Is sensor size measured diagonally?

[Jothi]

35 mm, 1 inch, four thirds, 1/2.3, 1/1.2....... .. Are they the diagonal lengths of the sensors?

 

[peterharvey]

Sensor sizes measured by width by height eg 36 mm by 24 mm.

Televisions and computers are measured by the diagonal.

 

[Jothi]

So is it the height that is shown by 1 inch, four thirds, 35 mm, 1/2.3 and 1/1.2?

 

[LynniePad]

So is it the height that is shown by 1 inch, four thirds, 35 mm, 1/2.3 and 1/1.2?

No, those "Inch" designations have very little to do with the sensor dimensions. They are related to the size of the glass envelope that contains the sensor in TV applications.

Here's an article that includes a list; the diagonal measurement have little to do with reality.

https://en.wikipedia.org/wiki/Image_sensor_format

Camera manufacturers use the confusing descriptions to misrepresent the actual sensor size.

 

[Bobby49]

Just to make it thoroughly confusing, what we call 35mm film size has a frame that is 24mmx36mm.

 

[chuxter]

Welcome to the confusing world of sensor sizes! You will run into many different terms:

• 35mm
• FF
• Crop-sensor
• 1/3.75"
• MF
• FX and DX
• APS-C
• APS-H

Many of us think the marketing socket-heads at the various camera companies do this on purpose to confuse customers. "A confused customer is an easy mark!"

Customers don't help; they are all too willing in many instances to just parrot what the "experts" say [it makes them sound in-the-know]. And the various magazines and websites are generally not in the business of controlling the language we use. They just want to please both the readers and the advertisers, so they don't get involved.

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

For MANY years, we did rather well. All camera sizes were things like 8" x 10", 4" x 5", 2.25" x 3.25", 2.25" x 2.25", etc. There were also metric sizes, like 6 x 7 cm.

Then we started naming the sizes for the "container" that held the image; like 8mm, 16mm, 35mm, and 50mm film used in movie cameras. And when video cameras first appeared, we "sized" the Vidicon tubes used in them by stating the outer diameter of the glass envelope [which was larger and pretty much unrelated to the size of the photo-sensitive scanned area]. That VERY confusing scheme was used when we invented Silicon sensors for video cameras.

When 35mm film [used in movie cameras] was "borrowed" to use in still cameras, the inventor, Oskar Barnack, turned the film sideways and sorta doubled the frame size to the 24 x 36mm size we still use today and call "Full-Frame" or "FF". BUT it is really a double frame if you understand the history.

Until we can get EVERYONE to simply use the X and Y dimensions of the sensors we have in our cameras, it will eternally be confusing.

There ARE resources on the Internet that help decode the myriad of sensor size nomenclature, so remember: "Google is your friend!"

 

[Mark B.]

35 mm, 1 inch, four thirds, 1/2.3, 1/1.2....... .. Are they the diagonal lengths of the sensors?

For no good reason at all, manufacturers have standardized on an archaic engineering standard carried over from the early days of picture tubes. It's explained on this DPR page.

Mark

 

[six34sigma]

35 mm, 1 inch, four thirds, 1/2.3, 1/1.2....... .. Are they the diagonal lengths of the sensors?

Here is a link to sensor size and the relative crop factors:

http://ricehigh.blogspot.com/2011/08/sensor-sizes-re-visited-including.html

 

[Gerry Winterbourne]

Welcome to the confusing world of sensor sizes! Many of us think the marketing socket-heads at the various camera companies do this on purpose to confuse customers. "A confused customer is an easy mark!"

And many don't think that. The terminology has developed organically, with different usages following in succession. Each of those usages had a good reason for coming into use. As soon as the second came along the first was (by the simple logic of wanting everything the same) outdated and redundant, so the first should have been superseded by the second.

But then the third was different so the renamed first (to match second) and second ones should have been superseded by the third. And so on ... Think of the sweat of renaming everything that had gone before; and that wouldn't have reduced confusion because everything made earlier would still have its original label so we'd still need to understand all the terms anyway.

Trying to blame all this on the makers is naïve and/or paranoid.

You will run into many different terms:

• 35mm
• FF
• Crop-sensor
• 1/3.75"
• MF
• FX and DX
• APS-C
• APS-H

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

On the other hand, the diagonal is an easy way to compare the relative sizes of different sensors. There are, of course, cameras with different aspect ratios and it's useful to know. Consider my Pentax Q with sensor 6.17 x 4.55 mm. I know it's 4:3, of course, but it's not immediately apparent from the stated dimensions. If we are to go to a new system I'd much prefer 7.6mm (4:3) as a description.

