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The Nikon D800e and Diffraction

Sunday 17 June 2012

Simple put, diffraction is a loss in image quality at small apertures (ƒ16, ƒ22, etc) due to the bending of light around the inner edges of the aperture diaphragm in the lens. This bending of light makes fine details less sharp than they would be at, for example ƒ4, ƒ5.6 or ƒ8.

Diffraction has been with us since the first photographic lenses were designed, but typically it is not a problem for most people. The potential effects of diffraction are of considerable importance to me as a landscape photographer. My goal is to create photographs that people feel they can walk in to. This means I want to maintain maximum sharpness from the immediate foreground through to the far background and to achieve this I need to be using the smallest apertures.

As digital sensors gain higher and higher pixel counts, diffraction becomes more and more noticeable. Also, those who work at producing wide format fine prints with exceptional sharpness worry about the effects of diffraction. That being said, diffraction effects that can been seen at 100% on screen are not always visible in wide format prints and rarely are seen at normal viewing distances of those prints.

Given all the questions and discussion of diffraction with respect to the Nikon D800e, I thought I should post some samples from my first morning shoot with the new camera. These photos were made with a Nikkor 20mm ƒ2.8 AF-D lens with a lens hood but no filter. The camera was mounted on sturdy Manfrotto 055 legs with a more than adequate tripod head. Mirror lock-up was used along with an electronic release so that no vibration could be introduced to the camera. The samples presented here have minimal processing. They were exposed-to-the-right to take best advantage of “more signal and less noise” offered by higher exposures.

Here is the series of photographs shot from ƒ5.6 through to ƒ22. I am providing both the default sharpening and sharpened images for comparison.

  • At ƒ5.6, you will notice some foreground elements near the bottom slightly out of focus due to less depth-of-field. That seems to clear up by ƒ11, but then the effects of diffraction begin to take over.
  • As you look through the images, keep an eye on the snail as it progresses up the dead stem.
  • You be the judge as to whether diffraction can be reasonably “sharpened out”. Remember, these are screen captures at 100% – true pixel peeping with a 36.3MP sensor. Are the effects noticeable on fine prints? I doubt it, but will follow this post up with a a few prints.

Here is the gallery of images. You can click on the first image and scroll through them to view each one in turn. When you are “in” the gallery (darkened screen) you can right-click on an image and select “Open Image in New Window” or “Open Window in New Tab”. That will allow you to view the full-sized images in your browser. You can also right-click and choose “Save As…” or “Download” for viewing in another app.

So, you be the judge – is diffraction at small apertures a problem?

 

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