To create interesting light, you also need to create interesting shadows.
Syl Arena in The Speedliter’s Handbook.
As I read some of the questions posted on the various forums that I frequent, I often see a number of questions regarding the purchase and use of flash. These questions are often very similar:
- I am debating whether or not to buy a flash or a new lens, which one should I buy and why?
- I have a built in flash, do I need a stand-alone unit?
- I want to buy a flash for my camera (Canon, Nikon, Minolta, Sony, etc.), which one should I buy?
- What is TTL (ETTL) and why do I need it?
The list goes on. You should note however, that there are a lot of cameras, of the so-called point and shoot variety, that will not accommodate an additional flash unit. You need to have a hot-shoe on your camera for it to be capable of handling a stand-alone or external flash unit. There are also some DSLRs that do not have a built-in flash, therefore, they must rely on an external flash for additional light when required. In what follows. I am going to assume that you opted for the flash and not the lens.
What is it that a flash does?
This may sound like an unnecessary question, but a lot of photographers who are just starting out do not fully understand what a flash does for them. I think this is the first thing that any photographer contemplating the use of flash has to know about – what does it do for me? The major purpose of a flash is to illuminate a dark scene. It can also be used to capture quickly moving objects, by helping to freeze the subject when the flash is triggered. It can also be used to change the quality of the light.
One thing to also understand, is that flashes do not really illuminate your subject, but rather they provide light that bounces off the subject and returns to your camera. Thus the further you are from your subject, the more powerful your flash has to be. Yes, you can change your ISO and your aperture, but at some point, your flash will not provide the illumination you need to get enough light back to your camera to properly expose your subject. So, if you are wondering why your flash didn’t provide enough light for that family portrait during last year’s reunion, that is probably why – you were just too far away for it to do its job.
Another aspect that a beginning flash user has to understand is a bit of physics known as the inverse square law. This isn’t as overwhelming as it sounds. It simply means that if you increase the distance of your flash from your subject by twice, then you decrease the amount of light hitting the subject by a factor of four. For example, if you take a picture of your subject from 1 metre and then take a picture of the same subject from 2 metres, the amount of light falling on the subject in the second picture will only be one-quarter, or 25 percent of the light falling on the subject in the first picture, rather than only half the amount, which you might conclude is the answer because the subject is twice the distance away at 2 metres. If this is a bit confusing, don’t worry, just remember that as your subject moves away from your flash, the amount of light reflecting from your subject drops very quickly.
I already have a built in flash, why do I need an external one?
If all you are going to do is take snapshots of your friends and your pets, then the built in one is probably fine. It does not give you much light and what it does give you is often quite harsh. On the plus side, it is built in, thus it goes everywhere with you and it does not add weight to the camera bag. If however, you want to have more freedom with your flash unit, e.g., you want to be able to take it off the camera or bounce it off walls, etc., or you simply want a more powerful flash unit, then you will need an external flash. Furthermore, an external unit will allow you to soften the flash by attaching various types of diffusers to it.
What type of flash should I get?
This is a question that has no simple answer. A lot depends on what you are going to do with it. A flash is one of those accessories that will outlast your camera, in fact it will probably outlast several cameras. My advice is not to go for the less expensive compatibles initially, but to get one that is made by the camera’s manufacturer. This does not mean that you have to get the top of the line, unless you think you will need all the features that it provides. Most manufacturers make a variety of flash units and often one of their mid-line units will provide what most photographers need. The reason for this recommendation is that the manufacturer’s flash is made to work with the electronics of your digital camera, whereas, while some of the compatibles may work, they may not offer all the functionality that the manufacturer’s does. If you are simply going to take family pictures on birthdays and holidays, then a mid-line model will probably be more than adequate. I would also recommend that you get one that has a tilting and swiveling head as this gives you more freedom in doing things like bouncing the flash off ceilings, walls, or diffuser panels.
If you are really going to get into flash photography (I mean really, really get into it) working in areas like macro photography, low-light photography, light-painting with flash, etc. then you will probably go for one of your camera maker’s top line units.
What is TTL or ETTL and why do I need it?
Some of the terminology that the beginning flash photographer will encounter are the abbreviations TTL and ETTL (or eTTL). These acronyms, used mostly by Canon, are short for through-the-lens and evaluative-through-the-lens respectively. They refer to a technology that allows the camera to work with your external flash in a more or less automatic mode. Nikon uses the term iTTL, or intelligent-through-the-lens to describe its flash technology. Canon now uses ETTL II technology, which is simply a software improvement in their original ETTL system. Other manufacturers use similar technology.
In its various implementations, ETTL uses a preflash, which is almost invisible, to give information to both the camera and the flash that enables them to make the proper exposure based on this reading. For example, ETTL is smart enough to know that, if the ambient light is bright enough, it will adjust the output of the flash downward to provide a fill-flash exposure. This built-in intelligence provides for better images when using flash.
Third Party or Compatible Flash Units
Previously I suggested that, for those just starting out in flash photography, they stick with a unit made by their camera manufacturer. This does this not mean that you should ignore third part external units. There are at least 6 different companies that manufacture flash units that are compatible with cameras made by Canon, Nikon and others. These carry brand names like Metz, Sunpak, Vivitar, Sigma, Nissin and Yongnuo. These are the ones that I am aware of at the time of writing, so there may be others. In my opinion, these are all suitable brands if you are going to purchase a second flash. Their manufacturer often makes different units for different requirements, so the choice would be based on your needs for a second unit.
Where do I go from here?
There are a number of books that have been written on flash photography. If you check the web site of a book retailer such as Amazon, Chapters or W.H. Smith you will find a number of titles. For general references, there is a book by Bryan Peterson, Understanding Flash Photography: How to Shoot Great Photographs Using Electronic Flash. There are also specialty books such as Flash Techniques for Macro and Close-up Photography by Rod and Robin Deutschmann. Flash use in portrait and wedding photography is covered in a number of books by various authors, but since I am not a portrait or a wedding photographer, I hesitate to recommend any particular one. The Canon flash system is covered in books such as Syl Arena’s SpeedLiter’s Handbook and the Nikon system is covered by Stephanie Zettl in her book Nikon Speedlight Handbook.
I would encourage you to explore the many possibilities for the use of flash in your photography. Experiment with a lot of different things and remember you can do that because digital imagery does not cost you anything except your time and investing some of your time in your photography is always a good thing.