Posts Tagged ‘f/8’

Posted by M.Kumar at 31 July , 2009

F-Stop Definition

F-Stop is a unit to express how much light is entering a camera lens. Example f/2, f/4, f/8, etc.

Explanation

Assuming this post is for beginners I am briefing out the dependent terminologies: Aperture: Just like our eyes, camera lens has an opening that allows light to enter into the camera. This opening is termed as aperture. Focal Length: Distance between the image sensor and optical center of camera lens. When you buy a lens for your camera, it will have a number on it, something like 18mm, 55mm, 105mm, etc. These numbers are called as focal length. Letter “F” in F-Stop is called as focal length. Focal length divided by aperture determines the F-Stop.

Calculating F-Stop

For a 200mm lens with an aperture 50mm: F Number = Focal Length/ Aperture = 200/50 = 4 Finally denoted as F/4
For a 200mm lens with an aperture 25mm (decreasing the opening): F Number = Focal Length/ Aperture = 200/25 = 8 Finally denoted as F/8

Focal Length

Aperture

F-Stop

Conclusion

200 mm

50 mm

F/4

Bigger lens opening results in smaller F-Stops More light enters when F-Stop is small

200 mm

25 mm

F/8

Smaller lens opening results in bigger F-Stops Less light enters when F-Stop is large

How does this affect your photography?

Change in f number has a very high impact on the image captured. You can actually blur out the unwanted object from your scene and still be able to get a sharp focus of your subject. This impact of changing f number is basically termed as “Depth of Field”. Pictures captured with a low f-number will tend to have your subject in sharp focus while leaving rest of the scene out of focus. This is often used in portrait photography or macro photography where the subject is given importance than the background. Following is a range of pictures of same object with different f-Numbers; see how a change in f-number has an impact over the projected scene:

f-Number

Image

Observation

  1. Lens opening is wide, allowing more light to travel to the image sensor resulting in a well exposed scene.
  2. Bright colors.
  3. Blurred background with sharp subject. (Shallow Depth of Field)

  1. Lens opening is less than the above due to which less light is allowed to travel in resulting in slightly less exposed scene than above.
  2. Color intensity is getting decreased due to less light.
  3. Background is less blurred than above.

  1. Lens opening is less than the above due to which less light is allowed to travel in resulting in slightly less exposed scene than above.
  2. Color intensity is getting decreased due to less light.
  3. Background is less blurred than above.

  1. Lens opening is less than the above due to which less light is allowed to travel in resulting in slightly less exposed scene than above.
  2. Color intensity is getting decreased due to less light.
  3. Background is less blurred than above.

  1. Lens opening is less than the above due to which less light is allowed to travel in resulting in slightly less exposed scene than above.
  2. Color intensity is getting decreased due to less light.
  3. Background is less blurred than above.

  1. Lens opening is less than the above due to which less light is allowed to travel in resulting in slightly less exposed scene than above.
  2. Color intensity is has decreased due to less light traveling to the sensor.
  3. Background is getting sharp now. (Narrow Depth of Field)

Conclusion

With an increase in f-Number the lens opening decreases; allowing less light to travel to the image sensor. Also with an increase in f-Number narrow depth of field is achieved.

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Posted by M.Kumar at 12 June , 2009

In Understanding Shooting Modes (Part-I, II and III) I explained some of the auto and advanced modes. I’ll explain other available modes like Portrait, Landscape, Sports, Macro, and Night in this part.

Other Modes

In today’s cameras many other modes exist which I will be briefing out below. Availability and indication of these modes depends upon brand to brand. These modes are basically preprogrammed modes provided by your camera manufacturer.


OLYMPUS-E-620-portrait Portrait Mode

This mode is mostly represented by a head-and-shoulders icon. It creates a shallow depth-of-field thus throws out the distracting background. Turn the dial to use this mode and your camera will take care of everything else.

OLYMPUS-E-620-landscape Landscape Mode

This mode is mostly represented by a mountain icon. It produces a maximum depth-of-field allowing lens to capture everything including background. This also produces an overall sharp image. Turn the dial to select this mode and your camera will pick the best settings to capture the scene.

OLYMPUS-E-620-macro Macro Mode

This mode is mostly represented by a flower icon. It activates the camera’s closest focus along with a greatest possible depth-of-field.

OLYMPUS-E-620-sport Sports Mode

This mode is mostly represented by an icon of a person running. Once the shutter release button is pressed, camera automatically chooses a combination of higher shutter speed and aperture to freeze the motion of the object in motion.

OLYMPUS-E-620-nightportrait Night Mode

This mode is mostly represented by an icon containing a star, a moon and human image. It uses a slow shutter speed to get maximum amount and length of light.

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Posted by M.Kumar at 10 June , 2009

In Understanding Shooting Modes (Part-I and Part-II) I explained Auto, Programmed and Aperture Priority Mode, I’ll explain and illustrate one of the other advanced modes called Shutter Priority Mode in this part.

Shutter Priority Mode

This mode lets you choose the shutter speed and the camera chooses the appropriate aperture (lens opening) for proper exposure.

Why to use Shutter Priority Mode?

Shutter priority will allow you to control how you capture your subject in motion. This mode is used when you want to increase or decrease the amount of blurring in the picture, the blurring is due to the motion of either the subject or the camera shake.

