DSLR photography is all about light and seeing how it affects the photos we take. As a beginner, we first understand how to adjust camera settings according to the available light only. This is achieved by varying any value of exposure triangle (Aperture, ISO or Shutter speed). But what if there is no light or less light? Or the user does not want to bump the ISO or decrease shutter exposure time? The first natural thought that comes to mind is adding light.
Light can be added in so many different ways, off camera flash is the most common technique. Addition of flash opens up a whole new world of learning opportunities which is the inspiration behind this beginner focused post. While getting started with DSLR flash photography, there are a few important topics that must be understood beforehand. We will discuss these in a list wise order one by one. 

1) AF assist beam: This is a red color focus beam light generated by the external flash unit to help the camera focus in dark situations. This prevents the camera from constantly hunting for something to lock focus on. Example: Nightclub photography. 

2) TTL (iTTL or eTTL): Stands for through the lens. TTL is like flash auto mode where the operator does not have to think about adjusting flash power when the situation changes. Read more details about when to use TTL mode in my previous post about TTL and manual flash photography.

Canon DSLR shot without flash

3) HSS: Stands for high-speed sync. Whenever the on-camera internal flash or external flash is used, shutter speed gets limited to a value of either 1/200 or 1/250 second. To overcome this limitation, most of the DSLR flash manufacturers make HSS compatible Flash Units. These units allow the camera shutter speed to go up to 1/4000 second. 

4) Flash Zoom: Just like lenses can zoom, flash units also have a capability to zoom into the area where the emitted light will go. Flash zoom defines how much area will be illuminated by the flash. Zoomed out flash will spread the light emitted to a wider area, zoomed in flash value will restrict it to a lesser area.

External or off camera DSLR flash

5) Triggering off-camera flash: Let's say there is a Speedlight or Speedlite mounted on a stand 3 feet away from the camera operator. How can the operator communicate to this flash about when to fire? This communication can be done in many ways.
Radio wireless triggers: Have attached a photo of my Yongnuo flash triggers as an example.
Infrared triggers.
PC sync cord.
Optical (Through inbuilt flash or another external flash on low power).

Off camera flash wireless triggers

6) Channels and groups: This is mainly for off-camera flash photography during events where multiple photographers are present.
Example: Photographer A has 2 flash units set up and Photographer B has set up 1 flash unit according to their choice. If photographer A is on channel 1 and photographer B is on channel 2, they will not trigger each other's flash units while taking photos. This is the main purpose of having channels. Under channels, there can be a single flash or groups of flash units. 

7) Optical master or Slave: As the name itself suggests, master flash is responsible for giving orders to other flash units about when to fire. Flash units following these orders are called slaves. The master sends pre-flashes which control the slave units. Not every flash unit supports dual master or slave mode.

That's all about flash photography beginners for now. If you found this post helpful, share the photography love by sharing this post. :)