TTG Guide #7: Focus and bokeh blur

A guide to

Focus and Bokeh Blur

1. TTG photographers can use whatever lens* and aperture they want when recording a scene.

Photographs that exhibit any amount of optically [lens] generated bokeh blur are eligible for TTG.

That principle applies whether the image is shot “wide-open” with a large-aperture lens on a large-sensor camera or “stopped down” with a small-sensor camera (or any combination in between).

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*If using a swing/tilt setup of any kind — whether a precision tilt/shift lens, an aftermarket tilt adapter, a Lensbaby, or a view camera — see #7 below.
2. A photograph is disqualified from TTG if it does not show as much of the scene as “in focus” as can be, based on the sum of what the camera recorded in all of the components that comprise the photograph.

(The focus maximization requirement is in P3.)

#2 applies regardless of the device used to make the photos and regardless of how many exposures were combined to make the photo.
3. Any non-optically generated bokeh blur added to the photo — including bokeh blur added instantly by smartphones in “Portrait” mode — must be undone or the photo will be disqualified from P2 and thus from TTG.

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What exactly is meant by the term “bokeh”?

Smartphones are increasingly adept at simulating — through “bokeh blur” — how a lens records out-of-focus backgrounds.

But “simulations” aren’t trustworthy enough to qualify as TTG photographs (see the brief on “seen vs. simulated”).

Apart from TTG’s Allowable Changes, all non-“light”-related aspects in TTG photographs must be left as they were recorded — not as anyone wishes they had been recorded.

Fortunately for TTG photographers, on smartphones it is easy to Undo any added focus blur and have the photograph depict all areas of the photo as much “in focus” as they were recorded (see #2 above), without any added simulations.

To Undo “bokeh” blur on a smartphone, the slider controlling the amount of blur is simply slid to the setting that depicts the least amount of blur.

{{{{Fortunately, that added bokeh blur can usually be undone very easily should the photographer want the image to be eligible for TTG.

• The amount of blur that the smartphone adds to the photograph is usually adjusted by a slider.

• Moving the slider all the way in one direction will reveal as much of the scene in focus as the camera has stored without adding blur.

• That focus maximized version of the photo is eligible to qualify as TTG.

Questions #1210–1214 deal with bokeh blur

See also #2 in the guide to focus and bokeh blur.}}}

FAQ questions #1210-1214 deal with “bokeh” blur.

What is “fauxkeh”?

See also “Why isn’t my favorite manipulation allowed?”
4. Photos are disqualified from TTG if the “quality” of out-of-focus areas is changed.

It isn’t just about how much (“quantity”) of the scene is rendered out of focus:

Any post-exposure changes of any kind* to bokeh, blur, or the rendering of out-of-focus areas disqualify the photograph from P2 and from TTG.

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*apart from effects of TTG’s Allowable Changes
5. Something in every TTG photo must be in focus.

A photo with nothing in focus will not meet rinairs (as required by P7) and is TTG-ineligible.
6. Focus stacking of a motionless subject is allowed in principle...

. . . but on a real-world level it would be difficult or impossible — except on a very limited and automated level — to refocus quickly enough to start all of the exposures within the same single second, as required by P5.

See the guide to combining exposures for a complete list of the “combining” limits imposed by the Trust Test.
7. Contraswing and contratilt effects (the “toy city” look) — always disqualify a photograph from TTG.

“Contraswing” and “contratilt” effects are the rendering of prominent areas of the photograph less in focus by making the camera’s “focus” plane non-parallel with the “recording” plane.

Contraswing and contratilt effects can be achieved at the time the photograph is recorded (with use of a geared tilt lens, with a view camera, or with a Lensbaby or similar flexible lens) or they can be achieved later, with software.

Since contraswing/contratilt images cannot meet rinairs (as per P7) no matter how many of TTG’s Allowable Changes are applied, those images are considered TTG-ineligible.

Contraswing/contratilt images cannot qualify for the TTG label no matter how they are achieved, presented, labeled, or explained.

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Note that using “swing” or “tilt” during the exposure to render prominent areas of the photograph more in focus does not disqualify photographs from rinairs or from TTG. See the Key for more, and see this page.
8. When multiple exposures are combined, all focus effects in the final image must be “optically plausible” or the photograph cannot meet P7.

“Optically plausible”

Guide to combining photographs

P7 of the Trust Test

1. TTG photographers can use whatever lens* and aperture they want when recording a scene.

2. A photograph is disqualified from TTG if it does not show as much of the scene as “in focus” as can be, based on the sum of what the camera recorded in all of the components that comprise the photograph.

3. Any non-optically generated bokeh blur added to the photo — including bokeh blur added instantly by smartphones in “Portrait” mode — must be undone or the photo will be disqualified from P2 and thus from TTG.

4. Photos are disqualified from TTG if the “quality” of out-of-focus areas is changed.

5. Something in every TTG photo must be in focus.

6. Focus stacking of a motionless subject is allowed in principle...

7. Contraswing and contratilt effects (the “toy city” look) — always disqualify a photograph from TTG.

8. When multiple exposures are combined, all focus effects in the final image must be “optically plausible” or the photograph cannot meet P7.