I must admit that I keep getting confused about specular light vs diffused light relative to soft light vs hard light. It is especially diffused light and soft light that I mix up, but let me give it a try.
If you see tarmac on a sunny day, the tarmac does not reflect very much light (it tends to absorb the light and get warm for that reason), but as soon as you have rain hitting the tarmac, the water on the surface will start reflecting the light and will do so in a way where the incoming light is reflected pretty close to how it arrived. So all of a sudden the reflections of the light in the water is very bright – I am sure you have tried this driving home late at night; the headlights from the oncoming cars is suddenly a nuisance because the rain set in.
So for me specular light is very much about the “dynamic range” of how the light is reflected on a surface. If the brights are very bright and the darks are very dark, then the light is specular. Remember here that the nature of the light is assessed looking at how it is reflected by the subject.
Diffused light however will have much less contrast between light and dark. It tend to be more “shades of grey” than black and white, to put it simply. The subject appears more evenly lit.
One of the tests that I often do when reviewing a lens is to shoot a piece of tinfoil curled up into a ball. Such a subject will yield specular light where the brights are very bright and the darks are very dark; excellent for revealing issues with chromatic aberrations, which you will often see where the contrast between bright and dark meet.
Although Latin will never be my forte, I seem to remember that photography stems from the words “writing” and “light”, i.e. writing or creating with light. So bearing this definition in mind, does low light photography then make any sense? In a word: Technically: no, emotionally: yes.
Signal to noise
Signal to noise. Sounds complicated, right? And it is, if you want to be an engineer and dive into this interesting concept. Lots of math and complexity. But for us photographers, all you need to know is that light is a signal and that your camera is a system that inherently holds or produces noise. So there is a balance between the input in the shape of light and noise during the production of the output, the image. That balance is signal to noise. And the stronger the signal is relative to the noise, the better, i.e. the more clean the image will appear.
When shooting in low light, the signal to noise ratio is appalling! Your camera struggles to “see” if there is light or darkness, and it makes mistakes! And the mistakes show up in the shape of grain and noise and washed out colors. The camera sensor simply gets so little light, that the noise is as strong as the light, and hence the sensor starts mistaking noise for light. And that is not good.
A night out.
So the obvious solution here is to add light – a big fat flash that will lighten up half the city and take out the noise, right? Well, right from a technical perspective. But people sitting in a dimly lit restaurant may find that this is exactly what will break the cosy atmosphere and you will not capture the emotion of the scene, as the added light ruins it all.
A rainy evening during winter time. Not much light here.
So the way forward is to find a way to capture the scene with very little light, and as with so many other aspects of photography there is no silver bullet. You have to find the optimal compromise.
What to do
First of all you need to make sure you get as much of the ambient light in the scene into your camera, so the faster your lens is (larger aperture) and the larger the camera sensor is, the better. Just like a big bucket gathers more water when set out on a rainy day than a small bucket, your camera will gather more light the larger the surface to gather it. And here the “size” of the (fast) lens and the size of the sensor is a remedy. But it comes literally with a price, and full frame glass is a lot heavier than say APS-C glass.
Here a flash cannot help much and would ruin the scenery!
Your next friend when there is little light available is time. The longer you can let the shutter stay open, the more light will be gathered obviously. But with time comes two new enemies: camera shake and motion blur. You can use both camera shake / movement and motion blur for artistic purposes, but if not, movement while the shutter is open is not your friend.
Camera shake can be countered with a tripod or maybe just leaning the camera towards something stable. When I am in town at night, I often use lampposts or other stable objects to give some level of stability to the camera. Next, you can invest in a camera (or lens or both) that has image stabilisation. This helps a lot and has made it possible for me to shoot sharp handheld images with shutters open at 1/4th of a second – something that would be completely impossible without stabilisation.
Restaurant at closing time.
