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Keystone effect
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Jul 6, 2019 06:38:06   #
Noctilucent
 
Photoshop has the Lens Correction Filter. Under the Filter menu. A few items down. Takes care of the keystone problem, but you could lose some edges off your image.

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Jul 6, 2019 06:48:25   #
Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)
 
billnikon wrote:
Many Nikon camera's have it in the edit menu.


Nikon cameras do not have a parallax correction in the menu. Though some offer some keystone correction. It's in the retouch menu and it's called Perspective Control.

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Jul 6, 2019 06:50:51   #
billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont
 
Gene51 wrote:
Nikon cameras do not have a parallax correction in the menu. Though some offer some keystone correction. It's in the retouch menu and it's called Perspective Control.


My bad, you are correct. But it does a good quick job at perspective control.

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Jul 6, 2019 07:07:10   #
BboH Loc: s of 2/21, Ellicott City, MD
 
Take a look at the DxO suite of programs - one is ViewPoint Correction

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Jul 6, 2019 07:07:32   #
BboH Loc: s of 2/21, Ellicott City, MD
 
Take a look at the DxO suite of programs - one is ViewPoint Correction

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Jul 6, 2019 07:11:58   #
jaymatt Loc: Alexandria, Indiana
 
You can do it in Lightroom with the manual lens adjustment tools.

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Jul 6, 2019 07:15:23   #
mjmgka
 
[quote=E.L..
Oh- Sometimes Keystone is a good thing. It gives dynamic lines to tall modern structures. Theses are not architecturally correct but they make for nice advertising shots and annual report covers. I hope this helps! [/quote]

What book is the excerpt from that is shown in the pictures?

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Jul 6, 2019 07:40:43   #
Jimmy T Loc: Virginia
 
E.L.. Shapiro wrote:
The best way to address KEYSTONE distortion is while shooting. This is a common problem in photographing tall architectural structures from the ground. It is especially notable when buildings seem misshapen, look that they are lean over, crooked or falling over or when parallel vertical or horizontal lines seem to converge at an unnatural perspective. Basically, a rectangular shaped structure takes on a trapezoidal appearance in the photograph. This effect is especially present when photographing structures at fairly close distances with a wide angle lens or short focal length setting on a zoom lens.

In commercial/architectural photography the traditional way of correcting this in the camera was the use of a view camera with an adjustable front standard or a medium format or digital camera with a tilt/shift perspective control lens. This enables to keeping the film or sensor plane parallel to the subject and moving the lens, usually upward or downward to accommodate the height of the structure. If you do quite a bit of this kind of work, it pays to invest in this kind of equipment. This would require the use of a tripod and of course, it somewhat time-consuming in setting up each shot.

For more casual shooting as a hobbyist, enthusiast or tourist when shooting quickly and handheld, the best approach is to use one of a few different strategies- all having to do with camera position, placement in relation to the subject.

You can simply keep the camera (sensor) parallel to the subject structure (no tilting of the camer upward or downward) which may result in too much ground or sky in your composition- this unneeded space can be cropped out in post-processing. Of course, you are gonna need the distance. If possible, you can try to use a normal or moderately wide focal length. Attached, is a page out of an old Kodak Professional Photoguide that explains some f this theory in detail along with diagrams. This applied to 35mm cameras when view cameras or P/C lenses are not used- it applies to current digital equipment.

Another method that I use is to find higher ground or access that will enable me to shoot from about halfway up the subject structure. Sometimes a hill or natural elevation will do the job. I have shot from rooftops or windows of nearby buildings. On commercial jobs, I have used a cherry picker, other elevation device or a simple stepladder. This method makes for fast easy handheld shooting, exact composition without fussing with view camera or P/C adjustments.

Sometimes, no matter what you do or where condition are especially difficult, some post-processing correction will be required. Most of the popular software such as Lightroom and PhotoShop have some perspective control adjustments. Since I address most of my perspective control in shooting, I use a simple app that I can access on my tablet and make the adjust right on site so I know I have everything under control before I leave the location. See a screenshot of the app- there are two simple arrows to indicate the direction of correction and the rest is totally visual- line up the vertical lines with the grid lines on the screen. As with any perspective control or image rotation in post-processing, you will lose a few pixels. You will also lose a few in cropping out excessive ground and sky but nothing too seriously impair the image quality if out have a good composition where the main subject is dominant in the image space.

I do quite a volume of exterior and interior work for advertising clients. The same principles apply to interior work. Sometimes I have to work quickly in homes or hotel rooms that are still occupied by the residents so I can't get into complex setups. In an average room with an 8-foot ceiling, I place cameras at 4 feet and crop afterward. In one of the shots posted here, I had to use a view camera because the shot was made for the flooring company and a low angle was needed to emphasize the floor and force more depth of field.

Sometimes when shooting from high places aircraft, you can get a different kinda keystoning. When you shoot downwards, especially with a wide angle focal lengths, you get foreshortening. This makes structures seem large at the top and tapered toward the bottom- so you apply some of the aforementioned methods in reverse. Wh shoot full-length portraits, make sure the camera is at the subject's waste level otherwise they will appear shorter than they are.

Oh- Sometimes Keystone is a good thing. It gives dynamic lines to tall modern structures. Theses are not architecturally correct but they make for nice advertising shots and annual report covers. I hope this helps!
The best way to address KEYSTONE distortion is whi... (show quote)


Great tutorial!
Smile,
Jimmy T Sends
Bravo Zulu

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Jul 6, 2019 07:42:02   #
sb Loc: Florida's East Coast
 
bleirer wrote:
You could shoot straight on with the sensor parallel to the face of the building, and skip the correction.


That can take a very large stepladder if shooting a 20-story building....

