Making sense of the sensor size?

"Neil Harrington" wrote in message
. ..



The 1/1.8 type is about 5.32 x 7.18 mm, and the 1/2.5 type is 4.29 x
5.76 mm.

You can find the *approximate* size of any sensor if you know the actual
focal length of the camera's lens and its 35mm equivalence, both best
taken at the long end of the zoom for the sake of better accuracy.
Dividing the latter by the former will give you the digicam's lens factor.
Dividing the diagonal of a full 35mm frame (about 43.2 mm) by the lens
factor should give you the diagonal of the digicam's sensor. However, this
is a rough method (because the camera lens's stated focal length may not
be precise) and may not give you exactly the figures above.

Expanding on this a little:

Most (but not all) compact digicams have sensors in the 4 : 3 aspect ratio.
This should be convenient for finding the diagonal of the sensor, since it's
the 3-4-5 right triangle familiar if you remember your geometry, i.e. if one
side is 3 units and the adjacent side is 4, the hypotenuse must be 5.

So in the case of the 2/3 type sensor used in my Coolpix 8800 for example,
the 6.6 x 8.8 mm sensor has a diagonal of just 11 mm. A full 35mm frame (24
x 36 mm) has a diagonal of about 43.2 mm, so the lens factor is 43.2 / 11 =
3.927. . . , and multiplying this by the lens's marked focal length (at the
long end) of 89mm, the 35mm equivalence works out to about 349.5mm. This is
close enough to the stated f.l. of 350mm at the long end. This is really
just doing the same math suggested in my previous post, only backwards.

The aspect ratios are different of course, the full-frame 35 being 3 : 2
while the digicam's is 4 : 3. But this doesn't really matter; it's always
the format diagonal that's used in calculations of 35mm equivalence.

Neil

Neil Harrington wrote:
"RPS" wrote in message
...
Could somebody please explain the jargon used to denote the sensor size?
I mean numbers like 1/1.7. How does this translate to actual size
(dimensions or area)?

It actually doesn't translate very well at all, and is a goofy system that
should have been abandoned long ago. The fraction refers to the old video
tube size in inches, which is the way such sensors are traditionally sized
but obviously has nothing to do with digital still cameras.

What is the typical size for DSLR?

Those are not described in that way; only compact cameras use the fractional
inch method. Nikon and some other DSLRs mostly use a sensor of either 23.7 x
15.6 mm or 23.6 x 15.8 mm, in either case roughly the same as the full APS-C
format and often referred to by that term. Most Canon DSLRs s have a
slightly smaller sensor than that, some other makes are smaller still, and a
very few are larger.

For ZLR?
For good P&S?

Both of those types use sensors in the fractional inch sizes, though often
the "inch" is omitted and "type" is substituted. So for example one
manufacturer may call a particular sensor "2/3 inch" and another may call
the same sensor "2/3 type."

Whatever it's called, the 2/3 type is the largest sensor generally found in
any digicam. Its actual size is about 6 x 8 mm.

Other common sizes are 1/1.8 and 1/2.5 -- there are several other sizes as
well, but those appear to be the ones most often used today. I have read of
sensors as small as 1/3.2 but have never owned a digicam with that small a
sensor myself.

In high-end compact cameras of the type you call ZLRs, such as the Nikon
Coolpix 8800, the 2/3 type was common. Most of today's superzoom ZLRs use
much smaller sensors than that, however.

For a very good but more compact camera such as the Nikon P5000, the 1/1.8
type is used and is undoubtedly the best choice. Smaller sensors than that
are more likely to give problems with noise at the higher ISOs, all else
being equal. But where extreme compactness is important it's usual to see
sensors of 1/2.5 type or smaller. Also, many of the superzooms today use
1/2.5 type sensors. It is adequate for most ordinary use.

Camcorders of course have much smaller sensors than these.

Neil


Wouldn't the whole thing make more sense if manufacturers would just
agree to always state the sensor size in sq. millimeters!!!?

Ron Hunter wrote:
Neil Harrington wrote:
"RPS" wrote in message
...
Could somebody please explain the jargon used to denote the sensor size?
I mean numbers like 1/1.7. How does this translate to actual size
(dimensions or area)?

