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Discussion in 'Digital Photography' started by cube, Sep 2, 2006.
Why are sensors called "2/3 inch", etc. if those are not any of their dimensions?
So that we guys will buy bigger lenses to compensate.
Here's a nice article you can/should read about sensors and cropping:
Thanks, but that article doesn't say why these sensors are called like that.
ok. you're not talking about the aspect ratio of the senors are you?
Normal(analog) camera's have a ratio of 2/3 (24*36mm). dSLR have the same
ratio. P&S camera's generally have a 3/4 ratio.http://en.wikipedia.org/wiki/Four_Thirds_System
No, I'm not talking about the aspect ratio. I'm talking about sensors called "1/1.8 inch" and "2/3 inch".
It's not even that. The sensors are specified in different formats, 1/2-inch, 1/3, 1/5 etc. Nominally this is supposed to be the diagonal measurement of the active imaging area, but in real life the active areas are much smaller than that. The number is really to help manufacturers match up lenses with sensors. There is a little table at Micron with typical nominal and actual sizes.
The Micron wording is a bit confusing, but if I understand well they definitely mean that this measure is the size of the image (diameter?) produced by the corresponding lens.
But where does the image end?
The image ends where it ends The effect is what you are probably thinking: the lenses are designed to cover more area than the sensors will see, so some of the potential angle is wasted.
There are painful little formulas and calculators around the net to figure out what you will actually get.
OK, now I understand the original question. And have learned something too!
( I could have asked somebody at work, it work at a company that makes the machines for Micron...)
I suspect it is one of the dimensions, probably the diagonal measurement.
The diagonal is a lot smaller.
Where are you getting your information?
Google "2/3 inch sensor 11mm", for example.
Why are you CCD specs from a manufacturer. Maybe it is the sensor package, the part that needs to be soldered to a board.
But everything for 11mm diagonal always says (2/3 type) wich I would take to be the aspect ratio.
It's not just in CCD specs. It appears in many photo sites.
And many of those google results say "2/3 inch".
Here you have one photo site.
And listing the diagonal of a package would be useless. What people need to know is the width and height.
Does this help?
Or has the answer already been found? I got lost somewhere in the middle of the thread.
Arrr...I was diligently reading through the thread and I knew just where to find the answer, but you beat me to it.
That link just goes to a general area.
Here's the real explanation; it's more outdated crap bogging us down (like interlace and 29.97 FPS):
"Sensors are often referred to with a "type" designation using imperial fractions such as 1/1.8" or 2/3" which are larger than the actual sensor diameters. The type designation harks back to a set of standard sizes given to TV camera tubes in the 50's. These sizes were typically 1/2", 2/3" etc. The size designation does not define the diagonal of the sensor area but rather the outer diameter of the long glass envelope of the tube. Engineers soon discovered that for various reasons the usable area of this imaging plane was approximately two thirds of the designated size. This designation has clearly stuck (although it should have been thrown out long ago). There appears to be no specific mathematical relationship between the diameter of the imaging circle and the sensor size, although it is always roughly two thirds."
This thread is from 4 years ago. In case you didn't notice.