FAQ 22 • Perspective Correction
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2201. What is perspective correction?
This term usually refers to rendering vertical lines in the scene as vertical in a photograph.
Anytime the recording surface inside the camera is not parallel to the subject, vertical and horizontal lines in the subject will not be rendered as exactly vertical or horizontal in the resulting photograph.
• For example, when the camera’s recording surface is pointed upward at a tall building, the vertical lines of the building are not vertical in the photograph (even though the horizontal lines may remain exactly horizontal).
• Similarly, when the camera's recording surface is pointed down the length of a long building, the horizontal lines of the building are not horizontal in the photograph (even though the vertical lines may remain exactly vertical).
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2202. What perspective depictions are allowed by TTG?
TTG photographers can make photographs from whatever perspective they choose.
If the chosen perspective is difficult to comprehend or potentially deceptive, in order to meet P8 the TTG photographer may have to use the TTG-IC label (and perhaps add more explanation beyond that).
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2203. What perspective depictions are disqualified by TTG?
Depicting any perspective other than what the camera lens rendered always disqualifies the resulting image from TTG.
This includes all methods and results of post-exposure perspective correction, including reshaping things in the photo so that it looks like the camera had been pointed somewhere other than where it actually had been pointed.
The only reason anything can ever be reshaped in a TTG photo is for correction of lens/camera anomalies, #4 of TTG’s Allowable Changes.
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2204. Why does TTG disqualify perspective-corrected photos in which things were reshaped so that it looks like the camera was pointed somewhere other than where it was?
Among other reasons, because the result misrepresents where the camera was pointed.
TTG is about what the camera lens saw, not what the photographer wishes the camera lens had seen.
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2205. What about when software-created perspective corrections are programmed into a digital camera before the photo is recorded?
The resulting photos are disqualified from TTG because the correction occurs after the light hits the sensor (i.e., post-exposure)—
— even though the camera makes the corrections before the review image is shown on the camera’s screen. (See also #4 here.)
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2206. How do TTG photographers make “perspective-corrected” photographs if they can’t reshape things after the light passes through the lens?
The same way perspective correction has been done since photography was invented:
by keeping the sensor/film plane parallel to the subject and using only a portion of the lens’ image circle.
This can be achieved
• by using a wide-angle lens and cropping out any undesired portion of the result; or
• with a shift [rise] “PC” lens; or
• with a view camera.
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2207. What if I correct the perspective in a photo by tilting the easel when making a print in the darkroom?
The resulting image would still be disqualified by the “no-reshaping” prohibition of P2.
When it comes to meeting the Trust Test, TTG makes no distinction between digital and darkroom tools.
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2208. Why wouldn’t people trust a TTG-like label that allowed post-exposure perspective correction?
Because a label that has no limits on reshaping things would mean that wildly untrustworthy photographs would be validated by that label.
Viewers wouldn't trust a label that validated wildly untrustworthy photos.
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2209. But couldn’t TTG make limited allowance for reshaping things to accomplish post-exposure “perspective correction”?
No, because any attempt at such a policy would involve a completely arbitrary limit on the allowable amount of correction.
Arbitrary limits are often ignored because they are arbitrary.
Anyone who wants to draw up such a policy is welcome to try
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2210. Aren’t most excellent photographs perspective corrected?
That depends how one defines “excellent.”
None of the most famous and widely trusted news photographs are perspective corrected, and most of the general public either doesn’t notice or doesn’t have a problem with it.
More excellent photos that are not perspective corrected
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2211. Why does the “toy city” look disqualify photos from TTG?
Because it wouldn’t meet the rinairs standard in P7.
Most respected news agencies do not use contratilt and contraswing in information-reportage photographs.