Different apertures allow us to provide a unique “look” in the images we deliver to clients. A look that a point and shoot or a cell phone camera can’t achieve. Of course any serious photographer understands that the cameras we use, with larger sensors, are one of the necessary aspects of the creative use of aperture.
However here are 3 more characteristics of aperture that will provide you with tools to take greater advantage of how this can set us apart from the “point-and-shooters.”
1. Full Stops
Apertures are measured in what is called a “stop”. Simply put, when you “open up” the aperture of a lens by one full stop, you will get twice the amount of light passing through the diaphragm. Oppositely, closing down the aperture will decreases light transmission by half, which is also a stop. In other words, one stop brighter is 2x the amount of light, and one stop darker is 1/2 the light.
By default, most cameras will adjust your aperture by one-third of a stop. For example, to change from an aperture of f/2.0 to f/2.8, which is one full stop, you would click your aperture wheel 3 times from f/2 to f/2.2, f/2.5, and then f/2.8. For example, by the way, the most common full stop apertures are f/1.4, f/2.0, f/2.8, f/4, f/5.6, f/11.
Some camera models allow you to adjust in half or full stops, by customizing the function in your camera’s menu. TIP: Some photographers prefer to use 1/2 stops because it allows them more overall adjustments “per click”.
Other settings that fall in between, f/2.5 or f/6.3 are fractions between whole stops. Oldschool photographers, for example, might refer to f/2.5 as “f/2.0 and 2/3”. Even for new photographers though, being aware of full stops is important when balancing out your exposure triangle.
For example, a shutter speed of 1/200 and aperture of f/2.8 will give you the same overall exposure as a shutter speed of 1/400 and an aperture of f/2. Why? Because when your shutter speed went “up”, your aperture went “down” to compensate. Your shutter speed let in less light, so your aperture let in more light. This is useful when you want to use aperture to achieve a different “look” in your images, but without changing your exposure.
Blurry backgrounds are great, everybody loves them because they help “isolate” your subject. However as everybody should also know, stopping down your aperture makes your images sharper. But did you know it can also increase the possibility of softer images, due to something called diffraction?
A lot of the time I get people asking me questions about their issues with sharpness, and it turns out they were shooting their images at f/16 or f/22 because they thought these were the “sharpest apertures”. On paper this sounds correct and logical, but in the real world it is wrong. But how?
Diffraction is defined as a marginal bending of light as it passes around any object. The amount of diffraction has a few varying factors including size of the light source, distance from the object, and also the shape of the light source or object.
The simple explanation? If you stop down your aperture too far, your images will get “fuzzy” and start to lose fine detail. For example on a crop-sensor DSLR you may want to avoid apertures such as f/16 and f/22, or on a full-frame camera you may want to at least avoid f/22.
3. Optimum Aperture
As we just said, most lenses aren’t performing at their best at wide open apertures. Although the bokeh is beautiful and the depth of field easily isolates your subjects, you can achieve a sharper image by closing down just a little.
Of course you can easily test the optimum aperture for a lens by shooting a subject at different apertures. For this test, have your camera on a tripod and shoot the subject at the same focal length, without re-focusing in between images. Review your images at 100% on a computer screen, and compare which images are rendered sharper.
You should be able to easily determine two things: When your lens gets “acceptably sharp”, and also when your lens begins to suffer from diffraction like we mentioned above.
When I shoot runway for example, I tend to shoot between f/2.8 and f/4. Each venue is lit differently and I don’t always have the luxury of a high shutter speed unless I want to sacrifice my ISO. After testing out 3 different apertures, f/2.8, f/4, and f/5.6, I discovered I had the most success (being consistently sharp) at f/4. I love the depth of field at f/2.8 but sometimes when the models are walking swiftly I have to remind myself that I need both the model and their wardrobe to be tack sharp so I bump my aperture to f/4. This also gives me a little more sharpness which is important for editorial types of photo shoots, compared to say “lifestyle” portraiture.
We as portrait photographers tend to want to shoot ‘wide-open’ a lot because of the bokeh effects, and oppositely many new landscape photographers (or similar) might try to “stop down” all the way for the most depth of field or optimal sharpness. However, understanding the appropriate situations on when to shoot open or closed, or high aperture and low aperture is very important.
So, when shooting children, babies, or families, a soft image may be desirable. Other times, we may want to render everything in focus and sharp so shooting at a high aperture makes sense. Just do your homework first, and figure out which situations work best for your style and tweak as necessary. These 3 characteristics, when used properly, will greatly help you shape the identity of your photographic style.