Almost all consumer level DSLRs and some of the pro level DSLRs come with the built-in flash. Professional photographers who shoot wedding, fashion, commercial portrait, or other special events do not rely on built-in flash to illuminate their subject. But, you don't have to use flash only when there is not sufficient natural light. It can also be used as a fill light to remove shadows or to add a catch light to the subject's eye. One of the best thing about the built-in flash is, you don't have to carry around an extra equipment and is always available on your camera, as long as the camera has sufficient battery power to charge and fire the flash. It can be put to use instantly whenever you want and doesn’t require any sophisticated setup. However, you need to understand few basics settings of your camera and should be comfortable navigating through the menu settings and the buttons on the camera.
Use of camera's built-in flash and its effect on the picture is determined by various settings on the camera, but most importantly, which metering mode you are currently using and what exposure mode you are on play a bigger role. Let's recap these camera metering modes briefly and then we can discuss about the steps we would be following in order to use on-camera flash. Since I wrote the blog about camera metering (in more detail) almost 9 years ago, Nikon has added a new metering mode; Highlight-Weighted Metering, which we will be discussing in the section below.
With the addition of Highlight-Weighted Metering mode, Nikon’s latest DSLRs use four types of metering modes and they are:
I. Matrix Metering
Nikon D810 uses 3D color matrix metering III with the type G, E, or D lenses and color matrix metering III, which doesn't include 3D distance information, with other types of CPU lenses. Matrix metering takes the entire frame into account and calculate the exposure based on tone distribution, color, composition, and distance information (with type G, E, or D lenses). Matrix metering mode produces a good result in most of the situations. It is also a default metering mode in most of the DSLR camera.
II. Center-Weighted Metering
In this mode, camera meters the entire frame but gives center area of the frame a greater priority while calculating the exposure. If you are using a CPU lens, you can set the diameter of the center area circle to 8, 12, 15, 20mm or to the average of the entire frame by navigating to b6, Center-Weighted area (on D810), in Custom Setting Menu. If you are using a non-CPU lens, the diameter of the circle area that gets the greatest weight for the metering would be 12mm, regardless of the setting selected for non-CPU lens data in the setup menu.
III. Spot Metering
Spot metering gives the priority to the small circle of 4mm in diameter (approx. 1.5% of the frame) centered on the current focus point and ignores everything in the frame. If you are using non-CPU lens or if auto-area AF is in effect, camera will meter the center focus point. This mode allows you to meter the exposure from off-centered subjects and ensures that subject will be correctly exposed no matter whether the background is much brighter or darker.
IV. Highlight-Weighted Metering
This is fairly a new metering mode and offered only in select Nikon DSLR cameras. In this metering mode, camera assigns the greatest weight to the highlights on the scene. This mode is designed to reduce the loss of details in the highlights. You can use this mode while photographing spotlit performers on a stage, or sunrise and sunset.
After a brief discussion of metering modes, let’s go through the steps to activate and use camera’s built-in flash.
Steps to follow while using the built-in flash
1. Select a metering mode
Matrix metering mode is the default metering mode in most of the cameras. If you want to change the metering mode, you can press the metering button (shown in the picture below) and rotate the main command dial until your desired mode is displayed in the viewfinder (or on the LCD screen near the shutter release button).
Nikon's flash utilizes the TTL (also called i-TTL) technology to determine the flash value. To learn more about the TTL and its types, please read - Understanding Nikon’s Flash Metering Mode. When you select matrix metering, or center-weighted metering, or highlight-weighted metering mode, camera activates i-TTL balanced fill-flash. And, if you select spot metering mode, camera automatically activates Standard i-TTL flash.
2. Pop-up the flash
After you select the desired metering mode, press the flash pop-up button to open the flash. When the flash is opened, camera starts charging the flash, and after the flash is fully charged, flash-ready indication will be displayed on the LCD screen, as shown in the picture below.
3. Select a flash mode
Press the flash button and while the button is still being pressed, rotate the main command dial (also known as rear command dial) to switch between various flash modes. Depending on which exposure modes you are on, supported flash mode will appear on the LCD screen as shown on the right side of the picture below.
Here is the list of various types of flash modes available in Nikon DSLRs.
Red-eye reduction with slow sync
Please refer to your camera manual to find out which flash mode is available in which exposure mode. To learn about these flash modes in detail, please read - Understanding Flash Sync Modes - Which Sync Mode Should You Use?
4. Take a picture
Compose the photograph, lock the focus by pressing the shutter release button half-way down or using the AF-ON button (this is when camera calculates the exposure settings) and then press the shutter release button all the way down to take a picture. When you press the shutter release button to take a picture, camera fires pre-flashes and gets the current lighting information Through-The-Lens (hence the name TTL) and passes that information to the flash metering system. Flash metering system then combines that information with the focal length and the exposure settings from the camera metering system, which shares the same metering sensor with the flash metering system. After analyzing and processing all those available information, flash metering system determines the final flash value to properly expose the subject and then camera fires the main flash. The timing of the flash firing depends on which flash mode you have selected in step 3.