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[OM] Re: Super 4/3?

Subject: [OM] Re: Super 4/3?
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxx>
Date: Mon, 20 Mar 2006 06:12:58 -0500
I knew about the arcane measurements of Vidicon tubes but thought I 
could trust an official Oly document on the size of the image circle for 
the 4/3 mount.  But you are right.  Despite text that says:
-----------------------------------------
(TECHNICAL NOTE: The fraction noted in these sensors refers to the 
diameter of the projected Image Circle, and not the diagonal diameter of 
the Image Sensor. The projected Image Circle from the E-1 system works 
out to be 1 and 1/3 inches, or more elegantly, "Four Thirds". See Figure 
2 below.)
-----------------------------------------
If you actually refer to "Figure 2 below" you will see that the image 
circle is larger than but not much larger than the diagonal of the 
sensor.  I'm sure I couldn't find the reference but I recall reading 
somewhere long ago that the 4/3 standard had an image circle large 
enough to to support a square image format the size of the long image of 
the current sensors.  If true, that would make it about 25.5mm.

Chuck Norcutt



Moose wrote:

> Chuck Norcutt wrote:
> 
>>This Oly page states that the 4/3 in the specification refers to the 
>>size of the image circle which is four thirds of an inch or 1-1/3 inches 
>>  or 33.8mm.
>><http://olympusdigitalschool.com/e-system_cameras/e-1/E-1_Digital_Camera_-_A_Closer_Look/index.html>
>>
>>The E-1 only uses 21.6mm of that.
>><http://www.olympus-europa.com/consumer/dslr_7045.htm>
>>  
> 
> Sorry to be late on this thread, but there is some significant 
> misinformation that should be corrected, in case it's still rattling 
> around in someone(s) head(s).
> 
> The 4/3" figure refers to a now really arcane measurement of the size of 
> video sensing tubes. The actual usable area is considerable smaller. 
> Here's a more detailed explanation 
> <http://www.dpreview.com/learn/?/Glossary/Camera_System/sensor_sizes_01.htm>.
> 
> Moose
> 
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