Which aperture produces the sharpest image?

This article is intended for those photographers using a digital single lens reflex (DSLR) camera or a digital mirrorless camera.  So, whether you are a novice or a professional, you should benefit from the information I’m going to share with you.

I’m a baby boomer professional nature photographer and I grew up using 35 mm and medium format film cameras. I now shoot with a Nikon DSLR camera.  Throughout most of my professional career I shot most of my nature/landscape photos using the smallest aperture available depending on my lens. I was taught early on, through reading and listening to my mentor, that the smallest aperture would yield the sharpest resolution and the greatest depth of field.

Recently, while researching technical information regarding a specific digital zoom lens, I learned that my perception of which aperture would yield the highest image sharpness, was in fact flawed. To say that I was surprised is an understatement. Perhaps many of you reading this article already figured out that apertures of f16, f22 and smaller don’t produce the sharpest images. Or, if you’re like me, then you might find this information quite surprising.

For starters, I don’t consider myself a technical person, so I’m not going to bore you with technical details. However, I am going to refer you to someone who is considered technical and who has built his reputation on researching, reviewing, and providing technical information about cameras and lenses. His name is Ken Rockwell. I highly recommend that you read Ken’s article: “How to Select the Sharpest Aperture”.    https://www.kenrockwell.com/tech/focus.htm

The bottom line is that as a rule of thumb, the sharpest aperture will be 2-3 stops from wide open, which correlates to f8 on most lenses.  At most apertures, the center of the image is usually quite sharp, but depending on the aperture, sharpness at the edges falls off significantly at smaller apertures. So if you’re looking for sharpness at both the center and edges, then I would recommend shooting at f8, or at least no smaller than f11. From what I’ve read, there is a technical reason why sharpness is reduced at small apertures, which is the result of diffraction. Again, I’m not a technical person, so I highly recommend that you read Ken Rockell’s article.

Many of you might be wondering how to achieve image sharpness from the foreground through the background when shooting at f8. I guess it depends on what you’re shooting. When shooting photos of people, quite often you want the background out of focus. I’m a nature photographer and concentrate primarily on landscapes, so here is my recommendation. If you’re using a wide-angle prime lens or a wide angle zoom lens, then your depth of field is going to be quite good at f8. However, if your scene includes an object in the foreground you want in sharp focus, including the background in focus, then you might consider focusing on a point about 1/3 the way into the scene. I hope you enjoyed reading this article and invite you to read other articles I’ve written on a number of subjects, as found on my website: https://www.rbphotonh.com