Hello,
I just recently signed up to this forum to ask a question. Hopefully someone
can answer me.
Does anyone know anything about the history of image sensors?
I came across a wikipedia article recently on image sensor format and it had
something there that confused me. Hopefully, someone can help me clear up my
confusion.
Towards the end of the article is a TABLE OF SENSOR SIZES. In the first row of
the table is the type. It is called out by a size in fractional inches.
Except for the 1/4", 1/2" and 1", the rest of these inches I never heard of. I
didn't even know some of the fractions stated were possible. I was always
taught that inches in fractions followed a pattern where the denominator could
only be numbers like 2, 4, 8, 16, 32, and 64.
However, this table has the following fractional inches shown:
1/4", 1/3.6", 1/3.2", 1/3", 1/2.7", 1/2.5", 1/2", 1/1.8", 1/1.7 ", 2/3", 1" and
4/3"
What kind of inch sizes are these and why are they stated in strange fractions
like these? How do you even say such numbers?
I noticed the rest of the article used millimeters to describe the sensor
dimensions. So I was wondering if these strange fractions were meant to be
inch conversions of millimeters. Does anyone know if this is the case?
If you convert all of the inch fractions to millimeters, you get:
6.5, 7.0, 8.0, 8.5, 9.5, 10, 13, 14, 15, 17, 25, and 34.
Of course none of the numbers came out exactly as the numbers I show. I
rounded them to the nearest .5mm. To see if my rounding was biased, I reverse
converted the millimeter numbers and rounded the numbers properly to one
decimal place and was able to get the same fractional numbers shown above.
This lead me to believe that the image sensors were conceived in millimeter
units and later changed to fractional inches. But why? Does anyone know?
Why would someone produce a series of fractional numbers that the average man
can't comprehend when a simpler whole number metric series exists and would
seem to be more functional?
Some of these sensors were based on older model vacuum tubes, such as the 4/3".
But was the 4/3" really a 34mm size? Does anyone know who invented these
tubes and why they chose such strange sizes? Why not a sensible fraction like
1-5/16"?
This strange set of fractional numbers for the sensor types just seems too
strange, so I hoping that someone can provide a logical reason why it was done
that way.
Thank you all in advance for taking your time to provide an answer?
Jerry