Motion blur is when your subject moves while the shutter is open. It can be hard to avoid when you are shooting fast moving objects at night e.g cars on a highway. One technique is to follow the subject with the lens (panning), so the subject is kept in the same position in the frame and everything else gets blurred. This requires some training, but is great fun when you succeed! If you just want to take pictures of people in a restaurant, keep an eye out for an arm moving or a glass being lifted – maybe that is not the right time to hit the shutter!
Cranking up the ISO is what many do! If not deliberately, then because the camera is in some automated mode where it struggles to find a way out! Shooting at high ISO is often necessary in a low light scene, but be aware that in digital photography the sensor has the sensitivity that it had when it left the factory! When you turn up the ISO value, it is factor applied to the readings of the sensor. You can see this as camera internal post processing being applied. So both signal and noise will be amplified. It is just like an old tired analogue radio with a muffled sound and bad reception of the signal: turning up the volume will not make it sound better, as both music and noise is amplified. So try to limit or cap the use of ISO – I normally do not go beyond ISO 3200, but a “max acceptable level” varies from camera to camera.
Finally, it is not only the exposure that struggles in low light, also your focus system will struggle. You may find that your otherwise super stable and fast (daytime) auto-focus system starts hunting and acting weird. And images out of focus may result. The remedy here is manual focus. Yes, I know, if you rely on auto-focus in your daily work, switching to manual focus is not what you hoped for. But it may be the very thing standing between you and some great low light images. So use all the focus aid systems available in your camera: zooming in in the viewfinder or focus peaking highlights or focus confirmation dots. Take all the help you can get as you take control of the focus.
Next step
I know that photography can be a pain: you were hoping for a quick fix only to learn that photography as per usual is about finding the best compromise. But don’t give up: low light images can be very rewarding and capture a tranquil scene or sentiment that no other type of photography offers. So I hope you will take up the low light challenge – the rewards on the other side is worth it.
Remember Tom Hanks’ performance as Forest Gump? Outstanding! Remember the supporting actors? Robin Wright as his girlfriend and later his wife? Gary Sinise as his commander and later his friend and best man? Although Tom Hanks clearly steals all the light, the supporting actors are just as important to make a great movie.
Light is a bit the same way. The main light or the key light is of course the starring role. But the fill light is also important to make the leading character shine.
Message from the dark side
Where the light is the brightest, the shadows are the darkest. Wise words that I think are intended to give us hope in troubled times, and not fly too close to the sun either. But it is also very true in photography. When you have lots of light hitting your subject from a specific angle, it will – unless the light source is extremely big like the clouds on an overcast day – give shadows in the opposite direction from where the light originates.
Every time a scene is lit with directional light you will be met with this simple fact: bright areas and dark areas go hand in hand like horse and carriage. This is where fill light comes to the rescue: it is simply light sent from the opposite direction of the main light.
Single light source on a ring. Notice the shadow top right of the ring that reveals the direction of the light.
Mood
When you have a high contrast image with bright brights and dark darks, your viewer may find the image to be a bit unsettling. The fill light can fix this: it reduces the dynamic range so the histogram of the image is more centered than without the fill light. Many focus on the fill lights role to reduce or eliminate shadows, but it actually has a major impact on the expression the image gives – it has a more positive or uplifting vibe. And especially when it comes to portrait photography, this is a key feature.
How to?
The simplest remedy for creating fill light is to place a reflector or just a white plate in the opposite direction of the key light. In the example below you will notice how the shadow top right of the ring has been significantly reduced due to the reflector introduced. Notice that the key light can be daylight coming through a window.
Adding a reflector helps reducing the shadow from the ring, but the challenge with using a reflector is that it can be difficult to control the strength of the light (you can move it closer and further from the subject, but it is not always an option if in a small room).
The challenge with fill light is to find the balance between the fill light and the key light – if the fill light is too strong, it will introduce a new set of shadows which is certainly desirable. To balancing the key and fill light is – well, key!
