Pentax, Sigma, Promaster, Tumax T.5 Flash Duration

Pentax provides no duration information for the AF200FG, but for lists the T.5 time for both the AF360FGZ and the AF540FGZ as approximately ¹⁄₁₂₀₀ seconds at full power and ¹⁄₂₀,₀₀₀ seconds at minimum power. Unfortunately, Pentax customer service was unable to provide more detailed information on request. It's a bit odd that the same numbers are repeated for both flashes, since not only does full power vary greatly between them but also minimum power is ¹⁄₃₂ of full in one case and ¹⁄₆₄ in the other. We can estimate that the T.1 time is about ¹⁄₄₀₀ seconds at full power and that stopping-power goes as short as ¹⁄₆₀₀₀ with less-powerful flashes, but it doesn't seem safe to extrapolate too much from these numbers.

Sigma simply states that the flash duration for full-power firing is about ¹⁄₇₀₀ seconds. No details are provided, but it seems safe to assume that this is the standard T.5 measurement, which would put the T.1 speed at around ¹/₂₃₃ seconds — give or take. My request for more details was declined — "I spoke with our corporate office regarding this issue and unfortunately we cannot provide you with privileged information to you as it is not available at this time. We apologize for the inconvenience."

Promaster claims a duration range of ¹⁄₁₀₀₀ to ¹⁄₃₀,₀₀₀ seconds, and Tumax says ¹⁄₁₀₀₀ to ¹⁄₂₀,₀₀₀ seconds. Again it seems unwise to extrapolate much from this beyond the guess that this refers to T.5 time.

There are reports that the Tumax DPT3 series underexposes when a full charge is needed; this may be a symptom of a too-long flash duration at maximum power.

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