Aperture, in simplest of it's terms, is an opening. To take this simple meaning to its more correct form, we shall say that, aperture is an opening that lets the light in for exposing the film/sensor. Diving further, a simple thumb-rule is bigger the opening, more the light.
Think of aperture as camera's window to the outside world. Light only comes into the room when the panes are open enough. In our case camera is a room and aperture (The opening is also called as diaphragm but I am not using the word because the word is too tricky to spell correctly. Lazy me!) is a window. Simpler now. This aperture is denoted by F Stops. An F Stop is a unit and a number accompanies it. They usually increment by 1/3rd or 1/2 stop in camera. Another seemingly crazy thumb-rule here is bigger the number, smaller the opening and vice versa. For example, F2.8 may take in a finger or two of an average sized male while and F32 may or may not even take a needle tip. Ok now. What I forgot to mention that it was a highly hypothetical example. To tell you the truth, every lens's F2.8 is different. This aperture opening size actually depends upon the size of the lens; more specifically size of it's diameter. This is a very intricate and mathematical detail of photography into which I'll dive later.
So how does this light barricade (yet another metaphor!) affects our exposure? Aperture, like shutter-speed affects the image look in two ways. One direct way is by controlling actual amount of light that gets in during the said time of shutter speed, it directly affects the brightness levels of the image. So the time for one more thumb-rule arrives. I am sorry that we are probably ending up having more thumb-rules than thumbs we have. Smaller the number, bigger the aperture, brighter the image!
But things aren't so simple. It's second and so indirect effect is about depth of field. Now think of lens/aperture as a barrel of a gun. Now without diving into engineering of guns and related technologies, we can safely state that smaller guns tend to have better accuracy than their bigger barreled counterparts. For example, user skill keeping hypothetically aside, a handgun or even rifle may miss the target by only a few millimeters but even accurate-most cannons miss their targets by a few meters! This may be almost blasphemous to ask you to apply this logic to apertures and their due effect on depth of field!
But let's do it now. The bigger apertures like F1.4, F1.8 or F2.8 are cannons while comparatively smaller apertures like F9, F10, F11, F13 are smaller guns. To understand this blasphemy, I must introduce you to a bit of light theory. Science states that pure white light is made up of Red, Green and Blue coloured light rays. These different colours denote their different wavelengths. Now what actually happens when we turn the focus ring or autofocus the image that we want to shoot?
Suppose we are photographing a flower. In order to do that, we bring the flower in focus, i.e. we concentrate all light falling on and reflecting from the flower onto our camera sensor/film plane. At this exact juncture that handgun-canon blasphemy comes into play. Bigger apertures make this focusing (concentrating light reflected from subject) a tedious job. Due to their bigger sizes, light coming from only small part of the flower actually gets concentrated on the image plane. Hence a shallow depth of field/focus is lent by this cannon apertures.
The bottom-line being, aperture affects an image in two ways i.e. brightness and DOF. There cannot be another thumb-rule (Thank God!) when to use which aperture as each image’s requirements are different. Bigger apertures will give you a brighter image and a shallow depth of field comes free with it. Smaller apertures give you a deeper depth of field and in return would make an image considerably darker.
That’s all for aperture now. I’ll cover ISO next time. Stay tuned till then.
Think of aperture as camera's window to the outside world. Light only comes into the room when the panes are open enough. In our case camera is a room and aperture (The opening is also called as diaphragm but I am not using the word because the word is too tricky to spell correctly. Lazy me!) is a window. Simpler now. This aperture is denoted by F Stops. An F Stop is a unit and a number accompanies it. They usually increment by 1/3rd or 1/2 stop in camera. Another seemingly crazy thumb-rule here is bigger the number, smaller the opening and vice versa. For example, F2.8 may take in a finger or two of an average sized male while and F32 may or may not even take a needle tip. Ok now. What I forgot to mention that it was a highly hypothetical example. To tell you the truth, every lens's F2.8 is different. This aperture opening size actually depends upon the size of the lens; more specifically size of it's diameter. This is a very intricate and mathematical detail of photography into which I'll dive later.
So how does this light barricade (yet another metaphor!) affects our exposure? Aperture, like shutter-speed affects the image look in two ways. One direct way is by controlling actual amount of light that gets in during the said time of shutter speed, it directly affects the brightness levels of the image. So the time for one more thumb-rule arrives. I am sorry that we are probably ending up having more thumb-rules than thumbs we have. Smaller the number, bigger the aperture, brighter the image!
But things aren't so simple. It's second and so indirect effect is about depth of field. Now think of lens/aperture as a barrel of a gun. Now without diving into engineering of guns and related technologies, we can safely state that smaller guns tend to have better accuracy than their bigger barreled counterparts. For example, user skill keeping hypothetically aside, a handgun or even rifle may miss the target by only a few millimeters but even accurate-most cannons miss their targets by a few meters! This may be almost blasphemous to ask you to apply this logic to apertures and their due effect on depth of field!
But let's do it now. The bigger apertures like F1.4, F1.8 or F2.8 are cannons while comparatively smaller apertures like F9, F10, F11, F13 are smaller guns. To understand this blasphemy, I must introduce you to a bit of light theory. Science states that pure white light is made up of Red, Green and Blue coloured light rays. These different colours denote their different wavelengths. Now what actually happens when we turn the focus ring or autofocus the image that we want to shoot?
Suppose we are photographing a flower. In order to do that, we bring the flower in focus, i.e. we concentrate all light falling on and reflecting from the flower onto our camera sensor/film plane. At this exact juncture that handgun-canon blasphemy comes into play. Bigger apertures make this focusing (concentrating light reflected from subject) a tedious job. Due to their bigger sizes, light coming from only small part of the flower actually gets concentrated on the image plane. Hence a shallow depth of field/focus is lent by this cannon apertures.
The bottom-line being, aperture affects an image in two ways i.e. brightness and DOF. There cannot be another thumb-rule (Thank God!) when to use which aperture as each image’s requirements are different. Bigger apertures will give you a brighter image and a shallow depth of field comes free with it. Smaller apertures give you a deeper depth of field and in return would make an image considerably darker.
That’s all for aperture now. I’ll cover ISO next time. Stay tuned till then.
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