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Olympus E-1 Digital SLR
By Tan Joe-sie
Category : Digital Camera
Published by Jimmy Tang on Monday, 9th February, 2004
Rating : 4 out of 5 stars  
Price : SGD4288

Key Features - Part 1

Now that we have seen the camera’s specifications that are common to most digital SLR cameras, here are some extra key features that stands the Olympus E-1 above the rest.

Four Thirds System
How can we mention the Olympus E-1 and not talk about it’s Four Thirds system? Contrary to some belief that the term 'Four Thirds' actually refers to the image aspect ratio, the term actually comes from the 4/3-type dimensions of the image sensor.

The 4/3-type image sensor’s dimensions is smaller than the 35mm- and APS-type image sensor used in most digital SLRs while it is 4 to 5 times larger than the 2/3- and 1/1.8-type ones used in compact digital cameras. This particular image sensor size was said to be chosen by the Four Thirds design team as it optimally met different requirements such as:

  • The need for high image quality and avoiding noise,
  • Accommodation of different pixel sizes in the future, and
  • Allowing the use of a telecentric lens construction.

    Smaller body and lenses
    With this smaller image sensor size (as compared to the 35mm and APS-type image sensors), the imaging circle (the diameter of the area in which the subject is resolved) needed is smaller. Thus, the camera body and lenses can be downsized. For example, a 600mm telephoto effect can be achieved with a 300mm lens, reducing the size of the entire lens construction.

    Radical downsizing of lenses

    Improving light sensitivity and Signal to Noise ratio
    At the same time, the 4/3-type image sensor is larger than the 2/3- and 1/1.8-type image sensors more commonly used in consumer digital cameras. The larger image sensor translates to larger photodiode sizes, thereby improving the light sensitivity and Signal-to-Noise ratio.

    Dedicated Zuiko Digital Lenses
    Up till now, digital SLRs systems in the market have been based upon pre-existing lenses designed for 35mm film SLR cameras which have image sensor sizes equivalent to that of a 35mm or APS film. Film can be exposed by light coming from various angles, thus, most 35mm film camera lenses do not need to ensure that light only strikes the film straight on.

    35mm film camera lenses do not need to ensure that light only strikes the film straight on

    On the other hand, the image sensor used in digital cameras is a chip with pixels laid out at regular intervals on a grid, with photodiodes in the depression inside the pixels. Thus, light reaches these photodiodes most effectively only if the light is passed straight through the lens, hitting the photodiodes straight on. As such, if a 35mm film lens is attached to a digital camera, light hitting the image sensor at an oblique angle results in inaccurate colour reproduction, and insufficient brightness at the sensor’s periphery.

    Light hitting the image sensor at an oblique angle results in inaccurate colour reproduction, and insufficient brightness

    Therefore, Olympus has designed their Zuiko Digital lenses to ensure that light is passed through to the image sensor in a near straight line, even at the periphery. As a result, the captured image is supposed to have a truer color representation and sharper details even at the image edges.

    Light is now passed through to hit the image sensor straight on

    Possible future Lens Mount Standardisation
    As the Four-Thirds system standardises the diameter of the lens mount, image circle, and flanged-focal distance (the distance from the lens mount to the image sensor), there is a possibiity for the standardisation of the lens mounting system between manufacturers should they adopt the Four Thirds system in time to come. However, whether the time will come, is a whole other debatable matter altogether. So far, other than Olympus and Kodak adopting the Four Thirds system, only Fuji Film has agreed to participate in the new standard.

    To find out more about the Four Thirds System jointly developed by Olympus and Kodak, please click on the following link -> The Four Thirds System
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