For MANY years, we did rather well. All camera sizes were things like 8" x 10", 4" x 5", 2.25" x 3.25", 2.25" x 2.25", etc. There were also metric sizes, like 6 x 7 cm.

In fact it's not so much that the sizes were different but that two systems were used to name them.

Then we started naming the sizes for the "container" that held the image; like 8mm, 16mm, 35mm, and 50mm film used in movie cameras. And when video cameras first appeared, we "sized" the Vidicon tubes used in them by stating the outer diameter of the glass envelope [which was larger and pretty much unrelated to the size of the photo-sensitive scanned area]. That VERY confusing scheme was used when we invented Silicon sensors for video cameras.

When 35mm film [used in movie cameras] was "borrowed" to use in still cameras, the inventor, Oskar Barnack, turned the film sideways and sorta doubled the frame size to the 24 x 36mm size we still use today and call "Full-Frame" or "FF". BUT it is really a double frame if you understand the history.

Not really. It's true that the 3:2 35mm film format was devised by using twice the number of perforations for a horizontally run film as was used (in a different medium) for vertically run film. But 35mm stills framing was never really linked to 35mm cine framing.

The origin of FF as presently used comes from the fact that early digital sensors were so expensive that the ones used in DSLRs were smaller than the 36x24mm frame of SLRs. Even the users who understood the reason still would have preferred to use the lenses they already owned (and which gave different results on their DSLRs) to display the full frame size they had been made for. Describing DSLRs as "full frame" is no more than a way of telling customers that they can use their lenses to display the full frame size they had been made for.

Until we can get EVERYONE to simply use the X and Y dimensions of the sensors we have in our cameras, it will eternally be confusing.

And, for many people, X and Y will be confusing.

 

[Klaus dk]

Just to make it thoroughly confusing, what we call 35mm film size has a frame that is 24mmx36mm.

35mm film is 35mm wide. For stills, it is also known as 135 film. Most 135 film cameras expose a frame of 24 x 36mm, but there were also 24 x 24mm and 18 x 24mm frame cameras.

Kodak Instamatic 126 film is also 35mm wide, but has only one registration hole per 28 x 28mm frame.

I don't believe in all these conspiration theories about salespeople trying to confuse customers. If you really care, you'll find out; if you don't care, no matter how clear the information available to you is, you will not learn.

Of all the nations in the world, only three has not yet gone metric. Which ones? Liberia, Myanmar and the USA.

 

[chuxter]

Welcome to the confusing world of sensor sizes! Many of us think the marketing socket-heads at the various camera companies do this on purpose to confuse customers. "A confused customer is an easy mark!"

And many don't think that. The terminology has developed organically, with different usages following in succession. Each of those usages had a good reason for coming into use. As soon as the second came along the first was (by the simple logic of wanting everything the same) outdated and redundant, so the first should have been superseded by the second.

But then the third was different so the renamed first (to match second) and second ones should have been superseded by the third. And so on ... Think of the sweat of renaming everything that had gone before; and that wouldn't have reduced confusion because everything made earlier would still have its original label so we'd still need to understand all the terms anyway.

Trying to blame all this on the makers is naïve and/or paranoid.

You imply that there are only two possibilities: Naive and paranoid. I prefer "insightful".

You will run into many different terms:

• 35mm
• FF
• Crop-sensor
• 1/3.75"
• MF
• FX and DX
• APS-C
• APS-H

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

On the other hand, the diagonal is an easy way to compare the relative sizes of different sensors. There are, of course, cameras with different aspect ratios and it's useful to know. Consider my Pentax Q with sensor 6.17 x 4.55 mm. I know it's 4:3, of course, but it's not immediately apparent from the stated dimensions. If we are to go to a new system I'd much prefer 7.6mm (4:3) as a description.

With HS math, any kid can find the aspect ratio [just divide X by Y]. Of course that gives numbers like 1.333 or 1.5. With a college degree, we know how to get 4:3 or 3:2. ;-)

Finding the diagonal definitely takes a PHD. The diagonal is the square-root of X-squared plus Y-squared.

7.6mm (4:3) is OK, but 6.17 x 4.55mm is better. Why hide the REAL dimensions? If you give 7.6mm (4:3) to an average person, they will be unable to figure out the ACTUAL dimensions of the rectangle!

For MANY years, we did rather well. All camera sizes were things like 8" x 10", 4" x 5", 2.25" x 3.25", 2.25" x 2.25", etc. There were also metric sizes, like 6 x 7 cm.

