Photo Basics that will Really Help if you Understand Them
This blog will be about basic information that is second nature to experienced photographers, but that can be incredibly confusing to neophytes! There is a basic relationship that exists between the ISO setting, shutter speed, and aperture setting on a camera. Now if this is too basic to some of my more experienced followers, please wait for the next blog and likely it will be less boring to you. To aspiring photographers however, complete mastery of this concept is totally required if you seek success with your photography.Exposure is a basic term relating to how an image is technically produced. I am not trying to run off anyone with all these words, however the concept is so important as to the making of an image that my intention is to to be slow and thorough for all who read this. Light reflects or is absorbed by the subject you have selected to make into an image. This light then moves through the lens for a fixed period of time, designated by the shutter speed, going through an aperture of a fixed diameter, at a speed designated by the ISO of the sensor. Now this statement can be “oh so confusing”! There are all kinds of sensors, however they all essentially react the same way. The sensor adjusts the data into a way for the camera to record the image you have photographed. I am stating this simply in order to make the information easy to digest. There is in photography a term EXPOSURE VALUE or (EV) that relates to the combination of settings that rendered the image on your camera. It is at this point that we need to understand what those values are named and what they do to make the image.
ISO This is the speed element of the equation. ISO actually means International Organization for Standardization. Being the elder statesman that I must admit to being, I was around when the ASA of a film was the related (although different) term that was meaningful. These days the ISO relates to the sensitivity of the camera sensor to light. (Similar to the sensitivity of the film to light). When the ISO or sensitivity of the sensor is set higher, then the less light that is required to make the proper exposure.
APERTURE This term is the f stop or measurement of the opening of the lens diaphragm. This aperture or diaphragm controls the volume of the light passing through to the sensor of the camera. A simple way used by many teachers to explain this is to consider water passing through a pipe. A bigger pipe allows more water to pass than a smaller pipe. See, easy!
SHUTTER SPEED This device controls the length of time that light passes through the Aperture to get to the sensor. Again using water in a pipe, the analogy would relate to a valve that shuts the water off at a particular time.
In a different blog I will discuss this area relating to what the sensor does but this time the relationship of these three functions are primary. The confusion or complexity of this concept now comes into view when you are told that several different manual settings on your camera will give you the same basic exposure! To understand this I would expect that you should go camera in hand outside on a bright day with plenty of sunshine and make several exposures using the following settings. Consider this our field trip!
Set your ISO to 100
Set your ISO to 200
Set your camera to complete manual mode. This will keep any variables from muddying the water so to speak! You may have variations in exposure because of the mechanics of a shutter dragging but that is unlikely. Expose the same image (subject) without changing composition in any way. Do this academically to prove a point. You should wind up with twelve identical pictures! We can at this point see a different depth of field in the images where the aperture is changed but the overall exposure will be verrrrry comparable.
Now what we have proved is that there exists a direct one stop relationship between the ISO, shutter speed and aperture.
Great post! I am just now helping some new-to-DSLR camera enthusiasts out, this is exactly where I start!
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