Light is of course important when taking photos. Without light, no photo.
There are several aspects of light that are important:
In all situations, it is important to have sufficient light. The more light you have, the more light reaches the sensor, and the more information the camera can use to produce a nice picture.
A lot of light means the shutter doesn’t need to be open very long, and you avoid motion blur.
If the light is very weak, the photo will be covered by ugly dots that are lighter or darker than their background. These dots are called “noise.” They
come from interference from the camera electronics. Sufficient light means that interference from the camera electronics is drowned by the photons from the outside.
In most situations, there is no such thing as “too much light” in a scene. A mobile phone camera can compensate for basically any amount of light in any scene. This doesn’t mean that too much light cannot be a problem though. A mobile phone camera can easily run into problems with high contrast, where there is much more light in one part of the scene than in other parts, like any time when the sun or a very strong lamp appears in a photo.
Find a fence or a tree a sunny day. Its shade will be very dark with sharp edges. If there are hazy clouds, the shadow will look less prominent and the edges will be blurry. By completely overcast weather, there is no shadow at all.
The bigger the light source, the less prominent the shadow. By overcast weather, light comes from all over the sky. By sunny weather, light comes from one single point – the sun. (The sun is of course huge physically, but it is so far away that we can treat it as a point.)
When one takes a photo, this is something to consider. If you want stark contrasts, try to shoot when there is one small light source. If you want a more even distribution of the brightness, try to shoot when there are big light sources.
To achieve big light sources, you can use plenty of things: clouds, reflections on white walls, ceilings – anything that is big and that creates or reflects light efficiently.
To achieve hard light from one light source, make sure that the light source you use does not have a lot of competition. If you use a single strong lamp in a room with white walls, the reflections from the walls will compete with the light from the lamp.
If there is a red sofa or a bright green wall in the room, there will be light from those directions in those colours. That can create a nice effect, but it may also be the exact opposite to what you want to achieve.
Experiment: place one or several strong lamps in a room. Take a photo of a subject in the middle of the room and see how you can change the light by moving the lamp around and point it at different directions.
Direction of Light
As a child you may have tried to frighten your friends holding a torch under your face. This creates unusual (and somewhat scary) shadows on your face. This kind of effect can be used for other things than to frighten children. If you take a portrait of someone at sunset (or sunrise, if you are an early bird) you can see how the face looks different depending on where the light comes from. If the light comes from the side, irregularities in the skin will be very visible, and half the face will be much darker than the other half. If the light comes from behind you and directly onto the face of the subject, then hardly any shadows at all will appear, and the face will look flat.
This is one reason why integrated flashes in cameras are of limited value. People are tempted to use them to lighten portraits, but as the light comes from the camera, there will be no shadows at all, and the portrait may look bland and uninteresting.
Colour of Light
All light has some colour. Most light sources consist of many colours at the same time. Pure white light contains all the colours there are. An experienced artist can predict the effects of different colours, and they can create amazing results using this knowledge.
For most of us, the colour of artificial light is something that creates more of a problem than any value. Light bulbs create an artificial yellow hue on subjects. Neon creates other colours. Most phone cameras have software to sort this out. If they have a setting to correct it manually, it is called “white balance.” Sometimes, the camera fails. This may be the case if you are in a room with for example red walls, red carpet and red furniture. The camera may decide that the light is so red that it must be wrong, and if turns the photo less red than you would like.
If this is the case, and you can configure white balance, try different settings and see if you can get it right. If you have no such settings, you can often fix the colours afterwards in post-processing. If the colour is wrong, but not important for the photo, you can try turning the photo black and white, and see if that is acceptable.
However, light can cause other kinds of problems.
When the sun’s rays or some other strong light hit the camera lens directly, it is very likely that there will be an imperfection on the photo in the shape of a light grey blob. The obvious answer is to avoid pointing the camera at the sun or other strong lights, but that is not always an option.
To avoid flare, it is important to have a perfectly clean lens with no fat or other substances.
Sometimes, when you point the camera towards a subject close to the sun, you can change position, so the sun isn’t in the frame itself. However, that often doesn’t help, as the sun nevertheless reaches the lens from the side. In this kind of situations, one can often block the sun with a hand or some other object. This is one of the reasons big camera lenses often have a lens hood. However, you do not have to have a hood that goes all the way around the lens. The only thing that is needed is something that puts the lens in shade of the sun. In theory, it could be enough with a small coin in the right position. Unfortunately, “the right position” can be difficult to achieve. You can try holding your hand, so it blocks the sun. You can also try to move the camera, so some other object blocks the sun, like a tree or a window frame.
