Today’s Question: With a subject that includes horizontal and vertical lines, such as a building, how important is it to get the final image to have lines that are perfectly horizontal and vertical, versus being a little askew due to perspective issues?
Tim’s Quick Answer: While accurate alignment in a photo can be important, I don’t think it is always necessary to completely correct perspective issues for all images. In some cases, having lines that are not aligned perfectly can actually add to the impact of a photo.
More Detail: One of my biggest pet peeves when it comes to evaluating a photo is seeing blemishes or other distractions in the photo. In some cases that distraction takes the form of improper alignment, such as when a horizon is crooked. A more extreme example of a lack of proper alignment is when straight lines within the image don’t appear straight, and perhaps aren’t perfectly horizontal or vertical.
However, in many cases a lack of proper alignment can actually be a good thing. For example, if you use a very wide fisheye lens that has perhaps an angle of view of around 180 degrees, straight lines within the scene are most certainly going to appear curved and distorted. But that distortion is a big part of what makes a photo captured with a fisheye lens so interesting and eye-catching.
I think the most important consideration when it comes to correcting for perspective and alignment issues in a photo is what looks right or most pleasing for an individual photo. I rarely correct an image so that all lines are perfectly horizontal or vertical, though in some cases I most certainly do.
To provide a very general guideline, if you have a photo where the key (or solitary) subject clearly stands out in the frame and looks like it should have perfect alignment, then it probably makes sense to ensure that all lines are perfectly horizontal or vertical.
For photos that have a relatively wide angle of view, and especially when the perspective effect makes the image more interesting, I might apply some slight corrections such as to ensure that the lines of a key subject in the center of the frame are perfectly vertical. But I most certainly won’t correct all images to remove all distortion or to ensure that all lines are perfectly horizontal or vertical.
Again, in my view the emphasis should be on what looks appropriate and pleasing for the individual image. If lines look like they should be perfectly horizontal or vertical, it is generally worth making sure they are aligned properly. But keep in mind that in many cases having lines that are somewhat askew or perhaps are slightly curved can very much enhance the look of an image.