Perspective correction?

[Darryl Roberts]

Hi,

I plan on shooting this with my 5x7 Norma and a lens with plenty of space for movements. The building and the white tower would need to lean in opposite directions, is this possible?

Thank you

 

[AgX]

Perspective distorsion can be as well corrected and induced by swinging/tilting of the focal plane (camera back) against the object plane. These are the only movements necessary.

 

[Vaughn]

If you have enough image circle, keep the camera level and the standards straight -- use front rise to frame the image you want. This will make the verticals vertical. Then tilt the back forward to separate the buildings.

 

[Donald Qualls]

You want the verticals to diverge instead of converge? Tilt the back forward just a little, then use front rise to frame and front tilt/swing to place the plane of focus to keep both structures sharp. If you've got "plenty of movements" the biggest difficulty with the setup is likely to be ensuring that everything that needs to be sharp, is.

 

[Bob S]

If your camera has enough rise/fall on both the front and rear standards then it is easier to set the camera plumb to the buildings and use front rise and rear fall to capture the buildings and then use just a bit of front tilt.

 

[Darryl Roberts]

Wow. Again thank you all.

 

[Vaughn]

Watching the image change shape on the ground glass is a lot of fun. Playing with the perspective can be interesting -- sometime having the sides of the buildings perfectly parallel can seem odd if the viewer knows s/he is looking upwards. It can create the illusion that the building is actually getting wider as it goes up.

Enjoy!

 

[Darryl Roberts]

Watching the image change shape on the ground glass is a lot of fun. Playing with the perspective can be interesting -- sometime having the sides of the buildings perfectly parallel can seem odd if the viewer knows s/he is looking upwards. It can create the illusion that the building is actually getting wider as it goes up.

Enjoy!

Yup. Thank you

 

[Bob S]

If you have eliminated all keystoning you can end up perceiving that the building is leaning toward the camera.

 

[138S]

The building and the white tower would need to lean in opposite directions, is this possible?

Of course, this is a situation where view cameras shine. Usually you correct converging verticals with a front rise (or a rear fall) or with a base tilt, or with a combination of both, but in the sample you show the thing is more complex...

You also have distortion in the other axis, you first have to adjust shift/swing until your vanishing point is in the centered vertical, then you play with with rise or base tilt to correct the vertical convergence. (or first solve the vertical and later the horizontal...)

So in your case you have to correct both the horizontal and vertical convergence, just play with photoshop to see the effect, what you do with the camera movements will be equivalent, but that insane correction will deliver a not natural pictorial result:



When you have all lines vertical then you have that, see that to have all lines vertical you need to operate in the two axis, but you have to learn how to use those resources to enhance the pictorial result.

The tower at the right looks a bit curved, but this is because of lens distortion in your shot (not because of perspective distortion), so before correcting verticals lens distortion had to be corrected in PS.



Be totally proficient with camera movements and you'll get a lot of fun !!!

Please see this:



And:

https://en.wikipedia.org/wiki/Perspective_control
https://en.wikipedia.org/wiki/View_camera
https://en.wikipedia.org/wiki/Scheimpflug_principle

Also you may download The Camera by Ansel Adams , read from page 141

https://kupdf.net/queue/the-camera-...eue_id=-1&x=1594974965&z=OTMuMTc2LjE1Ni4xODE=

This is a "must have" book, it can be purchsed for some $15.

 

[Donald Qualls]

I strongly recommend The Camera -- I read it the first time at age 10, call it 1970. Every time I read it after that, I understood more of what he was saying.

I've got a Graphic View that I've used twice, probably a total of fifteen actual images (one pack of Polaroid in downtown Winston-Salem and a few sheets at a waterfall in the Smokies). I need to get out there and make some images -- my 150mm Componon should give enough coverage to exercise the movements a bit.

I have used front rise on plate cameras (doesn't work well, the lenses usually don't have any coverage to spare) and on my Speed Graphic a couple times. A single movement like this is actually even practical with a hand held camera (hint: the wire frame finder on most press cameras automatically compensates your framing for rise and shift).

 

[Bob S]

But this only illustrates camera movements with cameras with base movements. Some cameras have optical axis movements front and back, some have optical axis in front and base Tilts in back, some have asymmetrical movements front and back. Some have assymettical in back and base or optical axis in fron. Some are fixed axis assymetrical and some are continuously variable assymetrical axis.
Then some are yaw free and most are yaw prone.

so a lesson like you posted is most useful if the viewer has a camera with the same type of movements and features as the camera illustrated!

 

[138S]

so a lesson like you posted is most useful if the viewer has a camera with the same type of movements and features as the camera illustrated!

Hello Bob, I'd say that something it's important when learnig movements, this is to realize that the same effective movement can be played in several ways, for example a front tilt it's the same than some rear tith with a rise or fall in the front or in the back.

Or we do the same with different movements available in different cameras. In particular a rear base tilt it's the same than an on-axis tilt plus some fall and some extension, to place the GG in the same position than the base tilt did, similarly we also esily emulate a on-axis tilt after a base tilt.

Of course a luxurious Kardan has: "Freely adjustable, asymmetrical "floating" tilt axis on the rear standard... .... the tilt on the rear standard can be moved to any position within the groundglass area." I was llowed to play with a Kardan a friend has...