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Understanding Camera Functions and Settings

Manual mode is the way to go. Or more specifically, it is the way to unleash, develop, and maximize one’s creative potential to produce amazing images. Why? Shooting in manual mode facilitates a more engaged and enjoyable photographic experience that encourages and develops one’s creative talent. Having full control over everything the camera does forces one to think through every aspect of the production of the final image. To see something in the mind’s eye, and thoughtfully transform that idea into a beautiful photograph necessitates the full manual control of one’s camera. This is the difference between simple photographic documentation, and art.

A great photograph is more than simply its composition and framing. That is of course the first step and extremely important, but beyond that, one must decide upon a shutter speed, aperture, and ISO sensitivity. Light is the key to photography, and the manipulation of these three settings is the way to control the light that is coming into the camera and what dictates the appearance of the final image. Therefore, a proper understanding of these settings and how they work is critical to developing one’s photographic skill.

Let us first take a look at how an SLR works. Its primary job is to allow for a properly exposed image. This is accomplished through the regulation of thee variables. Film/sensor ISO sensitivity, shutter speed, and aperture.

Film/sensor ISO Sensitivity

A piece of transparent plastic film, coated with a gelatin emulsion of microscopically small light-sensitive silver halide crystals, darkens when exposed to light. Exposing film to the proper amount of light is what will make a properly exposed image. Not enough light and the image will be too dark, too much and it will be too bright. As such, it is very important to know how quickly film reacts to light. Thankfully, the rate of darkening is fixed per unit of light for a given film type. This rate is known as the film speed, or more commonly as an ISO rating (ISO being pronounced as a word, which it is). The slowest film speed typically sold is ISO 100 film. Film can also be had in ISO 200, ISO 400, and ISO 800. Each doubling of the ISO rating indicates a commensurate doubling of the film’s sensitivity. Thus, ISO 200 film requires half as much light as ISO 100 film to attain the same exposure. ISO 400 requires half the light as ISO 200 and one quarter the light as ISO 100 film. Or said another way, ISO 200 film will require half as much time given the same intensity of light as ISO 100 film.

Sony Full Frame CMOS Image Sensor

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The main way high ISO film is made to be more sensitive to light is by increasing the size, and decreasing the number, of silver halide crystal grains. Larger crystal grains of course can absorb more light than smaller ones and subsequently react more quickly. However, these larger grains, being larger, result in a more grainy, lower resolution image. Due to this, photographers generally opt for the lowest ISO they can manage in order to get the sharpest, least grainy images they can.

In digital photography, a digital CMOS or CCD image sensor replaces the film. Instead of silver halide crystals, photodiodes (interestingly also based on a metal oxide) make up the individual light sensitive pixels. A huge advantage of digital photography over film photography is the ability to change the image sensors ISO sensitivity at any time rather than being restricted to whatever ISO film happens to be loaded into the camera. Remarkably, the characteristic of high ISO film being grainier carries over to digital photography as well. However, especially with modern full frame digital image sensors, ISOs can often be pushed to and even beyond ISO 3200 before noticeable grain and image quality degradation occurs. This allows for shots that back in the film days, would have been impossible to make.

1/1600 vs. 1/80 seconds exposure time

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Shutter Speed

Directly in front of the image sensor, or film, is a shutter mechanism that opens and closes for a measured amount of time in order to expose the images sensor to a specific amount of light and make an image. The amount of time that the shutter is left open for is measured in seconds, and most often, fractions of seconds. It is extremely important that shutter speed be properly regulated. Too long and the image will be too bright, too short and the image will be too dark. Furthermore, because we live in a dynamic world, one must be careful to consider how much things, including the camera, could move during the time the shutter is open.

To get a sharp image and avoid camera shake (assuming of course proper focus), the general rule for a static subject is to shoot with at least a shutter speed equal to one over the focal length. So, if you are using a 50mm lens, a minimum shutter speed of 1/50th of a second is recommended. If a focal length of 200mm is being used, 1/200 would be recommended. Of course, with improved technique, optical image stabilization, In Body Image Stabilization (IBIS), and obviously a tripod, it is possible to successfully shoot with much slower shutter speeds. Just depends on how steady one can be.

However, if your subject is moving, or if you are moving, it is important to consider the degree to which the subject might move whilst the shutter is open. The longer the shutter is open for, the more time the subject has to move across the frame, and the blurrier the subject or scene will appear. Though, motion blur is not always a bad thing. In fact, it can be used to one’s creative advantage in loads of methods. One of my favorites is to convey motion. If I were to shoot a cyclist at a relatively slow shutter speed and pan with him while taking the shot, if done correctly, a motion blurred background will result while the cyclist will remain sharp.

Thus, if for instance I am photographing an airplane flying past me and want everything to be tack sharp with no motion blur whatsoever and I were shooting with a 300mm lens, rather than sticking with the guideline shutter speed of 1/300, I might have to double, or even quadruple my shutter speed to 1/600th or 1/1200th of a second respectively. Keep in mind though that by increasing one’s shutter speed, less light will be able to strike the image sensor and the final image will be quite dark. Thankfully, digital image sensors allow one to quickly and easily compensate for this by simply bumping up the ISO value. Let us say for example that my 300mm lens at 1/300th of a second let in just the right amount of light for a properly exposed image at ISO 100. Then, if I decided I wanted a shutter speed of 1/600th or 1/1200th of a second, all I would have to do is bump up my ISO from 100, to ISO 200 or 400 respectively.