It actually doesn't translate very well at all, and is a goofy system
that should have been abandoned long ago. The fraction refers to the
old video tube size in inches, which is the way such sensors are
traditionally sized but obviously has nothing to do with digital still
cameras.

What is the typical size for DSLR?

Those are not described in that way; only compact cameras use the
fractional inch method. Nikon and some other DSLRs mostly use a sensor
of either 23.7 x 15.6 mm or 23.6 x 15.8 mm, in either case roughly the
same as the full APS-C format and often referred to by that term. Most
Canon DSLRs s have a slightly smaller sensor than that, some other
makes are smaller still, and a very few are larger.

For ZLR?
For good P&S?

Both of those types use sensors in the fractional inch sizes, though
often the "inch" is omitted and "type" is substituted. So for example
one manufacturer may call a particular sensor "2/3 inch" and another
may call the same sensor "2/3 type."

Whatever it's called, the 2/3 type is the largest sensor generally
found in any digicam. Its actual size is about 6 x 8 mm.

Other common sizes are 1/1.8 and 1/2.5 -- there are several other
sizes as well, but those appear to be the ones most often used today.
I have read of sensors as small as 1/3.2 but have never owned a
digicam with that small a sensor myself.

In high-end compact cameras of the type you call ZLRs, such as the
Nikon Coolpix 8800, the 2/3 type was common. Most of today's superzoom
ZLRs use much smaller sensors than that, however.

For a very good but more compact camera such as the Nikon P5000, the
1/1.8 type is used and is undoubtedly the best choice. Smaller sensors
than that are more likely to give problems with noise at the higher
ISOs, all else being equal. But where extreme compactness is important
it's usual to see sensors of 1/2.5 type or smaller. Also, many of the
superzooms today use 1/2.5 type sensors. It is adequate for most
ordinary use.

Camcorders of course have much smaller sensors than these.

Neil


Wouldn't the whole thing make more sense if manufacturers would just
agree to always state the sensor size in sq. millimeters!!!?

Another useful addition would be to state the pixel pitch of the sensor.
This gives an indication of the ultimate light gathering ability of each
pixel on the sensor.
Small pixel pitch = low signal/noise ratio = high noise level in low
light conditions.
For instance, A 10 MP Canon G7, with a 1/1.8" sensor has a smaller pixel
pitch than, say a 5MP Panasonic FZ 20 with a 1/2.5" sensor.
The Canon Sensor itself is larger but its pixel pitch is smaller than
that of the Panasonic sensor.
Bob Williams

"Ron Hunter" wrote in message
...
Neil Harrington wrote:
"RPS" wrote in message
...
Could somebody please explain the jargon used to denote the sensor size?
I mean numbers like 1/1.7. How does this translate to actual size
(dimensions or area)?

It actually doesn't translate very well at all, and is a goofy system
that should have been abandoned long ago. The fraction refers to the old
video tube size in inches, which is the way such sensors are
traditionally sized but obviously has nothing to do with digital still
cameras.

What is the typical size for DSLR?

Those are not described in that way; only compact cameras use the
fractional inch method. Nikon and some other DSLRs mostly use a sensor of
either 23.7 x 15.6 mm or 23.6 x 15.8 mm, in either case roughly the same
as the full APS-C format and often referred to by that term. Most Canon
DSLRs s have a slightly smaller sensor than that, some other makes are
smaller still, and a very few are larger.

For ZLR?
For good P&S?

Both of those types use sensors in the fractional inch sizes, though
often the "inch" is omitted and "type" is substituted. So for example one
manufacturer may call a particular sensor "2/3 inch" and another may call
the same sensor "2/3 type."

Whatever it's called, the 2/3 type is the largest sensor generally found
in any digicam. Its actual size is about 6 x 8 mm.

Other common sizes are 1/1.8 and 1/2.5 -- there are several other sizes
as well, but those appear to be the ones most often used today. I have
read of sensors as small as 1/3.2 but have never owned a digicam with
that small a sensor myself.

In high-end compact cameras of the type you call ZLRs, such as the Nikon
Coolpix 8800, the 2/3 type was common. Most of today's superzoom ZLRs use
much smaller sensors than that, however.

For a very good but more compact camera such as the Nikon P5000, the
1/1.8 type is used and is undoubtedly the best choice. Smaller sensors
than that are more likely to give problems with noise at the higher ISOs,
all else being equal. But where extreme compactness is important it's
usual to see sensors of 1/2.5 type or smaller. Also, many of the
superzooms today use 1/2.5 type sensors. It is adequate for most ordinary
use.

