Maybe you’ve visited a few photography forums and read posts from gearheads talking about finding sweet spots. And you’re probably thinking, oh lovely, more jargon.
This one might come in handy for you, though.
Lenses do not perform consistently across all possible settings. They’re usually at their worst at or near both ends of their focal lengths and apertures. Sharpness gets compromised. In addition, pictures you take also become subject to issues such as:
- Barrel and pincushion distortion
- Chromatic aberrations
The sweet spot is a particular setting, or range of settings, where a lens manifests these issues the least, if at all. This is where the lens can be at its best. The sweet spot differs with each lens and you can take a long time figuring it out for yourself. But lucky for us, whatever your lens is, chances are, somebody’s already figured out its sweet spot for us and very much willing to share his or her findings. All we need to do is search for that invaluable piece of information. For example, in an effort to learn how to get the best out of my Nikon 18-200 lens, I set out and did a Google search. That eventually led me to finding a diagram from the dpreview.com forum, indicating this lens is at its best at apertures between f/4 and f/8 with focal lengths from 18-75mm. I have made no thorough tests to prove or disprove this claim, but reviews of the lens do corroborate this to a certain degree.
Now, if you already know where the sweet spot(s) of your lens is, that does not mean you should stick with it all the time. What’s the point of owning this particular lens of mine if I tell myself it’s no good outside 48mm at f/8.0. I have a 50mm prime lens that would probably give me an even better image quality, anyway. There will be lots of times when I won’t hesitate to go both ends of the focal length at any aperture. Situations will call for them. I just need to know what to expect if I do.