Diffraction, Sharpness and Nikon D800E
Wow Lloyd, your diffraction example of the trees at 5.6 and 11 is a mind blower. I had no idea I was doing this., though it was always bothering me that I couldn't get the detail I really thought possible. How do you get depth of field enough for landscape and still use apertures with little or no diffraction? I suppose focus stacking might be one solution.
DIGLLOYD: Probably the detail you are looking for is related to your choice of focus, as well as aperture. More on that below.
Remember, the Leica S2 has no anti-aliasing filter, and the Leica S lenses are second to none. Most lenses are not this good (lower contrast, more aberrations), and thus have less of an issue with diffraction, since they have other shortcomings that confuse the issue. And most digital sensors have an AA filter, further confusing the issue.
The Nikon D800E lacks an AA filter, which will make the issue more obvious for DSLR users, at least with top-grade lenses. I’ll be covering the D800E extensively, including lens performance and diffraction, especially in light of its much smaller photosites, which will make f/5.6 a limiting aperture for peak contrast, though I expect that f/8 will be perfectly acceptable, with f/11 becoming dubious with the best lenses.
Depth of field
DOF is a subjective concept based on resolution of the sampling device (sensor of film), the degree of enlargement (print size), etc.
Remember that the sensor is sampling the image with whatever resolution it has. Nothing is lost because the sensor now has 36 megapixels instead of 12 or 18 or 24 megapixels; in a narrow zone we get more detail by resolving to the sensor resolution, but the detail level drops off quickly outside that zone; the sensor outresolves what’s delivered to it. Stopping down to get a smaller COC (circle of confusion, e.g. more detail) is a tradeoff between reducing peak detail in a narrow zone, and increasing the detail outside that zone (circle of confusion vs diffraction spot size). The best tradeoff overall for full-frame DSLRs is typically at f/8, plus or minus one stop, depending on the sensor resolution and the subject matter. For the D800E, one might argue for f/5.6, but f/8 is probably better overall. Beyond that, loss of contrast will be readily evident with good lenses.
I optimize for a balance of the best sharpness and contrast for the most important subject matter in an image. With some experience, one will find satisfaction by choosing the focus point carefully for the intended visual impact (I never use the hyperfocal distance, a concept guaranteed to disappoint). Does the image below suffer from lack of depth of field? It is at f/2. It succeeds because of careful choice of focus.
- Blog chronological index for the past two months, which contain a great deal of discussion.
- Nikon D800 / D800E — Lens Requirements for 36 Megapixels
- Thoughts on D800/D800E Features
- Nikon 36 Megapixel D800 Without an Anti-Aliasing Filter?
- Moiré With the Nikon D3x and Moiré and How To Correct It.
Using f/2 for this commonly-seen bush in southern Death Valley makes for a clear separation of subject from background. There is no real need to have the hills and background sharp; it would add no useful context. What is the image about is the question each photographer must ask him/herself. In this case, this bush is seen throughout the park— I wanted to emphasize it as a individual specimen of its kind; the image is not about those mountains, though the mountains are important for context. Emphasizing the mountains by making them sharper would defeat my goal for the image, since it would de-emphasize the flowering bush.