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I took the following photo on on a recent holiday in southern Italy:

Original

I was pleased with the picture, but I could see that the horizon wasn't level, so I adjusted it (a simple rotation). The result was this:

Adjusted

Now, my horizon looks level, but my lighthouse isn't!

Note that there is some land very faintly visible in the left half of the photo (which would be Albania, I think), but I don't think that affects the horizon. The original photo with a horizontal line on it looks like this:

enter image description here

What's going on here!?? How do I make the photo look 'right'?


For those that are interested, the photo was taken here

  • 2
    It's hard to tell because of the haze in the distance, but it almost looks to me like there are mountains, etc above the water line at the horizon, in which case the "tilted" horizon might be an illusion due to the water-to-land interface being closer on the left side of the frame than the right, in which case your actual horizon is closer to being straight than it appears to be. – twalberg Oct 2 '18 at 14:59
  • @twalberg That did occur to me, hence the third image. Doesn’t look to be enough though, to me. – bornfromanegg Oct 2 '18 at 15:43
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    @twalberg That would be Albania on the horizon. – Stan Oct 2 '18 at 15:44
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    FWIW I prefer your original shot! – Lightness Races with Monica Oct 3 '18 at 18:11
  • @LightnessRacesinOrbit Thank you! That's good to know. As I've mentioned somewhere else, I've looked at both photos for too long now to really know what I think any more! – bornfromanegg Oct 4 '18 at 7:28
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Because you are shooting with the camera pointing down, you have convergent verticals. This can be fixed with the perspective tool in your image editor:

enter image description here

In theory, you should fix the perspective before you rotate the image to fix the tilt, but when you do it in that order, your have no good reference to fix the perspective, so straightening the horizon first will give a better (if less accurate) result.

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    "convergent verticals". It took me a paragraph to say that... =) – scottbb Oct 2 '18 at 17:12
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    Seems like, by symmetry, if the lighthouse had been in the center of the frame, it would be vertical. Is that correct? And if having the lighthouse to edge is desired, would taking a wider angle with the lighthouse in the center, then cropping out the right side work? – Acccumulation Oct 2 '18 at 18:09
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    @Acccumulation if the lighthouse had been in the center of the frame, it would be vertical. Correct. would taking a wider angle with the lighthouse in the center, then cropping out the right side work? Yes, but only to the extent that no other vertical lines are visible or are noticeable. For instance, the tapering conical shape of the lighthouse obscures the convergent verticals caused by the camera being aimed slightly downwards. If the sides of the structure at the base of the lighthouse were taller, you'd see them converge towards the center bottom, even if the lighthouse were centered – scottbb Oct 2 '18 at 18:19
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    @ Acccumulation if you had a wide angle, you would shoot with a horizontal lens (the horizon right in the middle of the frame), and then crop out the sky. – xenoid Oct 2 '18 at 19:22
  • "Seems like, by symmetry, if the lighthouse had been in the center of the frame, it would be vertical. Is that correct? And if having the lighthouse to edge is desired, would taking a wider angle with the lighthouse in the center, then cropping out the right side work?" That's pretty much how the shift part of a 'tilt/shift' lens works. – Michael C Oct 2 '18 at 22:23
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Ever notice when you try to take a photo of a building from the ground, when you aim up to get the entire building into frame, the building appears to taper towards the top? That happens because the camera is tilted vertically upwards.

When the camera is held level (in both the vertical and horizontal axes), all vertical and horizontal lines parallel to the plane of focus appear parallel. That is, they don't appear to converge (possibly somewhere outside the frame).

In your image, the camera is aimed slightly down, so vertical lines will converge at a point far below the image.

So, to get the horizon level and the lighthouse vertical (perpendicular to the ground) in the same image, you have to hold the camera level. The easiest way to do that, especially in this scene, is to aim the center of the camera at the horizon.

Unfortunately, that might not be the most desirable composition. Crop the result to suit your desired framing.


Note that this is exactly what perspective control lenses (also called tilt-shift lenses) do — rather than cropping in post, a PC lens aimed at the horizon, with an off-center shift "selects" the part of the scene in view, while keeping the perspective orthogonal.

  • Some object to the distortion caused after "correcting" perspective. You can't please all the people all of the time. – Stan Oct 2 '18 at 15:39
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    This makes a lot of sense, but I’m not sure how cropping is going to resolve it. I’ve already tried cropping around the lighthouse (i.e. the right side of the picture) but the horizon still looks at odds with the lighthouse. Am I missing something? – bornfromanegg Oct 2 '18 at 15:39
  • @bornfromanegg Scott was referring to a kind of lens that can "correct" for some optical effects caused by placing a three-dimensional image onto a flat image plane. They are referred to by different names as suggested in Scott's "note" in his answer. Cropping alone doesn't work as you've discovered. – Stan Oct 2 '18 at 15:52
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    @bornfromanegg You can't fix your existing image by cropping. My answer is about how to take an image that doesn't exhibit the problem in the first place. Step 1: take the image with a level camera. Step 2: crop to get the view. Alternately: Step 1: take the image with a level camera, with a PC lens, shifted to get the desired view. Step 2: there is no step 2. – scottbb Oct 2 '18 at 16:22
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    @Stan Certainly, there is some art involved in using PC lenses / techniques. Many photos with PC lenses actually have a small amount of upward aiming of the camera intentionally, to provide a very slight amount of building tapering. 100% straight buildings in photos usually look unnatural, as if they are actually leaning outwards (because the eye expects some amount inward leaning). Not all architectural photography, of course. There are several shots, especially of buildings like the flatiron building in NYC, that people shoot 100% orthogonal, to accentuate its form. – scottbb Oct 2 '18 at 16:24
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As others have noted, lines will converge or diverge depending on the angle at which you hold your camera. To fix this in images that have already been captured:

  • Use a perspective correction tool, as xenoid describes.

