How to Fix Lens Distortion
Lens
distortion is a common issue we photographers deal with on a daily
basis. It can be split into two groups – distortion by perspective and
distortion by optics. Be it one or the other, it often causes
unnatural-looking deformation of photos we take. As a result, we end up
searching for ways to address distortion issues in the field, or
afterwards in post-production. Usually lenses with longer focal lengths
produce less distorted results than wide-angle lenses. And as you might
already know, distortion is much more noticeable closer to the edges of
the frame than in the middle. If you shoot landscapes or cityscapes at
wider focal lengths and you have straight vertical elements near the
corners of the frame, distortion might significantly bend and skew those
elements, making them look very strange. There are several ways you can
address such problems, so let’s talk about those now.
When
working in the field, there are some techniques you can utilize to take
care of distortion, but they might not prove to be very effective. You
can change your position and shoot from a spot further away from your
subject with the same lens. Another way is to use a longer lens, which
should hopefully exhibit less distortion compared to a wide-angle lens.
Unfortunately, both ways will affect your composition and framing, which
might not always be desirable.
By taking a few steps back and
keeping the same lens on your camera, you will either reduce or take
care of distortion issues completely. On the negative side, more of the
environment will be included in the image. If you switch to a longer
lens, the relationship between the foreground and the background will
change and if you are forced to move back, it will also trigger a change in perspective. As a result, your photo might get a completely different look and feel to it than originally intended.
The
last way is to switch to a tilt-shift lens (PC-E lenses for Nikon
users). PC-E lenses have advanced optics, which reduce distortion on
edges, and you can shift and tilt them to some extent. Shifting helps
fix some of the perspective distortion depending on how much shift is
needed. The counterpart is they are extremely expensive and come in few
fixed focal lengths. Because of this, the majority of photographers
decide to correct distortion in software instead.
Any modern photo
editing software has at least one way of dealing with distortion. The
tricky part is, their usage might not always yield great results. Quite
recently I took a sunrise shot of Prague. The Prague`s Castle is placed
on the top left corner of the frame and clearly suffers from distortion,
as you can see from the picture bellow. The architectural monument
cannot be left distorted, because it just looks strange if it is left
that way.
There are a few ways to fix such a problem. Choosing the Lens
Corrections option under Photoshop`s filter drop-down menu is often the
first thing that comes to mind. The correction is pretty similar if you
use Lightroom or Adobe Camera RAW. By changing vertical transformation,
the walls of the Castle and the surrounding buildings will be
straightened. The process works well with little to moderate distortion
levels, however, quite a big portion of the image will get wasted during
this process and it gets worse when attempting to take care of heavy
distortion.
In the above case, a huge chunk of the foreground and the corners
with that morning`s golden light will have to go. So in this case it
might not be the best way to take care of this issue, as I want to keep
the foreground in the final image.
The second option is to use the
free transform tool. By moving the bottom left corner even more to the
left and out of the image, the left top corner will be straightened.
More of the image will be saved this method. Unfortunately, this method
also affected the hill on the right side and deformed it quite a bit by
stretching it.
To fix distortion, you will need to do a bit more work in Photoshop,
since these two “easy fixes” won’t do the job correctly. The first step
is to duplicate the layer you need to correct, which in my case is the
background. The second step is to straighten the newly created layer
using the free transform tool technique. To do it, just hold CTRL on
Windows or Command on Mac while clicking and dragging the left bottom
corner. This way the relationship between the foreground and the
background won’t change. If you do the correction with the Lens
Correction filter, the relationship and angle will change, making the
blend more difficult and in some cases, almost impossible. The third
step is to change the blending mode of the corrected layer to
“Difference”. This will make the photo look messy, but don’t worry, as
we’ll fix it in no time. The fourth step is to align the top layer with
the layer bellow based on the subject we corrected, which in our case is
the Prague Castle.
Try to get as much black color as possible. Black indicates that the
pixels match exactly. The brighter the pixels’ colors get, the further
away they are. There is no way to get it to match perfectly without
deforming the layer back (which would be counter-productive), so don’t
worry about it. After finding the best position, just apply a black
mask, which hides the corrected layer and set blending mode back to
“Normal”. The final step is to use a white brush to reveal the part that
you have just fixed. Some additional cloning and fixes might be
required. If so, execute them on a new blank layer.
Following the above steps, you can fix distortion on photos without
losing a big chunk of pixels and take your images to the next level. And
here is the final edit of the sunrise in Prague:
Hope this article usefull for you ...
Find more info here : https://photographylife.com/how-to-fix-lens-distortion
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