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What is Aperture (F-stop) and its impact on DSLR photos.

If you are planning to move out of auto mode DSLR shooting, this post will help you with one of the most basic aspects of taking photos in Manual mode. Aperture is the opening or hole in the lens through which light travels when taking photos. This opening is made up of individual blade elements and the value of aperture forms an important part of the exposure triangle for photography. 
Lower f-stop value -> Wider is the aperture opening -> More light comes in.
Higher f-stop value -> Smaller is the aperture opening -> Less light comes in.

Whenever the value of aperture is changed, the amount of image sharpness and image exposure is affected. Also, changing the f-stop value is not as simple because the lens optics play a role here too. Coming to lenses, there are fixed f-stop zoom lenses and variable f-stop zoom lenses. As an example, Canon 70-200 F2.8 L IS USM is a fixed f-stop zoom lens and Canon 70-300 F4.5-F5.6 DO IS USM is a variable f-stop zoom lens. Why is this important? This is because you can always go higher than the minimum aperture value supported by your lens. Example: For a Canon 70-300 mm F4.5-5.6 lens, you can always set any higher value like F5.6, F8 in camera irrespective of the focal length you are at. For lower f-stop values, the camera functionality will not let you go below F4.5 as that's the optical limitation of the lens and camera-lens always have to work together. Image examples below will make it more clear how aperture affects the overall image. All 6 images were taken with the same shutter speed and ISO, only the aperture value was changed. 
DSLR settings: 
ISO: 160
Shutter speed: 1/200 seconds
DSLR: Pentax K5-II
Focal length: 18 mm
Lens used: Pentax 18-55 mm smc DA


impact of aperture
F/3.5

Impact of aperture on photos
F/4.5

Impact of aperture
F/6.3

Impact of aperture
F/9

Impact of aperture
F/13

Impact of aperture
F/18

From the above photos, you can see that the exposure of image drops with an increase in the value of aperture (f-stop). In addition to this, the other two factors to notice here are the image sharpness and bokeh amount. As the aperture value is increased, the image becomes sharper and more background area comes into focus. This is the reason landscape shots are usually taken at higher aperture values. For a super shallow bokeh (background blur in beginner terms), minimize the distance between your camera and subject, at the same time increasing the distance between your subject and background.

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Comments

  1. Good job! I enjoyed the entire post. Its time to buy a DSLR for me

    ReplyDelete
  2. It's nice to know the technics of it! I'm still learning all the time x

    ReplyDelete
  3. Very informative, I learnt a lot!

    ReplyDelete

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