Before you head on for finding a perfect aperture for different shoots, here are few things you need to know very clearly. So,
What is an ‘Aperture’?
Remember the previous post on shutter speed where we discussed about the blinking of the eyes? Aperture can similarly be compared to the eyelids of the eyes.
Aperture is the lens diaphragm opening inside a photographic lens. The size of the diaphragm opening in a camera lens regulates the amount of light passing through onto the film inside the camera the moment when the shutter curtain in camera opens during an exposure process.
The size of an aperture in a lens can either be a fixed or usually depicted in f-numbers or f-stops. f/16 will let in 1X the amount of light than a diaphragm opening of f/22 and so forth; while on the other hand, an aperture of f/4.0 will let in 1X lesser than that of f/2.8 etc.
f/5.6 on a wide angle lens will not have the same diameter as another. Basically f/2 is half the diameter of the opening. According to calculations f/2.8 would give you twice the amount of light as f/4.0 and hence decreases by one stop. Hence with a difference of one stop, the aperture are defined as- f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22.
BIG aperture is actually referring to a smaller number engraved on the aperture ring of the lens i.e. f/1.4, f/2, f/2.8, f/4.0 etc. while small apertures mean bigger numbers i.e. f/22, f/16, f/11, f/8 etc. Basically, large aperture (f/2.0, f/2.8 etc.) lets in more light to the camera shutter for an exposure, while small aperture (f/11, f/16, f/22 etc.) has a smaller opening in the lens diaphragm to let in LESS light for a given exposure.
Other than controlling the amount of light entering into the camera, What else does “Apertures” do ?
When the shutter button is released, light passes through the aperture diaphragm and hit the film, an exposure is formed. Basically, aperture, along with duration/timing of the shutter curtain opening, BOTH contribute to a the formation of an exposure. But aperture also affects an important photographic element called “depth of field” (short form “DOF”). Depth of field is just technical term used to describe the ‘zone’ of sharpness’ between nearest and furthest of a subject in focus (to be more exact, distance of sharp focus in front and behind, subject on which the lens is focused).
The lower the f/stop—the larger the opening in the lens—the less depth of field—the blurrier the background.
The higher the f/stop—the smaller the opening in the lens—the greater the depth of field—the sharper the background.
Larger aperture with smaller number like f/2.8, f/2.0 etc. with a long focal length will isolate or give attention on expression, such as in portraiture photography. Smaller aperture with bigger number like f/16 or f/22 etc. will give pin-sharp details in both the foreground and the background of the object.
But high aperture means less light and low aperture speed means more amount of light entering.
Depth of field depends on-
1. Lens opening- Bigger the aperture used, less sharper your zone of focus becomes
2. Focal length of the lens- wide angle lenses have extended field of sharpness than a longer focal length telephoto lenses.
3. Distance of object from the lens- nearer the subject is, the shallower the zone of sharpness and vice versa.
Uses of different types of aperture-
f/1.4: Ideal for shooting in low light it can be best used on shallow subjects or for a soft focus effect.
f/2: The range has much the same uses, but an f/2 can be picked up in place of f/1.4 if that exactly does not suites.
f/2.8: More definition in facial features as it has a deeper DoF and can be used in low light. Zoom lenses usually have this as their widest aperture.
f/4: Minimum aperture you’d want to use when taking a photo of a person where there is decent lighting if you fear of your object getting out of focus.
f/5.6: Good for photos of 2 people but not in low light.
f/8: This is good for large groups as it will ensure that everyone in the frame remains in focus.
f/11: This is often where your lens will be at its sharpest so it’s great for portraits.
f/16: Used when enough natural light usually sunlight is present around the object. This enables you to get quite a sharp image of the object.
f/22: Best for landscapes where noticeable detail in the foreground is required
Remember – a perfect combination of shutter speed and aperture can help you achieve your masterpiece.
Keep practising !