Adding a second light source helps. You can see the shadow of the ring top right is now gone. The light is so strong that it now causes the ring to reflect in the table, so turning down the volume could yield a better result. My assistant came to the scene and did not allow me to pursue that idea!
If you fill light can be controlled precisely by you, either the strength of a flash or steady light, I find this to be the easiest way to find a good balance between key and fill light. With a reflector or reflecting surface, you may need to experiment with the distance to the subject to find the right balance.
Many associate silhouette photography with shooting into the light where the dynamic range of the scene forces both bright areas to be blown out and all details in the shadows to be complete gone and pitch black instead. But take a look at the image below – it is possible to make silhouette photography without shooting into the sun!
Although there are no super bright areas in this image, the details in the dark of the branches are completely gone and you only see the branches as silhouettes.
But otherwise silhouette photography is, as the name says, shot in a way where the subject only stands out as a silhouette. A lot of detail and information is lost about the subject or subjects. And this is on purpose to bring the structure or the shape of the subject in focus.
Image left, histogram right. Notice how the histogram touches the left hand side, indicating that details are lost in the shadows.
Although some details of the lamppost is provided, the tree and the lamppost stand as silhouettes against the moon top left. Notice how the image plays with lack of depth information.
Another often overlooked feature in silhouette photography is that it is 2 dimensional. Often photographers add depth in an image by having something both in the foreground, middle and background to compensate for a photo being a 2D representation of a 3D world. Silhouette photography deliberately seeks a more 2D expression just like a Chinese shadow theater.
A more classic silhouette photography with lots of dynamic range. The houses are reduced to black shapes and so is the tree. Morning sun.
You can try out silhouette photography: Shooting into the sun is the “classic” way of doing it, and your camera will often not be able to capture the dynamic range of it all and hence create an image that looses a lot of detail in the shadows – just like you want it to. If your camera has an metering setting that allows you to expose for the highlights, you can try this option – it is excellent for shooting silhouette photography also when you are not shooting into the sun.
Light diffuser defined and a few examples to illustrate the use.
A light diffuser is anything that spreads out the light to cover a larger area or space than it would otherwise. The point is to make the light source bigger relative to the subject – the bigger the light source is relative to the subject, the softer the light is.
If you shoot with flash sitting on your camera, a way to diffuse the light is simply to point the flash upwards or sideways, away from your subject, and let it bounce on the ceiling or wall, so these are now your light source and not the flash itself. You can also get a little white cap to put on your flash that in itself enlarges the area of the flash light, in case you don’t want to loose so much power in the light as you do when you bounce it against a wall.
If you are outdoor shooting at noon on a cloudless day, the sun makes very hard light, i.e. the transition from light to dark happens very suddenly and you only have extremely light and extremely dark and very few shades in between. If you diffuse the light from the sun by hanging a big white sheet between the sun and your subject, you will find that this diffuses the light greatly as the light source is now the entire sheet rather than a very, very small dot very far away (also known as the sun!).
The golden hour is the time just before or just after sunrise or sunset. The light is very different from the rest of the day, as the sunlight has to travel through the atmosphere “sideways” and hence travels a much longer distance than if the sun is right above your head in zenith during noon of day. The light during the golden hour has a much more red cast that the rest of the day, the light hits subjects sideways and it is much softer light with gentle transitions from light to dark.
The sun at noon sends its light waves directly downwards and hence the shortest distance through the atmosphere. Early morning or late evening, the light travels much longer through the atmosphere.
In the image below, other than clearly having a red cast, the light travels sideways and lights up the side of the train to the right. During mid day the light would obviously have hit the top of the train which is a far less interesting view.
Also during the golden hour, the power of the sun is significantly reduced, and especially in the morning you can find that mist and traces of light are much more frequent than during the day:
Rays of light travels though the treetops on a misty morning.
So, in conclusion, if you can set the alarm clock to get up in the morning or you have the endurance to go shooting during sunset, you will capture images that are very different from what you can shoot during the day. The golden hour term is no exaggeration.