In this photo, there is some sun flare in the upper right. It does not add much to the composition. It could probably have been avoided by the photographer, if he had held his free hand to shade the lens from direct sunlight.
Another problem with too much light is high contrast. If you take an outdoor photo in the middle of a clear day, a lot of things will get plenty of light. However, in the shades, other things will get much less light, and they may show up as black on the photo. To avoid this, you can often point the camera at dark portions of the subject, like the dark side of a sunlit building. If the conditions are right, the camera will readjust, and the dark parts look nice. However, it is very likely that the sunlit parts now appear completely white, on the photo.
This problem of high contrast between light and dark is bigger on mobile phones than big cameras, which have bigger sensors that capture more light. But even big cameras have problems in this kind of situations.
If your mobile phone can take RAW photos, it may be easier to fix the problem in post processing with them than with JPEG photos, but it is not
certain that there is much of a difference. (To know if your phone can take RAW photos, check the manual or search the internet.)
Another way to limit the problem of high contrast is to frame the photo so all the important parts are either in the sun or in the shade and accept that the other bits are blown out. One can also wait until the sun is in a better position, where the problem is less visible.
In some cases, like with architecture photography, one can often limit the problem by coming back another day, when it is cloudy, and there is less outdoor contrast.
Depending on the size of the parts in the shade, it is also possible to use artificial lighting. The flash of mobile phone cameras is not necessarily of much help, but in this kind of situations it may be better than nothing.
Without investing in commercial spotlights or reflector screens, one can get some result by using other light objects to reflect the sunlight. Something as simple as a white t-shirt or a white jacket placed as a reflecting white area can light up someone’s face.
If you need to take a photo of someone with the sun in their back, you can try to place yourself in front of a white wall, so the white light from the wall reflects in your subjects faces.
Another option when it comes to high contrast scenes is HDR or “High Dynamic Range.” It is not a pure camera functionality, but it is so common in mobile phone cameras today that it is difficult to ignore.
What HDR does is to take a number of photos at different exposures. One at high exposure, that works with light subjects, one with low exposure that works fine with dark subjects, and often one or several photos with exposure in between. Using software, the camera then merges the different photos to one single photo with the best bit from each photo.
If you have a high contrast scene and a camera with HDR, try it. Just activate it and shoot.
You may be happy with the result, but one should pay careful attention to the final picture. HDR has a tendency to distort colours and shades in the photo, and it may not look natural. If the photo is fine for your purposes, use it. If it is not fine, you can try changing colours in whatever image processing software you have, and as a last resort, change it to black-and-white, and see if that looks more natural.
Really high end big cameras rarely have an integrated flash. There are reasons for that. One important reason is that the light that comes directly from a single point on the camera itself rarely gives any pleasant light. It washes out existing shadows, so the photo becomes flat, and if the shadows the flash gives are visible, they are very sharp. For high end photography, external lighting is often needed. Secondary flashes on tripods, spotlights, light screens and so on.
That is difficult to achieve with a phone camera, and it mostly defeats the purpose of a phone camera. If you anyhow need to carry around heavy lighting gear, why not carry around a big powerful camera as well?
Nevertheless, many mobile phones have integrated flashes of some kind. If the choice is between taking no picture at all, or one with an integrated flash, by all means, try the integrated flash.
To avoid some of the bad effects of an integrated flash, you can try some tricks.
Use a reflector of some kind, to direct the light so it doesn’t fall straight onto the subject. For example, use the metal part of a key or a spoon to make the light hit a white wall or the ceiling or the floor before it reaches the subject.
This will create a softer light from another direction that (if the flash turns out strong enough) may make the subject look interesting – sometimes in a good way.
If you have to take a photo of someone outside, it can also be good to try to use the mobile phone’s flash as a “fill flash” when shooting against the sun. This will make the details of the face appear like more than a black silhouette, at least if the flash is strong enough. In this kind of situations, it often helps to tap on the person’s face on the screen, so the camera knows it
should adjust brightness to the face, even though this will make the background heavily over exposed in many situations.