Saturday, February 28, 2009

Modes of Shooting in Digital Camera

All digital cameras, either point and shoot, compact or dSLR have a variety of auto or preset shooting modes. These modes are usually (as in Sony Cybershot and Olympus)

  • Auto
  • Close up / Macro
  • Portrait
  • Landscape
  • Action
  • Night
  • Panorama
  • Program (P)
  • Shutter Priority (S)/Time Value (Tv)
  • Aperture Priority(A)/Aperture value(Av)

As the name suggests, in Auto mode everything is automatic, with camera taking complete control of all the settings. It will set the ISO, white balance and focusing mode, etc. etc.. This mode is often used by beginners or new users as it almost guarantees a correctly exposed and sharp image.

Close-up / Macro:

The Close-up or Macro mode is used to take close-up pictures of small subjects. The depth of field is very narrow in this case. However if you want the entire subject to be in focus you shuould shoot from directly above or directly below the subject so as the much of the subject as possible is at the same distance from the lens.

Portrait: In this mode the camera will set the largest possible aperture to create a narrow depth of field.This throws the back-ground out of focus so that more empasis is placed on the subjects face.


This mode works on the oppsite way to Portrait.The camera will set the smallest possible aperture to create the widest possible depth of field.This ensures that as much of the scene(and ideally from foreground to background)is in focus.


When photographing any fast moving sport or action scene.The camera will automatically select the fastest poosible shutter speed (depending on the available light) in order to freeze the action.You'll usually have better success if you follow the subject through the lens for a few seconds before taking the shot.


The night mode is designed to take portrait photographs in low light.The camera will set a relatively long shutter speed to ensure that the dark background is capturedwhile firing the flash to light and freeze the subject.This is known as "slow sync".You should always make sure that your subject remains still even after the flash has fired as the camera may still be recording.


In this mode,after the first image is taken the exposure and white balance are "locked" so that all subsequent images have the same colouration,tone, contrast.You then take the next picture and align the image with the previous one, of which about a third appears semi-transparent on the LCD screen.

Program (P):
Selecting P will allow you to change the ISO setting, image size and quality,the metering mode and a number of other settings that are set automatically when the camera in the auto mode. Detail about ISO settings was discussed in my previous blog on ISO, sensitivity and noise in digital camera.

Shutter Priority (S)/Time Value (Tv):

In this mode you can set a specific shutter speed( fast to freeze action or slow to deliberately blur objects).The camera will set an appropriate aperture depending on the available light. Above picture was taken with slow shutter speed to give blurry effect to water fountain.

Two pictures are shooted with different aperture speed to show aperture speed's effect on the flowing water. Picture on left is taken with shutter speed =1/4 sec. Picture on right is shooted with shutter speed = 1/500 sec.

Aperture Priority(A)/Aperture value(Av):
This mode works in similar way to (S)/(Tv) mode but the opposite way around. You can set a larger aperture to throw background out of focus or set a small aperture to increse the depth of field (to ensure a landscape is in focus from foreground to background).The camera will automatically select an appropriate shutter speed .

Picture on left is taken with larger aperture (Fstop = f/5.6) and on right is with smaller aperture (Fstop = f/22). You can observe how the background changes with the change in aperture.

Next I will discuss about the metering modes and histograms.

Saturday, February 21, 2009

ISO, Sensitivity and Noise in Digital Camera.

According to me a good camera is one which can take clear picture in low light without flash. This feature is achieved by ISO settings. Those who are familiar with film photography will know that different films have different ISO ratings. Even though your camera is most likely not film at all, but rather digital, the ISO setting still does has the same function as older film cameras. ISO determines how sensitive the image sensor is to light. A compact camera like Sony Cybershot have ISO settings of 50, 100, 200 and 400, while a digital SLR will often feature incremental settings of 100, 200, 400, 800, 1600 and 3200. Olympus E420 has a range from 100 till 1600. Higher the ISO setting, the more sensitive the sensor is to light which means signal created by light striking the sensor is amplified to greater degree.

Advantage of high ISO setting - avoid camera shake in low lights.