  • Use remapping software, such as Hugin, that can calculate an image-specific transformation. This is how lens-correction parameters are calculated.

At the scene, you can avoid the problem:

  • Keep the camera as level as possible and use a tilt-shift lenses, as scottbb describes.

  • Compose the scene so that important lines are centered. Lines closer to the center of the frame will appear to converge or diverge less than lines toward the edges. In your sample image, you would level the horizon and center the lighthouse. Zoom out so the entire area of interest is captured. Crop to the desired composition in post.

  • This is great to know. I do have a fondness for pictures which have the subject towards the edge of the frame, so understanding how this affects the image, and how to deal with it, is extremely useful. – bornfromanegg Oct 3 '18 at 9:39
3

In Lightroom you can use the Transform tool to correct horizontal and vertical lines. https://helpx.adobe.com/lightroom/help/guided-upright-perspective-correction.html

3

I don't know what the horizon looks like to the naked eye but what's the intent of the photo? As a pleasant landscape, to my eyes, the original looks best. The lighthouse appears vertical with its taper intact and the horizon dips as it would if you were looking down at a horizontal line vanishing behind the observer (sit in a chair near the center of a room and look down at the wall/floor intersection and up at the wall/ceiling intersection.) The cloud base appears approximately horizontal, diverging from the horizon, appearing closer on the left adding depth and motion, especially with the shoreline beneath.

The second photo rotates the right side (it's round, so there's only one side?) of the lighthouse tower vertical, making the entire photo seem tilted even though the horizon is level. The lighthouse wall taper is unnaturally enhanced by the left side appearing tilted to the right, the vertical shadow no longer vertical and the base leaning right. It still maintains well the illusion of depth.

The corrected photo is more orthogonal but emphasizes the foreground and loses quite a bit of depth in all three axes. The lighthouse appears to tilt left and the shoreline on the left appears closer or dropping right.

I once took a great photo of a grove of white birch trunks on the side of a steep golden sunlit grassy hill. With the exception of one tree, all of them were growing normally, straight up with the loner growing slightly to the right but almost perpendicular to the ground. Tilting my camera right so the loner was vertical and the ground approximately horizontal, the resulting image showed a grove of trees all growing tilted oddly left, the one now vertical tree setting the scene. Unless the loner was covered in the photo, it was almost impossible to "see" the artificial tilt that created the photo. Viewers focused on the one straight white tree trunk among the rest, not the slightly sloping ground line.

The same scene with the mass of trees shown growing as they really were was colorful but ordinary.

We tend to use vertical lines as references more often than horizontal lines. In your photo, the white lighthouse would likely be picked up first, then the horizon, then cloud base. If the lighthouse tower looks natural, the rest should follow. In a scene where horizontal elements dominate ( straight on street view of a house on level ground, e.g.) they are more important to have level.

  • 1
    We tend to use vertical lines as references more often than horizontal lines. In your photo, the white lighthouse would likely be picked up first, then the horizon, then cloud base. Is there a source you can cite that people generally use vertical lines as references? I'd love to read that. The reason I ask is that personally, I find non-level horizons to be very distracting, and less forgiving than converging verticals. – scottbb Oct 3 '18 at 13:11
  • Very interesting. I think I've looked at the photo for too long now to have an objective opinion :-), but I very much take your point. The original image appears more 'dynamic' in a way, to me, which I suppose is no bad thing. My concern is that the viewer would be distracted by the horizon, so your point about picking up the lighthouse first is great food for thought. – bornfromanegg Oct 4 '18 at 7:25
1

Sometimes it's easier to do in post with "PhotoShop" or other similar software.

At the location, I use the camera viewfinder frame edge itself as a reference edge by tilting down (or up) until the camera viewfinder frame is near the horizon.

Then, I level the head and lock it in one direction and tilt-up in the orthogonal direction to place the horizon in the best vertical position of "thirds" or whatever floats my boat, um or ship, for the exposure.

It's a quick two-step procedure.

  • Thanks for the response. I’m not sure what you mean though - you say “easier to do in post” but the process you describe seems to be something I should have done when taking the photo in the first place? – bornfromanegg Oct 2 '18 at 15:41
  • @bornfromanegg By "post" I was referring to using something such as PhotoShop after the fact. – Stan Oct 2 '18 at 15:48
  • So you’re describing a process I can perform in post then? “camera viewfinder” is something in Photoshop? – bornfromanegg Oct 2 '18 at 15:51
  • @bornfromanegg At the location, I use the camera viewfinder frame as a reference edge to align the horizon so that it appears horizontally in the original photo. I've found that a level horizon is preferable over other lens distortion effects. I think a tilted horizon will be noticed before the lighthouse will be seen out-of-plumb (vertical). We deal with distortions with our normal vision but the brain compensates. The brain will also accommodate this in photos too, to some degree. – Stan Oct 2 '18 at 15:59
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    I find that rows of autofocus points are better than the viewfinder edge for lining up horizontals: it means you don't have to move the camera as far to recompose, so there's less chance to rotate as you move. (My current camera has a built-in "spirit level" so I don't need to do any of that any more.) – David Richerby Oct 2 '18 at 17:41
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The horizon does not need to be straight, because you are not looking straight at the horizon. You're looking at the lighthouse, and the viewer's eye is drawn to the lighthouse, especially because of the angle of the horizon. Look at the edge of a table, it is straight when you look at it perpendicularly, but if you are looking at a corner it will be at an angle. The "corrected" version, where everything is orthogonal, does not draw your eye nearly as well to the lighthouse, it draws your eye to the center of the photo, which is not a very interesting place to look.

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