If you heard that soft light is better than hard light, it is likely that statement came from a portrait photographer. Soft light is in general perceived as giving a more flattering look, where the light wraps gently around the subject.
But what is soft light? Soft light is light where the transition from bright to dark happens gradually, i.e. there is a lot of mid tones in the transition zones. Take a look at this pencil that I placed in my window space on an overcast day:
On a cloudy day, the sunlight is made into a massive light source as the light is spread across the vast area of clouds. In other words, the light source is huge! Notice the shadow at the tip of the pen? It is hardly there. You see a shadow where the pen rests upon the AirPod charging case, but the rest of the shadow is one big zone of tones of grey.
Now look at the next example, where I placed the pen under a reading lamp. A light source much smaller than the light from the clouds:
Suddenly you can now clearly see the shadow of the tip of the pen. If you look carefully, there still is a bit of grey zones where the white from the case transitions into the dark of the shade, but it happens much more abruptly than in the former example. The reading lamp as light source is simply much smaller.
Finally, the most harsh and brutal hard light I could think of: a flash held some distance from the subject with no diffusion at all! The bare bone flash activated here – you can see the flash light reflected in the yellow of the pen:
Notice the reflection of the flashlight on the pen.
In this final example, the transition from light case to shadow from the pen happens almost from one pixel to the next. Okay, maybe not so suddenly, but I hope the difference is clear.
It all comes down to the size of the light source, relative to the size of the subject. The bigger the light source, the softer the light.
So what should you use? As you may have guessed, my annoying answer is: it depends. Yes, for portrait photography you probably want to show the more flattering side of your subject and use flattering light. But hard light works fine as an artistic expression or to simulate a sunny day with no clouds at high noon. So use the softness of the light as a tool in your toolbox and use it deliberately, instead of just saying “soft light is the only light that works”.
You may have heard of the inverse square law and seen some posts and videos going through the technical aspects of the inverse square law. I will try to stay clear of the technical aspects here, and simply say that light falloff is the fact that the intensity of the light drops fast, as you move your light source away from your subject.
Quite counter intuitively, the light falloff does not happen in a linear way, rather it drops like a stone! In the beginning that is. So if you move your flash from 1 foot away from you subject to 2 feet away, the intensity of the light has dropped not by 50% but by 75%! So by doubling the distance, you only get a quarter of the light on your subject. This is what the inverse square law is all about: the non linear relationship between light intensity and distance. You can maybe see it in the picture below, where I have taken a LED light and put it close to a white wall:
Good news is that the curve flattens quickly, so 3 feet away the light has dropped to 11% of the original light, 4 feet away it is 6 % and so on. So if you are very far away from your light source, moving one foot closer or further away means very little.
The intensity of the light drops dramatically as distance to the light source increases.
In the example above, had there been a 4th cup, it would get only 6%! If you draw a curve of the intensity of the light as a function of distance, you will get what I call a hockey stick curve – it drops a lot as distance increases only to flatten the more the distance is increased.
If you photograph a group of people and light them up using a flash, the ones standing in the rear will get a lot less light than the ones standing in the front, if you have the flash (or modifier) close to the front row. The solution is to move the flash further away from the subject to make the relative drop in light less. The price you pay is that your flash will need to work harder and that the light is less soft.
You can use the light falloff to produce a grey or black background, even if you have a white backdrop. Just make sure the distance between your subject and the backdrop is sufficient, then the light falloff will take care of “dimming” the backdrop to grey or even black! See the examples below, where the only thing changed is the increased distance between subject and the backdrop:
Here some light is still reflected from the backdrop. But not much, hence the grey color.
Here the background is black due to light falloff. But IRL the backdrop is pure white!
Using a flash and the effect of light falloff, I was able to make these withered leaves stand out on a dark background. If you are thinking that it did not look like this IRL, then you are absolutely right!
