When one straightens two (vertical or horizontal) lines the other lines often are not straighten

Focal plane is parallel to the sensor plane. The distance between them is the perpendicular distance between them. When I focus on a wall with the camera all the wall is in focus. So it is with this building when using a levelled camera. I just wonder if I also get that strange ‘feeling’ as with the corrected image.

I assume raised is shifted. I think the trick with this is using the possibilities of an oversized image circle of the lens.
But I don’t have that strange feeling as with this corrected image.


Indeed - shifted upwards.

Of course. The image of Bourges cathedral was taken with a Schneider-Kreuznach 72mm f/5.6 Super-Angulon, which has an image circle of 229mm, which allows a maximum shift of 44mm.

That’s because the example image is quite an extreme wide angle

That are know figures? I never used a tilt/shift lens so I’ve no idea.

That still doesn’t explain it.
Just a guess. One can straighten the image but the direction of the camera is still there: the middle of the image when no cropping was used. My brain says the top of the building, which is further away, must have a smaller magnification as the bottom, which is closer. By leveling this is undone. Maybe my brains can’t deal with that and just says: it’s further away so it must be bigger.
Just a thought. That’s why I would like to see an image taken with a leveled camera.


I have just shown you two.

Right – and if it is not as ‘expected’, but all leveled (all vertical lines parallel…), it may look wider at the top because of your assumption.
A way to handle this is to let the vertical lines slightly converge until your perception tells you “right”.


Post 40 :wink:


I first aligned the right side with the middle using the Force Parallel tool then exported as a TIFF. Then I used the FP tool on the new file to align the left side with the other two. The “wider at the top” and “left side leaning in” illusions are still present but all three lines are now vertical.