Why f/16 is *Often* Suggested (and why it's problematic):
* Maximizing Depth of Field (DOF): f/16 is a smaller aperture, which generally leads to a greater depth of field. This means more of the scene, from near to far, will appear acceptably sharp. This is the main reason it's often recommended. The goal is to keep everything from the foreground to the distant mountains in focus.
* Sharpness Myth (and Diffraction): There's a persistent misconception that stopping down *always* leads to sharper images. While closing down the aperture can sometimes improve sharpness by correcting for lens aberrations, going too far can actually *reduce* sharpness due to diffraction. Diffraction occurs when light waves bend around the edges of the aperture blades, causing a softening effect.
Why f/16 is *NOT* Always Best:
* Diffraction: As mentioned, diffraction becomes a significant problem at smaller apertures like f/16, especially on modern high-resolution sensors. The resulting image may appear softer overall than one shot at a slightly wider aperture. The "sweet spot" for sharpness on most lenses is often between f/5.6 and f/11.
* Image Sensor Size: The effect of diffraction is more pronounced on smaller sensors (like those in smartphones or crop-sensor cameras). Apertures that work well on a full-frame camera might cause significant diffraction on a crop sensor.
* Exposure Time: Using f/16 necessitates a longer exposure time to achieve proper brightness. This increases the risk of:
* Motion Blur: From camera shake (requiring a tripod) or moving subjects (like water or leaves).
* Overexposure in Bright Light: Even with a low ISO and the lowest possible shutter speed, you might overexpose the image in bright sunlight. In these situations, you might need to use an ND filter (Neutral Density filter) to reduce the amount of light entering the lens.
* Dust Spots: Smaller apertures make dust spots on your sensor more visible in your images.
* Not Always Necessary: You might not *need* that much depth of field. If you're focusing on a subject relatively far away, a wider aperture like f/8 or even f/5.6 might provide enough depth of field while giving you a sharper image and a faster shutter speed.
So, What's the Right Approach?
The "best" aperture for landscape photography depends on a variety of factors:
1. Desired Depth of Field: How much of the scene do you need to be in focus? Consider what's most important to your composition.
2. Lens Performance: Know your lens's sweet spot for sharpness. Experiment to find the aperture where it performs best, balancing sharpness with depth of field. Most reviews will include sharpness tests at different apertures.
3. Sensor Size: Be aware that smaller sensors are more prone to diffraction at smaller apertures.
4. Lighting Conditions: Bright light may force you to use a smaller aperture and/or an ND filter. Low light might require a wider aperture and/or a higher ISO (which introduces noise).
5. Tripod Use: Longer exposures require a tripod for sharp images.
6. Focusing Technique: Proper focusing is crucial. Consider using focus stacking if you need extreme depth of field and want to avoid diffraction.
Alternatives and Considerations:
* Focus Stacking: Take multiple shots at different focus points and combine them in post-processing. This allows you to achieve a very wide depth of field while maintaining sharpness.
* Hyperfocal Distance: Learn about hyperfocal distance and how to calculate it. This can help you maximize depth of field with a specific aperture. However, hyperfocal distance calculators often overestimate the distance for modern high-resolution cameras, leading to soft results. Test and see what works best for you!
* Aperture Priority Mode (Av or A): Let the camera choose the shutter speed based on your selected aperture.
* ND Filters: Use ND filters to reduce the amount of light entering the lens, allowing you to use wider apertures in bright light while maintaining proper exposure.
In conclusion, ditch the "f/16 or bust" mentality. Learn about depth of field, lens performance, and diffraction, and then make informed decisions based on the specific scene and your desired outcome. Experimentation is key to finding what works best for you and your gear.