Circles of Confusion and the Sweet Spot — Part 2

Author:  Sara Goodnick

Every lens has an aperture setting where it performs at its best. It usually isn’t constant all the way through the various apertures. Most often, you will find that at the widest and the smallest ends of the aperture spectrum, there will be some softness in your images.

In some cases, lens softness will still be acceptable, and it others it will not.

The only way to find out a lens’ limitations is to put it on a camera, put them both on a tripod, attach a shutter release, or set the shutter’s self timer, set the camera into aperture priority mode, manual focus on one spot somewhere and keep it there, then run through all of the apertures.

Afterwards, download them into your computer and examine and compare them. The differences may be subtle, but they will be there.

Here are my results for a few of the lenses I tested:

On my Nikon D700:

  • Nikkor  2.8 fixed, 70-200mm, best at f/8 and 11
  • Nikkor  2.8 fixed, 35-70mm, best at f/5.6 and 8

Lumix GX8:

  • Panasonic, variable 3.5-5.6, 14-42mm, best at f/11
  • Panasonic, fixed 2.8, 35-100mm, best at f/5.6
  • Panasonic, variable 4.0-5.6, 100-300mm, best at f/4.0 and 5.6

The images below are from the Lumix GX8:

Sara Goodnick is a trip leader with Arizona Highways Photo Workshops

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