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I copied here some information from the Olympus website about the new 4/3 system below. We also added a pdf file to the scan section, which was made by Olympus to explain the 4/3 system and its advantages. You can download it and read it offline. Just click on "scans" in the navigation bar or click on this link:
Olympus and Kodak Agree to Implement
Four Thirds System Digital SLR Camera Standard
First-of-its-kind common standard for digital cameras
Secures lens mount compatibility among manufacturers
New Universal Digital Interchangeable Lens System Forum to be established
Olympus Optical Co., Ltd. of Japan and Eastman Kodak Company of the United States today announced that they have agreed to implement the Four Thirds System (4/3 System), a new standard for next-generation digital SLR camera systems that will ensure interchangeable lens mount compatibility. The two companies have resolved to aggressively implement this new standard in their respective product lines, and to establish the Universal Digital Interchangeable Lens System Forum, an industry forum that will promote acceptance of the Four Thirds System by other camera manufacturers. Fuji Photo Film Co., Ltd. has already agreed to participate in the new standard.
About Four Thirds System
The Four Thirds System is not based on existing standards for 35mm film SLR camera system lenses, but instead establishes a new common standard for the interchange of lenses developed exclusively to meet the optical design requirements of digital SLR cameras.
4/3-Inch (Type) Image Sensor Size
The Four Thirds System uses a 4/3-type CCD, CMOS or other image sensor, and will facilitate the development of dedicated digital camera lens systems that maximize image sensor performance and ensure outstanding image quality while also being smaller and easier to handle than 35mm film SLR camera lens systems.
Lens Mount Standardization
By establishing an open standard for camera body and lens mounts, the new system will make it possible to standardize lens mounting systems, something that has been impossible to achieve with digital SLR cameras that are based on existing 35mm film SLR lens systems. In addition, the new system defines standards for image circle size (the diameter of the area in which the subject is resolved) and back focus distance (the distance from the lens mount to the image sensor).
Current digital SLR cameras with interchangeable lenses are basically based on conventional 35mm camera systems. As a result, they must be equipped with image sensors that are comparable in size to 35mm and APS film. However, because the imaging characteristics of these large CCDs are fundamentally different from those of film, a number of issues can prevent them from achieving their full performance potential. These include: (1) Although film is capable of responding to light striking the surface at a high angle of incidence, a high angle of incidence can prevent sufficient light from reaching sensor elements at the periphery of a CCD and result in reduced color definition, particularly when shooting with wide-angle lenses. (2) To achieve the resolutions required by the micron pitch of today's CCDs, the demands of optical design tend to result in the use of larger and heavier lenses.
Moreover, manufacturers of digital SLR camera systems have until now adopted the mounting systems used in their own respective 35mm film SLR cameras, making bodies and lenses produced by different manufacturers incompatible with one another.
In light of these circumstances, the new Four Thirds System standard was conceived to facilitate the design and development of digital SLR cameras and lenses that maximize the performance potential of digital imaging sensors, and provide users with product advantages such as compact size, handling ease, and enhanced functionality.
The major benefit of Four Thirds System is that it allows the design of dedicated, high-performance digital camera lens systems that are more compact than 35mm film SLRcamera lens systems. The impact of the more compact lens size will be especially marked on telephoto lenses, making it possible to produce a Four Thirds System 300mm telephoto lens, for ex&le, that offers performance equivalent to an approximately 600mm lens on a 35mm film SLR camera. In other words, it will be possible to offer the same angle of view in a lens that is only about one-half as long. The 4/3-type image sensor size will also allow the development of bright, high-performance zoom lenses that are more compact than those needed for use with image sensors the size of APS or 35mm film. By taking advantage of the more compact lens size, it will therefore be possible to develop lens systems that are much easier to handle than conventional 35mm film SLR camera lens systems.
Furthermore, standardization of the lens mounting system will make it possible for consumers to photograph combining with bodies and lenses produced by different manufacturers, and enjoy a wider range of product selection.
I hope this informat helps to get a better overview. More information will be released soon...
And here some graphical comparisons between the different chip sizes (all from Olympus):
The Four Thirds type sensor is twice the size of the two thirds type sensor. 18x13.5 mm and diagonal 22.5 mm.
APS format is approx. 24x16 mm and the well known 35mm format is 36x24 mm with a diagonal of 43.3 mm
Olympus is convinced to have found the optimal compromise between size and image quality with this new format. Since it is an open standard, it could really rock, if only enough producers participate. But at the moment only Olympus, Fuji and Kodak are supporting it.
I still do not understand the basis of the 4/3 system. Does it mean 3/4? Surely there are either 3 thirds in something or 4 quarters but not 4 thirds. It is a contradiciton in terms.
I did email Olympus twice but they did not bother to reply which does not do much for my confidence in their customer support. I don't think that they know the answer and I feel that probably it is just a marketing name.
Their literature does not explain it and dealers are unable to help either.
If anyone can help, I would appreciate it.
Happy New Year to everyone.
(follow links "4/3 technology", "the name") they write: "As one may think "Four Thirds" does not refer to the the sensor size. The CCD measures approximately 22.3mm diagonally, not four-thirds of an inch, which would be about 33.9mm. Traditionally, the nominal size of image-sensing devices has been based on a method of calculation that was introduced when vacuum image-sensing tubes were first invented. At the time, the outer diameter of these early 'vidicon' tubes was used to indicate their size. Unfortunately, this convention has remained despite the many advances in imaging technology that have since been made, and so the designation, "a four-thirds-inch sensor," can be a source of confusion. For this reason, many people now prefer to use the word "type" instead of "inch" when discussing the size of digital image sensors. This size was chosen by the Four Thirds design team because it optimally met the different requirements: the need for high image quality and avoiding noise, for accommodating different pixel sizes in the future and allowing the use of a telecentric lens construction."
Thanks for that. I have had a look at the link you gave me. The thing is though that I still don't understand how you can have four thirds when by definition, three thirds make a whole. There is no such thing as four thirds. Four quarters would be another matter.
> There is such a thing as 4/3. If you cut two pies into three equal slices apiece and you take two of the slices, we are left with four thirds -- or 1-1/3 pies. > for most arithmetic, you HAVE to convert numbers like 1-1/3 to a pure fraction.
Mathematics has never been my strong point but although I understand what you say for when two items are involved, it seems to me that you still cannot have four thirds of only one item - such as one camera sensor (?).
From looking at the dates of the post,it looks like it will be a long time to get a answer to this question.
In my e-volt 510 I had 48 images. I had already downloaded these to a disk.
I did not erase but continued to take photos. When i started to review the new shots I got a picture error messages on the photos in the camera. Most of the pictures that did disappear were photos taken in vertical position. Can anyone explain this ? thanks in advance for the help.
> I have heard that editing (deleting) in camera can cause problems. As you take new pictures, camera sees empty slots created by deleting shots and tries to shoehorn pictures into them. Size of picture may not fit, file gets split and corrupted. As far as specifically vertical pictures disappearing, I don't know.