Choose the lowest ISO sensitivity
- Focus on the desired element without placing the ND filter in front of the lens.
- Note the shutter speed proposed by the camera for correct exposure.
- This is where it gets complicated.
- To make a long exposure with a slow enough speed during the day, you need a dense enough ND filter.
In other words, you can’t see through it, and the camera can’t see through it either.
This poses two problems that will have to be solved:
- the focus can’t be made through the ND filter
- the exposure measurement cannot be made through the ND filter.
For the first point, simply focus without the filter, switch to manual focus and leave it untouched.
For the second point, you will have to apply a simple mathematical rule.
Here is a summary table of different ND filters available on the market, with their attenuation factor and the impact on the light passing through the filter.
|Filter Intesity (X Number)||Optic Density||Stops Values||proportion of the ambient light that the filter lets through|
|ND 2x||0.3 ND||1 stop||50%|
|ND 4x||0.6 ND||2 stops||25%|
|ND 8x||0,9 ND||3 stops||12,5%|
|ND 16x||1.2 ND||4 stops||6,25%|
|ND 32x||1.5 ND||5 stops||3,12%|
|ND 64x||1.8 ND||6 stops||1,56%|
|ND 128x||2.1 ND||7 stops||0,78%|
|ND 256x||2.4 ND||8 stops||0,39%|
|ND 400x||2.6 ND||8 stops + 2/3 stop||0,25%|
|ND 512x||2.7 ND||9 stops||0,19%|
|ND 1000x||3.0 ND||10 stops||0,1%|
We can see, for example, that using an ND4 filter, only 25% of the ambient light passes through the filter, which is 4x less than without the filter.
With an ND8 filter, only 12.5% of ambient light passes through, 8x less than without the filter.
In order to obtain a correct exposure of the image, it will be necessary to compensate for this loss of light due to the filter.
The formula to remember is the following: multiply the shutter speed given by your camera by the attenuation factor.
This is the number given in the expression ND4, ND8 or ND1000 for example.
For an ND1000 filter, you will need to multiply the speed by 1000 to get the shutter speed you want to use.
Let’s take an example: without an ND filter, my camera gives me a shutter speed of 1/50s for an aperture of f/16.
With an ND1000 filter, I have to multiply 1/50s by 1000, which gives me 20 seconds (1/50 x 1000 = 20).
To properly expose the picture, I should therefore use an exposure time of 20 seconds.
Once the necessary exposure time is known, you will have to switch your camera to manual mode and transfer the aperture and exposure time (in our case, f/16 and 20s) to your camera.
Then, you just have to place your filter in front of your lens without touching the focus and then shoot.
Using multiple ND filters together
Several ND filters can be used together.
In this case, to obtain the attenuation factor to be used to calculate your exposure time, you will need to multiply the attenuation factors of your filters together.
Thus, an ND8 filter + an ND1000 filter gives a filter with an attenuation factor of 8000!
Subjects best suited for long exposures
Not all subjects are equal in front of the long exposure.
Indeed, to obtain an artistic, even minimalist rendering, it is important to photograph a moving subject, even if this movement is very slow.
Photographing water, whether it is the sea, a waterfall or a river, will give a very smooth, even milky result.
This result will be even more successful if you have a completely still area of the image in opposition, such as a pontoon, rocks, etc.
Clouds and the sky (at night with the stars) are also a very good subject for long exposure, as long as there is an element that does not move, such as trees, a building, etc., in opposition.
Lightning, fireworks, light (with lightpainting) and many other everyday subjects (daytime crowds) show a new facet with the help of long exposure photography, you just have to experiment.
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