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Jul 6, 2019 07:47:39   #
jerryc41 Loc: Catskill Mts of NY
 
will47 wrote:
What is the Keystone effect?


It's a term from architecture. "A keystone (also known as capstone) is the wedge-shaped stone piece at the apex of a masonry arch, or the generally round one at the apex of a vault." It applies very well to pictures taken at an angle.

https://en.wikipedia.org/wiki/Keystone_(architecture)

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Jul 6, 2019 08:52:28   #
nekon Loc: Carterton, New Zealand
 
in photoshop you need to use the transform tool, where you are able to pull converging top corners, apart. why it gets called "keystoning " is beyond me, as keystoning is the opposite,coverging at the bottom, as taken from top of a tall building, looking down.

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Jul 6, 2019 08:57:05   #
Retina Loc: Near Charleston,SC
 
E.L.. Shapiro wrote:
The best way to address KEYSTONE distortion is while shooting. Thivvs is a common problem in photographing tall architectural structures from the ground. It is especially notable when buildings seem misshapen, look that they are lean over, crooked or falling over or when parallel vertical or horizontal lines seem to converge at an unnatural perspective. Basically, a rectangular shaped structure takes on a trapezoidal appearance in the photograph. This effect is especially present when photographing structures at fairly close distances with a wide angle lens or short focal length setting on a zoom lens.

In commercial/architectural photography the traditional way of correcting this in the camera was the use of a view camera with an adjustable front standard or a medium format or digital camera with a tilt/shift perspective control lens. This enables to keeping the film or sensor plane parallel to the subject and moving the lens, usually upward or downward to accommodate the height of the structure. If you do quite a bit of this kind of work, it pays to invest in this kind of equipment. This would require the use of a tripod and of course, it somewhat time-consuming in setting up each shot.

For more casual shooting as a hobbyist, enthusiast or tourist when shooting quickly and handheld, the best approach is to use one of a few different strategies- all having to do with camera position, placement in relation to the subject.

You can simply keep the camera (sensor) parallel to the subject structure (no tilting of the camer upward or downward) which may result in too much ground or sky in your composition- this unneeded space can be cropped out in post-processing. Of course, you are gonna need the distance. If possible, you can try to use a normal or moderately wide focal length. Attached, is a page out of an old Kodak Professional Photoguide that explains some f this theory in detail along with diagrams. This applied to 35mm cameras when view cameras or P/C lenses are not used- it applies to current digital equipment.

Another method that I use is to find higher ground or access that will enable me to shoot from about halfway up the subject structure. Sometimes a hill or natural elevation will do the job. I have shot from rooftops or windows of nearby buildings. On commercial jobs, I have used a cherry picker, other elevation device or a simple stepladder. This method makes for fast easy handheld shooting, exact composition without fussing with view camera or P/C adjustments.

Sometimes, no matter what you do or where condition are especially difficult, some post-processing correction will be required. Most of the popular software such as Lightroom and PhotoShop have some perspective control adjustments. Since I address most of my perspective control in shooting, I use a simple app that I can access on my tablet and make the adjust right on site so I know I have everything under control before I leave the location. See a screenshot of the app- there are two simple arrows to indicate the direction of correction and the rest is totally visual- line up the vertical lines with the grid lines on the screen. As with any perspective control or image rotation in post-processing, you will lose a few pixels. You will also lose a few in cropping out excessive ground and sky but nothing too seriously impair the image quality if out have a good composition where the main subject is dominant in the image space.

I do quite a volume of exterior and interior work for advertising clients. The same principles apply to interior work. Sometimes I have to work quickly in homes or hotel rooms that are still occupied by the residents so I can't get into complex setups. In an average room with an 8-foot ceiling, I place cameras at 4 feet and crop afterward. In one of the shots posted here, I had to use a view camera because the shot was made for the flooring company and a low angle was needed to emphasize the floor and force more depth of field.

Sometimes when shooting from high places aircraft, you can get a different kinda keystoning. When you shoot downwards, especially with a wide angle focal lengths, you get foreshortening. This makes structures seem large at the top and tapered toward the bottom- so you apply some of the aforementioned methods in reverse. Wh shoot full-length portraits, make sure the camera is at the subject's waste level otherwise they will appear shorter than they are.

Oh- Sometimes Keystone is a good thing. It gives dynamic lines to tall modern structures. Theses are not architecturally correct but they make for nice advertising shots and annual report covers. I hope this helps!
The best way to address KEYSTONE distortion is whi... (show quote)

Great reply, especially your fifth paragraph on perspective. This helps prevent too much variation in effective focal length and the resulting variation in apparent size of the subject from one end to the other. As you mentioned, sometimes this stretch effect works in your favor. At other times it looks too unnatural regardless of whether it is done at the exposure with a tilt and shift lens or in post. For interior and some exterior shots, it helps to just raise the camera until parallel lines are close to parallel in the viewfinder. This is one reason I like a tilting rear display for composing. Thank you for including all the examples.

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Jul 6, 2019 09:06:58   #
rayr
 
Or you could switch to an Olympus EM1 Markll that will adjust it in camera.

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Jul 6, 2019 09:08:15   #
Blair Shaw Jr Loc: Dunnellon,Florida
 
I have a similar & parallel question: Would a Tilt-Shift Lens correct any of the distortions that were mentioned in the posts from members above or would it add to the confusion?

Jimbo

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Jul 6, 2019 09:17:45   #
Longshadow Loc: Audubon, PA, United States
 
E.L.. Shapiro wrote:

...
...
This is gonna be like the protracted "argument" as to whether perspective is governed by focal length or distance. I hope not!


I like to think discussion.
Are you arguing?

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