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Re: [OM] 4/3rds, 16Megapixels?

Subject: Re: [OM] 4/3rds, 16Megapixels?
From: Jim Brokaw <jbrokaw@xxxxxxxxxxx>
Date: Thu, 12 Jun 2003 13:54:37 -0700
My understanding was that the 4/3 refers to the 'aspect ratio' of the
sensor... which matches the traditional aspect ratio of video e.g. TV
screens.

The diagonal measurements of TV screens (and computer monitors) was always
stated including some area under the bezel of the cabinet... this changed
for computer monitors when someone won a 'deceptive advertising' suit
against some manufacturer... Now computer monitors at least are all
advertised with a 'true visible area' statement. LCD screens have always
displayed the full advertised measurement.

Aspect ratios are changing for TV due to HD TV which uses a 16:9 ratio (more
like movies). I suppose there is nothing holding any digital camera
manufacturer to any specific aspect ratio, including 3:2, which is the 35mm
film (full-frame) aspect ratio. I expect that 4/3 was chose to better fit
the 'full frame' image onto traditional monitors.

I think 35mm 'half frame' has a 3:4 aspect ratio, so the 4/3 sensor is a
'half frame' image turned to landscape format... In my dreams Olympus will
bring us a digital Pen FT -- that would be just too perfect!

If the 4/3 sensor is much larger physically, there is the possibility of
using larger individual pixel sensor elements, and having more of them as
well. I believe larger pixel sensor elements can be less 'noisy' and may be
less sensitive to dust and to "oblique light rays", a topic Olympus has made
a marketing (if not engineering) issue of before.
-- 

Jim Brokaw
OM-'s of all sorts, and no OM-oney...


on 6/11/03 6:13 PM, k.matsumoto at matsumoto@xxxxxxxxxxxxxxxxxxxxxxxxx
wrote:

>> Andrew and Tom have apparenently misintepreted the 4/3 in the Olydak
>> "4/3 system" as 4/3" (inch) and as meaning the size of the diagonal
>> of the sensor.
> 
> I hear that the size of the sensor is given in the traditional system
> used for vacuum tube type image sensors. The diagonal of the actual,
> effective image capturing area is usually smaller than the nominal
> size description. I cannot explain about the details here, but I think
> I now understand why the screen diagonal of a 18-inch TV is much
> smaller than 18 inches...
> 
> kazuya matsumoto


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