Camcorders of course have much smaller sensors than these.

Neil


Wouldn't the whole thing make more sense if manufacturers would just agree
to always state the sensor size in sq. millimeters!!!?

Almost ANY method of describing sensor size would make a lot more sense than
the one they're using.

Neil

Neil Harrington wrote:
"Ron Hunter" wrote in message
...
Neil Harrington wrote:
"RPS" wrote in message
...
Could somebody please explain the jargon used to denote the sensor size?
I mean numbers like 1/1.7. How does this translate to actual size
(dimensions or area)?
It actually doesn't translate very well at all, and is a goofy system
that should have been abandoned long ago. The fraction refers to the old
video tube size in inches, which is the way such sensors are
traditionally sized but obviously has nothing to do with digital still
cameras.

What is the typical size for DSLR?
Those are not described in that way; only compact cameras use the
fractional inch method. Nikon and some other DSLRs mostly use a sensor of
either 23.7 x 15.6 mm or 23.6 x 15.8 mm, in either case roughly the same
as the full APS-C format and often referred to by that term. Most Canon
DSLRs s have a slightly smaller sensor than that, some other makes are
smaller still, and a very few are larger.

For ZLR?
For good P&S?
Both of those types use sensors in the fractional inch sizes, though
often the "inch" is omitted and "type" is substituted. So for example one
manufacturer may call a particular sensor "2/3 inch" and another may call
the same sensor "2/3 type."

Whatever it's called, the 2/3 type is the largest sensor generally found
in any digicam. Its actual size is about 6 x 8 mm.

Other common sizes are 1/1.8 and 1/2.5 -- there are several other sizes
as well, but those appear to be the ones most often used today. I have
read of sensors as small as 1/3.2 but have never owned a digicam with
that small a sensor myself.

In high-end compact cameras of the type you call ZLRs, such as the Nikon
Coolpix 8800, the 2/3 type was common. Most of today's superzoom ZLRs use
much smaller sensors than that, however.

For a very good but more compact camera such as the Nikon P5000, the
1/1.8 type is used and is undoubtedly the best choice. Smaller sensors
than that are more likely to give problems with noise at the higher ISOs,
all else being equal. But where extreme compactness is important it's
usual to see sensors of 1/2.5 type or smaller. Also, many of the
superzooms today use 1/2.5 type sensors. It is adequate for most ordinary
use.

Camcorders of course have much smaller sensors than these.

Neil


Wouldn't the whole thing make more sense if manufacturers would just agree
to always state the sensor size in sq. millimeters!!!?

Almost ANY method of describing sensor size would make a lot more sense than
the one they're using.

Neil


Pretty much an obvious truth!
One might as well describe it by weight as the current method.

Almost ANY method of describing sensor size would make a lot more sense than
the one they're using.

Neil



You can be sure they want to keep it confusing to the customers by not showing how
small a sensor they are buying, mine is a 1/1.7... (s6000fd) because they want folks in
a "happy buying dillusion" and so happy with what they buy. I did my research, and
it's all I need in a digital, for quality and budget. But that new f50fd has a larger sensor
of 1/1.6... and pocketable... yearn

width: 7.600 / height: 5.700 / diagonal: 9.500 / diameter 14.941 millimeters


xenarshooter

On Tue, 4 Sep 2007 12:53:12 -0700, xenarshooter wrote:

You can be sure they want to keep it confusing to the customers by not
showing how small a sensor they are buying, mine is a 1/1.7... (s6000fd)
because they want folks in a "happy buying dillusion" and so happy
with what they buy. I did my research, and it's all I need in a digital,
for quality and budget. But that new f50fd has a larger sensor of 1/1.6...
and pocketable... yearn

width: 7.600 / height: 5.700 / diagonal: 9.500 / diameter 14.941
millimeters

But how does the number of megapixels compare? If the F50fd has
significantly more than the S6000fd, then the S6000fd has the better
sensor of the two. F50fd == 12mp, S6000fd == 6mp. If you want a
pocketable Fuji, yearn for an F31fd (6mp) or an F40fd (8mp), NOT the
F50fd. The F31fd would probably be the best choice, if you can
still find one.