The flash for many people is a mystery and can sometimes be aggravating. However, flash photography is a very necessary part of photography. The good news is that the flashes today are much more sophisticated and easier to use than ever. Simply by setting your flash to TTL (through the lens metering) will get you really close to where you want to be. Although many people think of using the flash first indoors, it is equally important to use out of doors. Flash will fill in shadows as well as make colors more true in both cases.
Here are some pointers for getting started with flash photography:
The Built in Flash Convenient because it is built into most DSLR’s. There is not much power in a built in flash and it will generally only go about 10-12 feet. Because it sits directly on top of the camera, the built in flash can be harsh unless it is diffused with a Promaster or similar “pop-up flash diffuser”. All built in flashes have an EV compensation available which will allow for modifying the output of the flash from +1.0 to -3.0.
The External Speedlight An external speedlight mounts onto the hot shoe of the camera. It is important to make sure it is in a locked position, because if the flash looses contact it will not fire and you can miss a shot. Although the external flash is heavier and bulkier, the physical size of the flash head allows it to produce more light and therefore travel further. The flash heads on these speedlights have the ability to bounce and swivel to allow for creative lighting effects. There are many diffusing accessories available to modify the light. More variable EV compensation, from +3.0 to -3.0 to modify the output of the flash.
Batteries Never store a flash with batteries in them, they can leak and cause a very costly repair. Keep plenty of charged batteries on hand as the there is no ‘battery indicator’ on the flash. I like rechargeable batteries because I just don't want to add more to the landfill if I don't have to, but they also recycle faster than alkaline. Use rechargeable batteries sold in pack of 8, this way you can have 4 in the flash when you are using it and 4 on the charger so you always have fresh batteries. I like to keep a pack of lithium in my bag for backup-they are more expensive but are the lightest weigh and recycle the fastest. I never use alkaline batteries because they seem to always leak in flashes and if left unnoticed can cause a very expensive repair.
Modify, Modify, Modify This is the best advice I can give to anyone that is planning on using a flash. The chief complaint about flash photography is that it is too harsh and creates shadows. Using some kind of flash modifying accessory is a simple way to get more pleasing results right away.
All flash light needs to be modified. Use a diffuser, many flashes come with them or buy one. Mini soft boxes are great, or larger soft boxes for even softer more direct light. Bounce cards, many are built in but there are also many to choose from that will give greater control over the quality of the light.