f/3.5
f/5.6
f/8
f/11
You have probably heard the term before. “The lens’ sweet spot is…” Almost every lens has one. The sweet spot is the aperture setting
or range of aperture settings at which your images are sharpest. For most lenses, it is somewhere in the
middle range of aperture settings for a given lens.
For example, with my Nikon 105mm f/2.8 macro, the sweet spot
for me is from f/8 to f/11. Now I
do love the wonderful soft focus that f/2.8 gives, but my images are not their
sharpest at this aperture setting.
As I go above f/11, once again the image quality is not to my liking. This is not to say that I cannot get
perfectly fine images at other aperture settings, and I very often use other
settings for a particular effect, but there is a certain change in the sharpness
as I move away from the f/8 - f/11 range.
So, how do you find the sweet spot of your lens? It’s really quite simple.
First, choose your lens (in my example here, I am using my
Nikon 105mm, f/2.8), and mount your camera on a tripod, or place it on a steady
surface to minimize camera shake.
If you do not edit in a program that will reveal your EXIF
data (aperture setting, shutter speed, ISO, etc), then be sure to have a piece
of paper handy to write down your aperture setting for each shot.
Set your camera on Aperture Priority (this allows you to
choose the aperture, and your camera will choose the required shutter speed),
and open the aperture as wide as possible for your particular lens. If you are not sure what your widest
setting is, you can usually find it right on the lens. I started with mine at f/3.5. Its widest is f/2.8, but I wanted to
minimize the number of photo you need to look at here. Now go ahead and take your shot.
Without moving the camera or recomposing your subject, close
the aperture a bit, and take another shot. Continue in this way closing down a bit with each successive
shot (f/5.6, f/8, f/11, etc.). Go
as far as you would like. For the
lenses I have, I usually don’t go much beyond f/16, but I encourage you to go
beyond that if you can, to see the results.
Now all you have left to do is review your images. Although not absolutely necessary, if
you can view your images at 100% resolution, it will be easier for you to note
the changes. You should be able to
see at which settings your lens is sharpest, and at which settings this
sharpness seems to change. Once
you’ve determined these settings, you’ve found the sweet spot for your
particular lens!
Notes:
The Iens I reference here is a prime lens (having one focal
length). If you are using a zoom,
you will need to set it to one focal length and leave it there as you increase
or decrease your aperture settings.
Once you find the sweet spot for a particular focal length, it will
usually be for that focal length only.
To find the sweet spot for other focal lengths just repeat the process
using your choice of focal length.
To keep from showing a long series of photos here, I have
posted only four, which I felt was the minimum number to give you the basic
idea.
