DSLR Camera Explained

by Waqar Ul Hasan - ( 08-05-2017 )


Light is the most fundamental element in photography. Technically speaking, it is the only element we need to take care, when using a DSLR Camera. So, it is crucial to understand, how we are going to save the amount of light needed to produce a great looking photo. So, lets examine, How much control a DSLR Camera offers us to reproduce the "Creative - Reality" we do experience in our daily life.

Following is a brief list of most common controls found in any DSLR. For my examples, I am using a Cannon 550D. (A very convincing Starters DSLR)... So, the first thing first;

My - Cannon 550D



Exposure


In simple words, Exposure controls, how dark or light an Image will be taken by the Camera. So, Exposure is the amount of light per unit area reaching to the electronic image sensor [1].

Too much of light will result an Over-Exposed photo (A very bright Image, where most of the stuff in the image will be washed out). Same as the less light will also result an Under-Exposed photo (A dark image).

Mainly a Camera Exposure is tuned by the Aperture, Shutter Speed and ISO. And controlling these three sets of settings allow us to capture optimal photo quality. Also these settings allow us to add special effects like depth-of-field, blurriness, sharpness, in-motion or freeze motion effects to our snapshots.



1 - Aperture


Controls ? ( Amount of Light by the size of Lens and Lens-Opening, Depth-of-Field, Focal Point, Blurriness and Sharpness )

The Aperture ? (Aperture-Hole) controls the amount of light which can be passed into the camera. And it is the very first important place, where we control our Exposure.

Aperture is controlled by the Lens. So, the Lens has one side that is wide-open; where the light gets in. In the middle, by traveling through the series of lenses; it gets focused. And at the end, it passes the Aperture-Hole (or Iris Opening). So, the effects like Depth-of-Field, Focal Point, Blurriness and Sharpness happened in the Lens first.

Usually a Camera Lens is a combination of multiple lenses arranged togather. If you like, you could read more in detail about Lens Basics (raw) and Camera Lenses as well as Telescope Lenses.


Aperture - Canon 50mm Lens
Image is taken from Wiki-Pedia.



Aperture Measurement: ( f-Stop Number )


Aperture or the (Aperture-Hole) is measured in f-stop Numbers. The typical f-stops values are mentioned in the image above. F-stop number varies depending on the size of the Aperture-Hole or Iris-Opening of the Lens.

  • The bigger the f-number like f/11 or f/16 - the smaller the opening ( Aperture-Hole) will be. The smaller Aperture-Hole provide more depth-of-field. Which results a more focused and sharp image. Usually, Smaller-Aperture is used in Landscape photography, where the whole scene is in focused. In other words when we are focusing distant objects or the infinity.
  • Same way, the smaller the f-number like f/1.4 or f/2.8 - bigger / wider the opening (Aperture-Hole) will be. The bigger Aperture-Hole gives us less depth-of-field. There for give us the possibility to bracket our subject-of-interest when shooting closer objects or specific object in our scene. So, the bigger f-number is used in the Portrait, Macros or Closed-Up shots.

Aperture - F-Stop Numbers



Depth-of-Field:


As mentioned above, It is basically the area which is in focus or Bracket. Or where part of image is in focus on the subject and the background or rest of the image is blurred. Usually, Depth-of-Field is being used in the Portrait photography. Same way, when the whole image is focused-sharp; there is no depth-of-field and no blurriness. As it is used in the Landscape photography.



2 - Shutter Speed


Controls ? ( In-coming Light over Time, in-Motion / Motion Blur and Freeze Motion effects)

Second Place, that helps us to control the Exposure is the Shutter Speed or Exposure Time that can completely Block or Unblock the light passing through the camera. So, between the Aperture and Camera Sensor there is a physical Shutter. Which is controlled over time. Meaning that we can control the shutter opening in milliseconds, seconds or in extreme cases in Minutes. Usually it is 1/4000 of a second to 1/40, 1/30, 1 sec, 2 sec, 5 sec,.... etc. displayed on the Shutter Speed control available on the camera. The default state of the Shutter is Closed. When we press the Button on the camera to take the snapshot, then it gets opened for the time we specified in the Shutter Speed Control.



Shutter Duration / Exposure Time


It is very important to understand the proper duration of the Shutter Speed or Exposure Time. By using wrong speed can result an under-exposed or over-exposed photo. Following is the general usage and general measure for the shutter speed.

  • The faster shutter speed is used when (1/8000, 1/4000, 1/800 of a second)
    • There is lots of light, like a Sunny Day in order to prevent the over-exposed shot.
    • When Subject-of-interest is moving fast. Like a Sports Car or an Aircraft at the Expo-Show, or Capturing a Combustion Effect... etc.
    • So the faster Shutter Speed will Freeze the motion as well.
  • The Slower shutter speed is used when (1/40, 1/10, 1", 5", 30" of a second)
    • There is less amount of light, A cloudy day, indoor, evening or for the night photography
    • When Motion-Blur or motion of the subject is desired. Like rotating propeller of an Aircraft, a flying Bird's wings or fountain shooting water smoothly.
    • So the faster Shutter Speed require that the camera must not move, rotate or shake on its Pivot. Usually a Tripod is used for that purpose. To achieve the motion-blur effects or a moving effect on the subject in the snapshot. As well as Night or Astro-Photography. Where shutter can be opened from 30" seconds to couple of minutes.
    • When special effects are required and we are feeling little creative :)



Recipe Chart for Shutter-Speed


Usage Shutter-Speed Visual Effect
Fast moving Subject, Racing Cars, Aircraft 1/2000 or 1/4000 and more... Freezed motion
Sports / Gymnastic Athelets 1/1000, 1/1500 -
Still life Portraits 1/60, 1/250 Natural
Landscapes 1/20, 1/100 Standard, little or no Motion-Blur
Waterfall 2", 20" Smooth motion with motion-blur
Night / City-Life 8", 30" and more Motion-Trails of illuminated Moving objects
Astro-Photography 30", 2 minutes and more Bright Sky with Stars, Milky-Way Shot
Astro-Photography / Creative Mode 30 minutes to 3 Hours In the night, Full of bright Stars, or spirals of moving Stars and so on.
Galaxy Shot, Milky-Way Shot


3 - ISO (illumination, saturation, ISO Standard)


Controls ? ( Light Sensitivity to Image Sensor, Noise or Grain / (Film Grain) )

The third place where the light gets fine tuned is on the Image Sensor. After the light passes the Shutter's Opened-State, It hits the Image Sensor. So, the ISO is the level of sensitivity at which the Image Sensor actually translate the Light into a digital Photo.



Exposure Meter


Exposure Meter is like a master control for Aperture, Shutter Speed and ISO. It effects all three settings together to make the Image brighter or darker. Usually it is used in HDR Images to capture the light intensity on a higher bit-depth.



Auto Exposure Bracketing - Auto Bracketing


... more in progress ! ...



Keywords : DSLR Camera, Light, Camera Lens, Exposure, Aperture, Shutter-Speed, ISO