My recent love for doing DSLR Photography using external Flash has made me do a lot of experiments in past 2 weeks. In this post, I am going to talk about the two important working modes of an external DSLR flash unit. This post will summarize the working of each mode of operation and which one to prefer based on your subject, lighting, etc. The mode of operation of an external flash photography is classified into two main types:
TTL: Through the lens. Canon DSLR models have E-TTL whereas Nikon ones have i-TTL for the same mode.
When to use: Indoor photography with rapidly changing lights, fast movement, changing angles, distance variation from the subject, etc. are some major factors where e-TTL comes to rescue. It is not convenient to adjust the flash power every time in order to take a shot just because lighting changed. What would happen? The shot that you wanted to take might be gone by the time power is adjusted. If you are going to change aperture or shutter speed as well, try to stick with TTL. I usually like to keep TTL flash on my camera hot-shoe.
Bad side: TTL uses 2 flashes, one for metering and another one for the actual shot. This makes it really heavy on power consumption. Be sure to carry an extra pack of batteries.
|Foreground exposed using high sped sync TTL flash|
Manual: Like the word itself says, this mode involves setting the power manually.
When to use: Outdoor portraits, studio portraits, off-camera flash. This mode of external flash operation works really well when a user has full control over the subject and lighting. Example: Portrait photography.
Bad side: For me, the only inconvenient thing was multiple physical movements required to adjust power. Not an issue anymore, there are cheap third party remotes easily available these days.
1) Variation of f-stop in DSLR photography controls flash exposure, whereas shutter speed controls ambient light.
2) The manual changing of flash power and zoom level can be done by using optical or radio-based triggering.
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