A great skill to develop as a photographer is learning how other people make photos. You don’t always have the original photographer available to tell you how the photo was made, or behind the scenes videos and lighting diagrams to explain it all. Sometimes you have to be able to look at photography and judge for yourself. We call this reverse engineering.
Instead of building a photo from scratch, you take the final product and deconstruct it into elements. Like any good engineer, understanding all the parts and how they interact takes some practice. In time, you’ll be able to look at a photograph and quickly be able to make an educated guess as to the type of lens used and the kinds of lighting in play.
Here are five things to think about when reverse engineering photos.
You can see highlight areas, shadow areas and specular highlights in the eyes to read the light sources.
Distance to subject
First, use visual cues to determine the focal length of the lens. Does it look like a wide angle lens? You can tell if the setting is a tight space but you can still see much of it. You can also tell if there is distortion — straight lines look slightly curved or shapes look out of proportion. Does it look like a standard 50mm lens? This would be generally the field of view if you were looking with your own eyes. There is no distortion around the edges and no peripheral view. Is it a telephoto lens? Portraits of people will typically have flat, blurry backgrounds and no visible distortion. Think about the possible places the photographer could be standing based on the information in the photo. This will help you figure out how far away the subject is and what kind of lens the photographer is using.
Direction of light
Light is what makes photography what it is. This is what separates a good image from a great image. So, we spend most of our time reverse engineering the lighting.
The easiest part to spot is the direction of light. For a portrait, if the left side of the face is light and the right side of the face is dark, we know that the light is coming from camera left. If both sides are even, we can guess that the light is coming from right behind the camera.
The quickest way to determine the light’s direction is looking for shadows. Shadows under the eyes and chin mean the light is coming from above. Shadows that lean to the left mean the light is coming from camera right. The shape and position of a catchlight in a person’s eyes can also give this away.
Which way are the shadows pointing? This indicates the direction of the light.
Intensity of light
There are often multiple light sources. Traditionally we use a main light, fill, light, and backlight and/or hairlight for portraits. Look for the brightest area in the photo. This will help you determine which of the lights is brightest or has the highest intensity. Think about the lighting in terms of ratios: if the main light is on full power, is the fill light at 1/4 power? Is the backlight at 1/8 power? What are the relationships of intensity?
Shape of light
Lighting takes on different shapes depending on what it is coming from, going through or what it is bouncing off of. We call it soft light if it comes from a relatively large light source relative to the subject — we call if hard if it comes from a small light source.
Again, look at the shadows. If the shadows are soft and difficult to tell where they start and end you are probably looking at a large light source. If the shadows are hard and create distinct lines on your subject, you are probably looking at a small light source. Of course, the size is relative to the distance of the subject. The sun is very large but is so far away that it appears to be small, creating hard shadows. A shoot-through umbrella is small, but placed right next to a subject appears to be large.
Color of light
Lastly, we can tell the color of the light pretty easily with some basic experience with light sources. Light color is on a spectrum from cool to warm. We know that the daylight goes from cool before the sun comes up, to warm in the morning, neutral in during the day, warm at sunset, and then cool again after the sun goes down. Judging by color temperature we can also guess the position of the sun. For studio lighting , which is daylight balanced, we can tell if gels are being used by different color temperatures in different parts of the scene.