TTG Brief #23: The satode test

“specific arrangement that occurred during exposure”

The satode test

{Summary: What to know}

This page explains why photographers cannot combine different people's facial expressions that were captured in different exposures.

1. What is “satode”?

As per P4, every TTG photograph — no matter how it was made — must depict only one “specific arrangement that occurred during exposure” (satode).
2. What is the purpose of satode?

Satode ensures that when combined or long exposures are used to photograph a subject that changes between the beginning and the end of the recording period...

. . . the resulting photograph does not depict an arrangement (“scene”) that the camera lens did not see.
3. When do photographers have to think about satode?

Only in two cases:

A. When combining different exposures of a scene that changed during the recording period (satode disqualifies the “Pick the best expression for each person from multiple exposures” feature available on smartphones)

B. When using long exposures to record a changing scene, especially scenes involving bright elements like fireworks (see #8 below).
4. What specifically does satode prevent?

The satode test prevents a photograph from depicting as simultaneous a combination of visual elements (that is, a scene) that never occurred simultaneously in real life—

—that is, the satode test prevents showing anything that was not a “specific arrangement that occurred during exposure.”

Every TTG-qualified photo depicts a specific arrangement of elements that would be seen in a momentary “glimpse” or “snapshot” of the subject.
5. Why is satode necessary?

Because photographing either of the two situations when satode is relevant — combined exposures and long exposures — can lead to misrepresenting what the camera saw.

It is impossible to put a precise directive on what can be extracted from combined exposures or a precise numerical limit on the length of long exposures.

Thus instead, to prevent misrepresentation, P4 reins in the effects of combined or long exposures.
6. What kinds of photos would not meet the satode test?

Example 1 (combined exposures): Smartphones make it increasingly easy to take a burst of photos of a group of people (or a couple), after which the photographer can combine into one photo the best expressions and poses from different exposures.

The resulting photograph depicts as simultaneous a combination of visual elements that never were seen simultaneously in real life.

Example 2 (long exposure): Advanced standalone cameras make it easy to hold the shutter open for an extended period during a nighttime fireworks display so that multiple fireworks bursts all across the frame that did not occur simultaneously are shown in a single photograph.

Again, the resulting photograph depicts as simultaneous a combination of visual elements that never occurred simultaneously in real life.
7. Are satode disqualifications easy to avoid?

Yes, they usually are.

Smartphone photographers who make no changes to a photo other than TTG’s Allowable Changes will rarely encounter any satode issues.

(Basically, “Turn off all effects, snap a normal photo, and leave it as is,” as it says in #3 of the Welcome FAQ. Obviously, using the “Pick the best expression for each person from multiple exposures” feature will always disqualify a photo from TTG, thanks to satode.)

Standalone camera photographers who like to manually set their exposures in dark settings can choose settings that prevent satode disqualifications.
8. What kind of subjects present the most “satode” challenges for standalone-camera users?

The most challenging scenes to photograph from a satode perspective are intermittent light sources (or bright items that are moving) in dark surroundings, for example:

• fireworks in the night sky

• lightning bolts

• a traffic light, a long exposure of which could show both red and green being illuminated

• a neon sign on which different parts are illuminated at different times

• a traditional theater marquee with hundreds of light bulbs that intermittently are on and off

• a Christmas tree on which the lights are not all illuminated simultaneously but each is illuminated at some point
9. Is TTG saying the things in #8 are hard to photograph?

No, with modern cameras it is actually very easy to photograph all of the bright subjects in #8 without running into satode issues...

. . . but it is hard to resist the temptation to use TTG-disqualifying [long] exposures to improve the appearance of the photo.
10. So how do TTG photographers deal with the “bright-changing-lights-in-the-dark” subjects listed in #8?

They have two main choices:

1. The photographer can make the exposure as long as they want and not worry about it qualifying as TTG.

Most viewers won’t be expecting to see the TTG label on something like a fireworks photo, which is why “fireworks” are on both this list and this list. (The most dramatic fireworks photos found online usually would not qualify as TTG, because they wouldn’t meet the satode test.)

2. The photographer can choose a shutter speed that is short enough to ensure that the photo does not depict an arrangement or combination of elements that never occurred during the exposure(s).

(Both the fireworks page and the lightning page suggest that single-exposure photos of 1 second or less are unlikely to be challenged on TTG/satode grounds; other subjects listed in #8 above may warrant other shutter speed choices.)