Lighting Diagrams: A Powerful Tool for Studio Photographers

In the different off-camera communities I know, a real effort is put in accompanying each photo with information about its lighting. On the Strobist Flickr Group for instance, it is mandatory to describe the setup that was used in the photo caption.

This is truly a nice commitment in order to help others learning about lighting and I am the first to enjoy this, but I don’t find text descriptions appropriate for that kind of documentation. While this is probably the best and most direct way to comply to this rule on Flickr, I am surely not the only one to prefer something a bit more visual, as I have seen setup shots and lighting diagrams flourish along with those text descriptions. Not that much though…

A lighting diagram is a great tool to document a photo and–more specifically–the lights and modifiers used to create it. I am surprised it is not more widely used by strobists and/or studio photographers… in fact, I’ve found through my readings of forums and blogs, that not everybody seems to understand the benefits of lighting diagrams and how to use them properly.
This post will give you my understanding of this tool and some tips on how to get and communicate useful information through a diagram. Of course, I don’t mean to have absolute knowledge on the subject, but I do hope to bring some insights on lighting diagrams to those who are still wondering about their usefulness.

The first, obvious statement about lighting diagrams is that they document your photos. They will give you the position of the camera, the subject and the type of lights used to produce your photography. It’s interesting in order to understand lighting in a photo you didn’t make, but also to keep track of your own lighting setups. Do keep a file of your lighting diagrams as a personal reference to what you found works great with your own gear. It might especially help you to reproduce your setups if you’re learning lighting. Don’t forget to be creative and to try new things though! I’m not sure drawing diagrams and using the same setup over and over again will help you after some point :)
The second benefit I see to lighting diagrams is how they can help you settling things down before a complex shoot. We photographers are usually visual people, so drawing can be definitely helpful to fix ideas. And if you are working with an assistant, a diagram can sometimes be worth a thousand words to get things started. We’ve all seen how napkins can be used to that purpose!
Last but not least, one highly valuable outcome of drawing lighting diagrams is to be able to teach others how you built up the lighting that led to that special look in your photos. In doing so, you might surprise by the simplicity of a setup you used to achieve a complex-looking lighting. Or the other way round. But that’s no problem, as long as it starts a discussion, you are in a win-win situation: some people will learn from your technique and others may give you advice as well.

In order to have such discussions engaged, your diagrams have to carry a minimum set of information.
Of course the first piece of information you want to provide is the position of your gear, your subject and yourself. This, sometimes, can be enough. It mainly depends on how precise you want your diagram to be. Then come distances. Surely enough, distances are just an extension to how you positioned your gear on the diagram. Being precise is what changes the deal… At this point, if you are not familiar with the inverse square law, you might want to read Flash photography, and pwning the inverse square law by Dustin Diaz. Simply put, this law tells you that when you double the distance between your light and your subject, you loose two stops of light on your subject. This is a first hint at why distances are important on your diagram. However, as you can guess, one could possibly achieve the same results as yours without conforming to the distances you used, by decreasing or increasing light power to keep the same exposure. What inverse square law doesn’t influence though, is how soft your light is and how wide is the angle it covers. As you know, the bigger the apparent light source is, the softer it looks. Your diagram will show this crucial information by providing relative distances between your light sources and subjects that are accurate enough.

Notice that I am talking about relative distances here: how far is your key from your subject, or how farther is your rim or fill from the subject, and so on. I think “being relative” is the key when working with lights: almost everything as to be thought in relation to your subject, to the ambient light, to other lights… So, the same principle of relative distances applies to light powers you used in your photo.
We are not naturally used to describe light as an absolute value. You’d rather say “this room is dark”–by reference to daylight or to what we usually consider a properly lit room–than “wow, it’s barely 150 lux in there!”. It works exactly the same with light levels from your light sources, and David Hobby explained it better than I could do in his article Strobe/Ambient Balance: A Shorthand Way of Thinking.
He says:

“It’s the relationship between the different light levels that is important”
You shouldn’t need more to accompany your diagrams than explaining those relationships between your lights, using the key light as a reference exposure for instance. Giving absolute information like “Flash #1 at 1/8 power” could in fact be error prone, as this setting was valid for your own gear and maybe only in the context of the ambient light you were shooting with. This statement is certainly a bit extreme, as absolute values do give an indication on how much light you used in your setup, but it will stay relative to your own flash full power, which will vary from gear to gear.

So now you have it, this is how I see lighting diagrams: as a great tool to document your photos in order to keep a record of your lightings or to teach them, by providing useful information that remain adaptable by any photographer in most situations.
In the idea to help photographers (including me) using lighting diagrams a bit more, I’ve founded Sylights with a friend of mine, Pierre-Jean. Our goal is to provide you with means to facilitate diagram creation and sharing, and you’ll find this in the form of an online diagram editor at of today, we are releasing Sylights as a preview version: it still needs improvements and all the features are not ready yet, but we do want your feedback while we continue developing the website.

We will keep you informed of the evolutions here, but also on twitter and on our Facebook page. Please feel free to use those to communicate with us as well!

Comments are opened below if you feel like giving us your first impressions :)
Thank you!