A preflash is fired and the resulting readings compared to the ambient light reading for each of the camera's 35 metering zones from just prior to the flash, to identify and compensate for specular objects (that is, very reflective surfaces).
(As mentioned above though, note that the ST-E2 wireless sync transmitter can also be used for AF assist during non-flash photography, a handy trick.)Ĭanon's E-TTL II flash exposure system also works with certain lenses to include object distance data into its calculations so it can adjust the flash power accordingly. For example, the AF assist beam on the 550EX is rated as good to about 50 feet, versus the roughly 13 feet of the pulse flash on the Canon Rebel XTi itself. (This is the maximum shutter speed that can be used on the Rebel XTi when working with a non-dedicated, FP-capable speedlight.) When used with higher-powered studio strobe systems, Canon recommends a maximum shutter speed of 1/60-second or slower, to accommodate the time/intensity profile of such units.Ī final benefit of the dedicated Canon speedlights is that they carry powerful autofocus assist illuminators that can extend the range of the built-in AF assist light of the Rebel XTi. VERY handy, and likely to save lots of shoot/check/reshoot time!Īs alluded to above, the "X-sync" speed of the Canon Rebel XTi is 1/200-second. This creates the illusion of a constant light source for your eyes, letting you preview the lighting on your subject when the flash fires. With a F550EX or F580EX connected to the XTi, pressing the camera's Depth of Field Preview button causes the speedlight to fire at 70 flashes per second for about one second. The "Flash Modeling" feature of the 550EX and 580EX speedlights is quite useful. Canon's Speedlight system permits TTL flash metering with multiple remote units, and even allows you to set differential power ratios between the slaved units, over a six-stop flash exposure range. You'll note the references to "E-TTL remote" capabilities in the table above.
Canon ip3000 12 orange blinks manual#
Manual operation only, connect via threaded PC sync socket on camera body Here's the rundown on Canon Speedlights and their compatibility with the XTi: Speedlight Model (FP sync mode is referred to as "high speed" mode on the Canon 550 and 580 flash units.) This can be invaluable when you want to exclude ambient light from the exposure. Uniform, long-duration flash pulses like this permit use of shutter speeds as high as the 1/4,000-second maximum that the Canon Rebel XTi is capable of. On the Canon Rebel XTi, this requires a flash duration of 1/200-second. FP sync requires a flash unit to provide uniform light output for a relatively long period of time, long enough for the focal plane shutter curtain to fully traverse the sensor plane. Among these are true FP (focal plane) flash sync, flash exposure bracketing with external flash units, flash modeling, and E-TTL II exposure control. Several of the more impressive features of the Canon flash system depend on the dedicated 550EX or 580EX speedlight. A Flash Exposure Compensation feature controls the flash exposure +/- 2 stops in 1/2 or 1/3-stop increments. This struck me as very handy, akin to the more conventional autoexposure lock function for handling difficult ambient lighting conditions. E-TTL II is only available with the built-in flash or when the camera is paired with either the 550EX or the new 580EX flash.Īnother nice touch is the Flash Exposure Lock button, which fires the flash under manual control before the actual exposure, to determine the proper exposure setting. Custom Function 08 turns this mode off and returns to an average metering system. The Rebel XTi also uses E-TTL II control for both the built-in and compatible external flashes (according to Canon this includes the older 550EX flash, as well as the newer 580EX though the 580EX offers even more), a new standard that promises, and seems to deliver better, more balanced exposures. This makes it very easy to balance flash and ambient lighting for more natural-looking pictures. (Reasonably powerful, but not dramatically so.) The Canon Rebel XTi gives you a great deal of control over flash exposure, allowing you to adjust flash and ambient exposure independently of each other, in one-half or one-third EV increments.
Canon ip3000 12 orange blinks iso#
The Rebel XTi's built-in flash has a guide number rating of 43 feet (13 meters) at ISO 100, translating to a range of about 15 feet at ISO 100 with an f/2.8 lens.