2002-12-08
I read through the link, but did not see anything that
matches your explanation. I noticed that in some places, the term is
described as just a 4/3 system with the word inch missing. In other places
the word inch is added. I just find it strange that the number 4/3 is
the same as the aspect ratio of all non-High Definition TV sets. This is a
ratio and is unit-less. It means for every 4 units in the x direction
there are 3 corresponding units in the y direction. High Definition as
well as movies have a 16:9 aspect ratio.
In fact, see this link below:
I did a Google search and this page popped up. The
first paragraph states emphatically that the 4/3 is an aspect ratio and has
nothing to do with inches at all.
The Four Thirds System
November 1, 2002
In September, Olympus and Kodak announced they were proposing a new digital SLR camera
standard for all digital SLR camera manufacturers to consider. Olympus dubbed it
the Four Thirds System (4/3 System) based on the aspect ratio of the
image sensor proposed. We welcome this new standard and the fact that Olympus is
trying to forge an agreement among the major camera manufacturers to come up
with digital SLR standards.
Because the aspect ratio is expressed as a fraction, and
not as a decimal, it is possible that someone feels it must have inches
attached. Let's end this nonsense that everything conceived somehow had to
be in inches at one time.
You must have received your explanation from the BWMA
site. A known source of bogus information.
John
----- Original Message -----
From: "Markus Kuhn" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[EMAIL PROTECTED]>
Sent: Sunday, 2002-12-08 11:29
Subject: [USMA:23844] Re: New Four Thirds Inch camera
standard
> Olympus/Kodak digital camera optics standard came from.
>
> http://www.dpreview.com/news/0209/02092410olydak43inch.asp
>
> CCD photo sensor chips are traditionally completely metric designs,
> however, they are named after the outer glass tube diameter of an old
> vidicon vacuum-tube image sensor that would have an equivalent imaging
> area. The currently used CCD chips in digital cameras are described in
> data sheets as 2/3-inch sensors, even though no single dimension of the
> chip is actually 2/3-inch, except that they are compatible with optics
> designed for vidicon tubes with 4/3-inch outer glass diameter. The
> vacuum tube industry is still using inch-based designations for glass
> dimensions.
>
> So in a sense, it is a repetition of the story of the 90 mm (3.5 inch)
> floppy disk, a metric design with a historic inch name stuck to it, or
> of the nomencalture for flat pannel displays, which are also still
> widely labelled according to the glass dimensions of cathode-ray tubes
> with equivalent image area.
>
> Markus
>
> --
> Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
> Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
>