Aperture is most easily described as the iris of the lens. Just like the human eye is designed to regulate light by the contraction and dilation of the iris, so too is a cameras lens able to dilate and shrink the opening inside of it to moderate light intensity. The size of this opening relative to the focal length is referred to as the f-number and is equal to focal length over aperture diameter. Due to this relationship, every time the f-number increases by a factor of √2 (about 1.41), the area inside the aperture, and thereby the amount of light transmitted, decreases by a factor of two. This is where the standard f-stops of f/1.4, f/2, f/2.8, f/4, f/5.6, f/11, f/16, f/22, and f/32 are derived. This means f/1.4 lets in twice the light as f/2, four times the light as f/2.8, eight times the light as f/4, and so on.

f/1.8 (wide open) vs. f/16 (stopped down)

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Besides light transmission, another critical component of aperture to understand is how it affects depth of field. Every optical instruments projected image must be focused at a certain point a given distance away from the lens. Everything in the frame exactly that distance from the lens will be in perfect focus. This is called the plane of focus. From that point, or plane of perfect focus, both towards and away from the camera, things will gradually become less and less focused. The rate at which things become less focused is a result of lens design elements beyond the scope of this article. Essentially, the larger the aperture, meaning a lower the f-number, the narrower the plane of acceptable focus will be and visa versa. The plane of acceptable focus is defined as the distance on either side from the plane of perfect focus in which the focus is close enough to perfect that the difference is negligible or even imperceptible from the plane of perfect focus.

f/2 (shallowest) - f/16 (deepest)

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Revisiting the airplane example, I could use my understanding of aperture and planes of focus to control the degree to which elements of my photograph are in focus. If I wanted the whole airplane as well as the mountains in the background to be in the plane of acceptable focus, I would have to stop the lens down to a really small aperture, maybe f/22 or even f/32. Of course, to do that I would be giving up a huge amount of light (32 and 64 times less light than f/2.8), so to maintain a properly exposed image, I would simply decrease the shutter speed, increase the ISO sensitivity, or likely a combination of both. Conversely, if I wanted to really isolate my subject with out of focus elements in front of and behind it, I would use a wide-open aperture of f/2.8 or even f/1.4. I would then compensate by lowering my ISO sensitivity and increasing shutter speed to create a properly exposed image.

Measuring Proper Exposure

The easiest way to determine proper image exposure in a DSLR is by looking at the exposure meter readings usually displayed in the bottom of one’s viewfinder. This meter will measure the amount of light entering the camera, take into account your chosen ISO, shutter speed, and aperture and display in stops of light how over or under exposed the image will be. This is of course a guess based on comparing the amount of light measured to an average amount of light predetermined by the engineers of the camera. Usually this guess is correct or at least close enough. However, these meters often get confused when the subject is very white or very dark. If I were photographing a bright snowy scene, my exposure meter would likely read all that light and suggest an exposure that is too dark. On the flip side, when photographing the milky way, my exposure meter will be essentially useless. Because the night sky has lots of black, it will suggest I crank up my exposure in order to allow for what usually would be a good amount of light. This of course would result in a vastly overexposed image. In such dynamic situations, having the ability to review one’s images right on the camera’s LCD screen is extremely valuable. (This is one distinct advantage of mirrorless cameras; they can show you exactly what the image will look like before you even take the photo)

Post Processing:

Post Processing Both under and over exposure, can be fixed in post processing (in the dark room for film, and on the computer for digital). Generally, one or two stops of light can be pushed or pulled in post without noticeable degradation to image quality. In order to extract such information from an image, it is critical that one be shooting in a RAW file type. This is extremely helpful because it allows for a great deal of raw information to be retained in the image for use in post processing. This added dynamic range allows for photographers to shoot a scene in one image that would otherwise be impossible. Though, it is important to remember that pushing an images exposure too far in post results in a decrease in contrast and overall image quality.

If you are shooting in a RAW file type, which if you care enough to read this you probably should be, then it is essential to process your images. This will take them from looking far worse than JPGs to far better than JPGs could ever dream of looking. There is a huge variety of software available for processing ones images from basic but surprisingly powerful free options to subscription based and extremely capable software. I highly recommend and have used both Capture One by Phase One or Lightroom Classic by Adobe.

Raw vs. Processed Image (pushed 1 stop and shadows lifted 1 additional stop)

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Salient Points

Understanding at least the basics of how cameras and their settings work will undoubtably make for a more enjoyable, creative, and productive photographic experience. Thus, it is critical to understand the three main settings of a camera: ISO Sensitivity, Shutter Speed, and Aperture.

ISO Sensitivity: The sensitivity of the image sensor/film to light. Often referred to as ISO speed, or simply ISO, is the rate at which the film or sensor will become exposed to light. Usually ranges from 100-12,800+, with higher values denotating a proportionally higher level of sensitivity.

Shutter Speed: Normally controlled by a mechanical shutter mechanism in front of the image sensor. Shutter speed is the length of time (usually fractions of seconds) that the image sensor is exposed to light. The slower the shutter speed, the more time light has to be absorbed by the sensor as well as for the subject to move. Faster shutter speeds light less light in but result in less motion blur

Aperture: The opening in the lens, analogous to the iris in the human eye, which can open and close to allow for more or less light as well as less or more depth in the plane of acceptable focus. Aperture is measured as the f-number and is equal to focal length over aperture diameter. A large aperture thus has a small f-number, allows a lot of light through, and results in a shallow plane of acceptable focus while a small f-number does the opposite.

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