There is a direct correlation between shutter speed and ISO settings. By increasing the ISO settings, the shutter speed increases proportionately, for example, from 1/15 sec at ISO 50, the shutter speed increases to 1/30 sec at ISO 100 and 1/250 sec at ISO 800. At these later speeds, you'll avoid camera shake and can freeze slow movements.

Disadvantage of high ISO settings - causes grainy picture.

Unfortunately, there is a drawback to using high ISO settings as mentioned earlier amplifies electric signals which is applicable for background noise too which is present in camera's circuitry. This distorts the image signal and creates a speckled or noisy image.

Top left picture (Pic 1) is taken with ISO settings set to 100 and shutter speed was adjusted to 1/3 seconds. Top right picture (Pic 2) in right is the magnified version of Pic 1 which shows that the picture is slightly blurry because of hand shake while clicking the camera.
Bottom left picture (Pic 3) is taken with ISO settings set to 1600 and shutter speed was adjusted to 1/50 seconds. Bottom right picture (Pic 4) in right is the magnified version of Pic 3 which shows that the picture is grainy because of background noise. (click on picture to enlarge)

General Rules and tips for ISO Settings:

  • Use an ISO of 100 or 200 when taking photographs outside in sunny conditions.
  • If the sky is overcast or it is evening time, then use an ISO within the range of 400 to 800.
  • Night time or in cases of low light you might need to set your digital camera ISO to 1600.
  • Use Tripod if taking photographs at low ISO settings in overcast / low light conditions.

How to reduce noise from the picture.

  • Use camera which has got larger sensors because larger photosites found on such sensors collect light more effectively and thus don't need as much amplification to capture a poorly lit scene as a small sensor.
  • Now there are lot of photo editors in market (Adobe, Photosuite, Picassa) which helps to remove noise.

Next I will discuss about interesting stuff : Shooting and Composition.

Saturday, February 14, 2009

Digital Photography - Pixel and Resolution

My first experience with digital photography was in 2000 when my uncle presented a 0.5 MP Kodak digital camera. It was an amazing present I liked it a lot and started admiring digital photography from then. Things which I liked about digital camera as compared to analog camera was I can see my shots results instantaneously in the LCD screen and there is no recurring cost of developing and printing to view your shots. You just need to take your shots, connect the camera to computer and download pictures to computer and after that you can email it to your families and friends.
Building blocks of digital cameras is PIXELS, which is a short for 'PIcture ELementS'. An individual pixel carries information that governs its color, the strength of that color, and how light the pixel is displayed. In photography terminology these are termed as (HSB)
  1. Pixel's Hue,
  2. Pixel's Saturation, and
  3. Pixel's Brightness.
Each image is made up of million of pixels and number of pixel that an image has dictates the image's resolution.
More Pixel means

  1. Higher Resolution.
  2. Large Print Size.
  3. Large Disc Space.

Pic 1 is taken from 2 MP camera has 1600 x 1200 pixels, size on Hard Disk is 177 KB.

Pic 2 is taken from 6 MP camera ( Sony Cybershot) has 2816 x 2112 pixels, size on Hard Disk is 1.5 MB.

Pic 3 is taken from 10 MP camera (Olympus E420) has 3648 x 2736 pixels, size on Hard Disk is 1.9 MB.

As you might have noticed even though these pictures are taken from different camera of different pixel but still their clarity is pretty much same. That is because of Screen resolution / Print resolution which is measured in pixel per inch (ppi). Photo quality prints is 300ppi and computer's monitor has a standard resolution of either 72ppi (Windows) or 96 ppi (Macintosh). Which means if print area is small lesser megapixel camera will give almost the same kind of clarity as of high megapixel camera. Yes if we need to blow up this image then pic taken from 2MP will be most destorted and from 10 MP camera will be least.

So if we need to take pics to email friends and families and to get small prints we can achieve the same using lower MP camera and no need to spend money on higher MP cameras.

Below is the table which helps to determine what is the best print you can get from the range of 2MP - 12 MP cameras.

Next I will be discussing about ISO and Noise in Camera