The Argument for f/16 (or Narrow Apertures in General):
The core idea behind recommending f/16 (or similar small apertures like f/11, f/18, or even f/22) for landscape photography is to maximize depth of field. Depth of field is the zone of acceptable sharpness in your image. A larger (smaller f-number) aperture like f/2.8 has a very shallow depth of field, meaning only a small portion of the scene will be in focus. A smaller aperture like f/16 has a much deeper depth of field, theoretically keeping everything from the foreground to the distant mountains sharp.
* Sharpness Throughout the Scene: Landscapes often have elements at varying distances. You want the interesting rock in the foreground *and* the dramatic mountain range in the background to be sharp. A narrow aperture is the most straightforward way to try to achieve this.
* Tradition and Historical Context: Before the advent of powerful post-processing and advanced understanding of diffraction, landscape photographers often relied on small apertures as a matter of necessity. It was the only way to ensure sharpness throughout the image.
* Simplicity: It's a simple rule to remember and can act as a "safe" setting for beginners.
Why f/16 (Always) Is WRONG:
The "always" part is where the problem arises. Relying solely on f/16 ignores several crucial factors:
* Diffraction: This is the most important reason to question the blanket recommendation. Diffraction is a phenomenon that occurs when light waves pass through a small opening (like the narrow aperture of f/16). It causes the light to spread out, resulting in a *softening* of the image. The smaller the aperture (higher f-number), the more pronounced diffraction becomes. While f/16 might seem like it's increasing sharpness across the entire scene, it's actually *reducing* sharpness overall due to diffraction. You'll often get sharper results using a wider aperture (e.g., f/8 or f/11) even if the depth of field is slightly less.
* Lens Performance: Every lens has a "sweet spot," an aperture at which it performs optimally in terms of sharpness and minimal aberrations (distortions). This sweet spot is usually somewhere in the f/5.6 to f/8 or f/11 range, depending on the lens. Shooting at f/16 may take you far away from this "sweet spot"
* Sensor Size: The impact of diffraction is more pronounced on cameras with smaller sensors (e.g., micro four thirds, point-and-shoots). Full-frame cameras can generally tolerate smaller apertures slightly better before diffraction becomes too detrimental, but it's *still* a factor.
* Exposure Requirements: Using a small aperture like f/16 requires a longer shutter speed (to allow enough light to reach the sensor) or a higher ISO. Longer shutter speeds can lead to motion blur (especially if you don't have a tripod or if there's wind). Higher ISO can introduce noise into your image.
* Creative Control: Choosing your aperture is a creative decision. Sometimes, you *want* a shallow depth of field to isolate a subject and blur the background. Sticking rigidly to f/16 prevents you from exploring these creative possibilities.
* Focus Stacking: This is a technique where you take multiple images of the same scene, each focused on a different part of the scene, and then combine them in post-processing to create an image with extreme depth of field. Focus stacking allows you to use wider, sharper apertures and still achieve sharpness from foreground to background.
When f/16 (or Similar) Might Be Appropriate:
* When depth of field is absolutely critical and you can't use focus stacking: If you absolutely, positively need maximum depth of field and focus stacking is not an option (perhaps due to a rapidly changing scene or lack of post-processing skills), then f/16 (or even smaller) might be a necessary compromise. However, be aware of the potential sharpness loss due to diffraction.
* When you need a longer shutter speed for creative effect: If you want to blur water or clouds, a smaller aperture like f/16 can help you achieve a longer exposure, even in bright light. However, a neutral density filter (ND filter) is a better solution in this case, as it allows you to lengthen the shutter speed without compromising sharpness.
* As a starting point for experimentation: It's fine to *begin* at f/16 and then experiment by adjusting the aperture and observing the results on your camera's LCD or in post-processing. This is a great way to learn about depth of field and diffraction.
Better Practices for Landscape Photography Aperture:
1. Understand Your Lens: Research your lens to find its optimal aperture for sharpness. Test it yourself at different apertures.
2. Use a Tripod: A tripod is essential for landscape photography, allowing you to use slower shutter speeds without camera shake. This allows you to choose a wider aperture (and faster shutter speed) for better sharpness.
3. Focus Carefully: Use live view and zoom in to ensure you're focusing accurately on the most important part of the scene. Consider using hyperfocal distance or focusing a third of the way into the scene.
4. Evaluate Your Scene: Determine how much depth of field you truly need. Do you need *everything* sharp, or can you get away with a slightly shallower depth of field and a sharper image overall?
5. Consider Focus Stacking: Learn how to focus stack! This technique opens up a world of possibilities for landscape photography, allowing you to maximize sharpness while using optimal aperture settings.
6. Experiment! Don't be afraid to try different apertures and see what works best for you and your equipment. Examine your images closely to evaluate sharpness and depth of field.
In Conclusion:
f/16 is a tool, not a rule. It has its place in landscape photography, but it should be used thoughtfully and with an understanding of its limitations. Don't blindly follow the "f/16 and be there" mindset. Strive to understand the trade-offs between aperture, depth of field, and sharpness, and choose the settings that best suit your creative vision and the specific scene you're photographing.