TTG Plus > FAQs > More on FAQ #1506

Why does P5 put a 1-second limit on manually combined exposures instead of some longer period?

  • 1. Because the goal is capturing “a moment,” and “1 second” is the shortest universally used time limit

    “One moment” is one of the 9 characteristics that every TTG-qualified photograph must have, and neither common definition of “moment” would accommodate combining separate exposures that were taken with a generous amount of time between them.

    • “One second” is universal shorthand for “a moment” (“Just a sec”).

    • Different countries use different units for measuring distance and weight but every country in the world measures time in “seconds” (Day > Hour > Minute > Second).

  • 2. Because “one second” is the longest universal time unit that applies when people think of a “glimpse” of a scene

    (See #2401 on the “glimpse”)

    That is why, on both the page on photographing lightning and the page on photographing fireworks, TTG photographers are advised that they will less likely be challenged on the satode aspects of an exposure that lasted less than 1 second.

  • 3. Because anything longer than 1 second would be arbitrary

    . . . (e.g., 17 seconds, or 39 seconds) until reaching the next shortest “universally familiar time unit,” the minute.

    Allowing the combination of different exposures recorded over the span of a minute is unlikely to be judged by the public as a guarantee of trustworthy photographs.

  • 4. Because every TTG photograph — including those made by combining exposures — must look like a single-exposure, undoctored photograph.

    The longer the combined-exposure time window, the more likely that changes in the scene between exposures will produce a result that requires making changes that are not on TTG’s Allowable Changes list if the image is to look like a single-exposure, undoctored photograph.

  • 5. Because having “no time limit” would lead to questionable combinations of exposures even of “motionless” scenes

    When discussing any limit imposed by TTG, the test is always to push that limit to its most extreme and then to ask “Would viewers trust the TTG label if it was applied to that extreme example?”

    That test applies to the idea of setting no maximum time-window on combining exposures (“I returned to this national park a year later and the scene hadn't changed at all, so I combined an exposure I made last year with an exposure I took this year”).

    See also #1507

  • The bottom line

    Advanced photographers routinely combine exposures outside of a 1‑second window, but that procedure is always done to enhance “appearance,” not “trustworthiness”...

    . . . and the point of TTG is to tell viewers when the photographer chose to optimize trustworthiness over appearance.

    Almost all of the most-widely trusted photographs in the world are recorded in less than 1 second (typically 1/60th of a second or less).

    See also #1505.