Try It

Visit some waterfall and experiment the following:

Slow Shutter Speed

  1. Mount the camera on a stable tripod.
  2. Turn your camera’s exposure mode dial to Shutter Priority.
  3. Lower down the shutter speed to 1 Sec (or any thing above 1 Sec).
  4. Focus the waterfall and press shutter release button.


Result Cameras shutter will allow light to fall on the sensor for 2 Sec, this will blur out the falling water giving it a smooth touch as shown below:

3737-Waterfall_slow

Fast Shutter Speed

  1. Mount the camera on a stable tripod.
  2. Turn your camera’s exposure mode dial to Shutter Priority.
  3. Lower down the shutter speed to 1/1000th Sec.
  4. Focus the waterfall and press shutter release button.


Result Cameras shutter will allow light to fall on the sensor for 1/1000th Sec, this will capture the falling water with a great speed thus freezing the motion:

3737-Waterfall_fast

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Posted by M.Kumar at 5 June , 2009

In continuation to Understanding Shooting Modes (Part-I) where I described the Auto and Programmed Modes, I’ll explain and illustrate one of the advanced modes called Aperture Priority Mode in this part.

Aperture Priority Mode

This mode lets you choose the aperture (lens opening) and the camera chooses the appropriate shutter speed for proper exposure.

Just like human’s eyes, lens of a camera has an opening called iris that opens and closes according to automatic or manual settings. This in optical terms also referred as “Aperture”. Changing the aperture settings changes the size of the opening which controls the amount of light the lens passes through to the image sensor.


Why to use Aperture Priority Mode?

This mode is used when you want to have control over depth-of-field. This is measured in f-stops i.e. f/1.4, f/1.8, etc. Higher f-stop numbers indicate smaller aperture and vice-versa.

The “f-number” is the ratio of distance from the sensor/ film to the optical center of the lens in your camera. When you buy a lens for your camera, it will have a number on it, something like 18mm, 55mm, 105mm, etc. These numbers are called as focal length.

FocalLength

To put all of this simple, when the aperture of a 200mm lens (focal length) is 50 mm (aperture opening) wide, your f-stop will be f/4, because the ratio of 200/50 equals four. If you “stop down” your aperture to half that size – 25 mm wide – your f-stop will be f/8. (200 divided by 25.) So the “f-number” gets larger as you let in less light.

What is Depth-of-Field?

Depth-of-Field is the distance between the closest sharply focused object to the lens and the farthest sharply focused object from the lens. Large apertures (lower f-stop) create shallow depth-of-field and the smaller apertures (higher f-stop) create greater depth of field.

This is a bit confusing. But I learned it using an example of 10 trees standing in a row. Lower f-stops will capture lower number of trees and higher f-stop will capture more numbers of trees.


More Light << f/2 f/2.8 f/4 f/5.6 f/8 f/11 >> Less Light

Aperture

Try it

Visit some nearby garden where you can locate a flower and experiment the following:

Shallow Depth-of-Field

  1. Turn your camera’s exposure mode dial to Aperture Priority.
  2. Lower down the aperture to f2.
  3. Focus the flower and press shutter release button.

Result The lower f number will generate a shallow depth of field, thus focusing only the flower, not the background.

Flowers etc 006 copy

Greater Depth-of-Field

  1. Turn your camera’s exposure mode dial to Aperture Priority.
  2. Lower down the aperture to f22.
  3. Focus the flower and press shutter release button.

Result The higher f number will generate a larger depth of field, thus focusing everything along with the background.

Flowers etc 006

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Posted by M.Kumar at 30 May , 2009

Today’s advance digital cameras basically perform automatically many of the tasks necessary for capturing a photo. The Auto mode or the Programmed mode is always a good option for beginners to shoot any scene. However, these modes don’t always produce up to the mark results. If you really want to utilize the power of your DSLR, you must learn and practice all the available modes.

Before discussing any of the available modes, we should understand exposure. Exposure is basically amount of light allowed to fall on photographic film (in case of a film SLR) or on image sensor (in case of a DSLR). The amount of light in a camera is controlled by setting the combination of Aperture and Shutter.


Auto (Point-and-Shoot) Mode

In Auto mode, it’s the camera that makes decision on what amount of light is allowed to fall on the sensor. Today’s digital cameras are intelligent enough to run their own algorithms to attain a best calculated aperture and shutter speed combination based on the projected scene. You don’t have to do anything more than to press the shutter release button. This method is also referred to as the “Point-and-shoot mode”.

Programmed Mode

Some cameras let you preprogram a number of settings like ISO, quality, white balance, aperture or shutter. These settings can be saved in a programmed folder which can be used later. Today’s cameras have prebuilt programmed modes based on the situation, you just have to turn the mode dial to the programmed settings and that is it.

Why to use Auto or Programmed Mode?

Using these modes cut shorts the time it takes for you to set the camera’s settings.  Based on the ideal situation and available auto/programmed modes, you just turn the dial and press the shutter release button.

I used these modes when I was a beginner because after shooting l could compare the EXIF data and learned what settings did camera chose based on the projected scene. So, go ahead with these modes only if you are a beginner and study each and every setting that camera opted for the scene. In my public gallery at www.tweakdynamix.com, you can view EXIF data for each of the photos that I took.

How to Use the Camera in Auto/ Programmed Mode?

Well; these are the quickest mode to shoot. Just turn the mode dial to Auto/ Programmed mode based on the scene and press the shutter release button. The camera will use its sensors to make its best guess at most suited f-stop and shutter speed required for a good exposure.

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