Canon 1D Mark IV Flash

Canon EOS-1D Mark IV Flash

Like most pro cameras, the Canon 1D Mark IV has no internal pop-up flash, but provides both an external flash hot-shoe as well as an external PC socket (no polarity) for connecting a strobe. The hot-shoe accommodates all Canon EX series speedlights, as well as a variety of third-party flash units, as well as older Canon strobes. Third party and historic units may have restrictions in terms of compatible features compared to current EX-series models, however. For Canon's older strobes, these are summed up in the table below.

Compared to the 1D Mark III, the 1D Mark IV has a tweaked E-TTL II algorithm that better uses lens distance information to prevent inconsistent exposures, especially with dark subjects or backgrounds, or when shooting a small subject with a wide-angle lens.

The 1D Mark IV still allows external flash strobes to be disabled while still using their AF assist beam for easier low-light focusing without flash, but also adds the ability to disable AF assist for flash strobes such as the Speedlite 270EX, which lack an IR assist beam, and instead provide assist with repeated bursts of low-power flash. Note, though, that even among EX-series flash strobes, certain models may not be able to provide AF assist with certain assist points. Only the 580EX II, 580EX, 550EX, and ST-E2 are guaranteed to provide AF assist to all the 1D Mark IV's AF points.

A Flash Exposure Lock button allows users to lock the flash exposure in advance of the shot, and a Flash Exposure Compensation option adjusts the overall flash power from -3 to +3 EV in one-third-step increments (only for Canon EX series speedlights). Automatic flash exposure bracketing is also available, and the 1D Mark IV newly supports flash exposure microadjustment, allowing flash exposure strength to be fine-tuned within a +/-1 EV range in 1/8EV steps.

The Canon 1D Mark IV's maximum X-Sync speed is 1/300 second, and is automatically set within the range of 1/300 to 30 seconds by default. Custom Function I-15 allows this range to be restricted within limits of 1/300 to 1/60 second to prevent blur, or fixed to 1/300 to ensure maximum sharpness, but both options may lead to darkened backgrounds, and prevent use of High Speed Sync. The HSS option synchronizes the flash with all shutter speeds available on the Mark IV, from 1/8,000 to 30 seconds. (Note though, that a full-power flash almost invariably lasts longer than 1/8,000 second, so you won't see the full flash power when working with a shutter speed that fast.) When using a wireless capable Canon EX flash unit, you can also sync up wireless slave units for greater coverage, with no connecting wires, special codes, or anything. Full TTL flash metering is available even with multi-flash wireless setups.

Other flash related options available on the Canon 1D Mark IV include setting the supported flash modes (E-TTL II, Manual Flash, Multi Flash, etc.), evaluative or average flash metering, first- or second-curtain synchronization, and -- for the 580EX II, 430EX II and 270EX -- in-camera access to Custom Functions specific to the attached Speedlite model. For other strobes, only E-TTL II, flash exposure compensation, and flash firing can be controlled from the camera body.