Portable flash units have come a very long way from the days of the ever popular Vivitar 283 and the potato-masher Honeywell and Metz units. Although the earlier units had some level of automation, it was limited to what the flash could do on its own.
The new generation of flash units from the camera manufacturers takes the automation to the level of integration. The camera and the flash unit(s) work as one, freeing the photographer from much of the tedium of flash setup and synchronization. Both Nikon and Canon systems include several dedicated units that can function with amazing ease and capability. The downside of this super integration is the intimidation that may arise from reading the flash manuals. They are chock-full of information, settings, capabilities and also written in a technical tone rather than what would be an easy set of instructions to follow.
To ease the way into single and multi-flash photography using these super-capable units, I recommend a book by Lou Jones “Speedlights & Speedlites”. The book covers, in a color-coded style, both the Nikon and Canon flash systems. Interestingly, the book has two chapters. Chapter 1 deals with “one-flash” photography, Chapter 2 handles two or more flash setups.
It has many examples with diagrams and flash settings. It is an excellent read and a reference on the matter.
Being a Canon user of many years (OK, decades!), I am more interested in detailed explanations and capabilities of Canon gear. Not surprisingly Canon provides some excellent tutorials and information on Canon flash photography. Surprisingly, however, they make it convoluted to find this information even after one arrives at the related site. To save you the confusion (or to hide my thick-headedness) I will give you below links to specific pages where you will find much information on this subject. I am sure Nikon has similar resources for their users as well, you are on your own there. If you also own a new generation Canon cameras you are in for a treat; much of the flash control can be handled directly on the camera menu. This is far easier than trying to remember which button activates what, when, and when to turn the dial to make adjustments on the flash units.
(Canon moved the following learning resources and some may be available for a few. The links below will most likely take you to Canon learning site. Search as you please. Sorry for the missing direct links, beyond my control! November 29, 2018)
- Flash Work you will find here general information on Canon flash systems and use
- Fill-Flash use with EOS cameras and speedlites, a self-explanatory title
- Bruce Dorn Speedlite Videos, Part I: External Speedlite Controls A video tutorial
- Bruce Dorn Speedlite Videos, Part II: External Speedlite Ratio Controls The second part of the above
- Speedlite Tip Series, Part 1: Choosing the Right Flash
- Speedlite Tip Series, Part 2: Beyond the Instruction Manual
- Multiple Flash and Lighting Ratios: A Wireless Primer
- Speedlite 580EX II External Automatic Flash Exposure Sensor
Get your flash unit out, it is indeed fully integrated and automatic. Flash photography is no longer banal, in-your-face, hit-or-miss, or too complex to use; you will be surprised with the results.