In fact it's not so much that the sizes were different but that two systems were used to name them.

Huh? What two systems? The list above your remark uses only one system!

Then we started naming the sizes for the "container" that held the image; like 8mm, 16mm, 35mm, and 50mm film used in movie cameras. And when video cameras first appeared, we "sized" the Vidicon tubes used in them by stating the outer diameter of the glass envelope [which was larger and pretty much unrelated to the size of the photo-sensitive scanned area]. That VERY confusing scheme was used when we invented Silicon sensors for video cameras.

When 35mm film [used in movie cameras] was "borrowed" to use in still cameras, the inventor, Oskar Barnack, turned the film sideways and sorta doubled the frame size to the 24 x 36mm size we still use today and call "Full-Frame" or "FF". BUT it is really a double frame if you understand the history.

Not really. It's true that the 3:2 35mm film format was devised by using twice the number of perforations for a horizontally run film as was used (in a different medium) for vertically run film. But 35mm stills framing was never really linked to 35mm cine framing.

There were a few still cameras that took a "half-frame" image on 135 film, mostly in the 1960's. They had a 24 x 18mm format.

You might want to read: https://en.wikipedia.org/wiki/35_mm_film#Common_formats

I describes the many different 35mm film formats. They varied from 24.89 x 18.67 mm to 20.32 x 15.24mm to 21.84 x 20.83mm. They danced around the 22 x 16mm format.

The origin of FF as presently used comes from the fact that early digital sensors were so expensive that the ones used in DSLRs were smaller than the 36x24mm frame of SLRs. Even the users who understood the reason still would have preferred to use the lenses they already owned (and which gave different results on their DSLRs) to display the full frame size they had been made for. Describing DSLRs as "full frame" is no more than a way of telling customers that they can use their lenses to display the full frame size they had been made for.

Simple but confusing.

Until we can get EVERYONE to simply use the X and Y dimensions of the sensors we have in our cameras, it will eternally be confusing.

And, for many people, X and Y will be confusing.

No more confusing that a 4' x 8' sheet of plywood or 2x4 lumber! You want to have customers go to Home Depot and ask for a sheet of 8.944 foot plywood? ;-)

 

[LynniePad]

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

And, for many people, X and Y will be confusing.

And this is not confusing?

The Fujifilm X20 has a 2/3-inch (8.8mm by 6.6mm) sensor while the Canon G1 X has a 1.5-inch sensor (18.7mm by 14mm).

(Taken at random from a site discussing sensor sizes).

One of my older cameras is described as having a 1/2.5" sensor. That's a rather odd number format, and a reasonable person might assume that some manipulation of that silly fraction might reveal the dimension of one side of the sensor, but he'd be wrong.

If manufacturers don't actively conspire to have confusing nomenclature, they also don't go out of their way to inform the consumer. Marketing departments are not known for their honesty; haven't you noticed out-dated equipment labelled as the "Classic" model, or buggy hardware and software marketed as the "Pro" version?

Each field has its own special nomenclature to impress the masses. I recall explaining the basis of Chemistry's pH scale to an old guy who'd been puzzling over it for years; he went away satisfied, muttering something about "The inverse power of the hydrogen".

Then there's the Richter scale, invariably described in the media as "The open-ended Richter scale", despite the fact that R15 corresponds to the total destruction of the Earth.

 

[Gerry Winterbourne]

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

And, for many people, X and Y will be confusing.

And this is not confusing?

The Fujifilm X20 has a 2/3-inch (8.8mm by 6.6mm) sensor while the Canon G1 X has a 1.5-inch sensor (18.7mm by 14mm).

I didn't say it wasn't; that's a straw man argument.

My point is that whatever system one chooses it will confuse someone.

 

[Gerry Winterbourne]

Welcome to the confusing world of sensor sizes! Many of us think the marketing socket-heads at the various camera companies do this on purpose to confuse customers. "A confused customer is an easy mark!"

And many don't think that. The terminology has developed organically, with different usages following in succession. Each of those usages had a good reason for coming into use. As soon as the second came along the first was (by the simple logic of wanting everything the same) outdated and redundant, so the first should have been superseded by the second.

But then the third was different so the renamed first (to match second) and second ones should have been superseded by the third. And so on ... Think of the sweat of renaming everything that had gone before; and that wouldn't have reduced confusion because everything made earlier would still have its original label so we'd still need to understand all the terms anyway.

Trying to blame all this on the makers is naïve and/or paranoid.

You imply that there are only two possibilities: Naive and paranoid. I prefer "insightful".

No, I didn't imply it - I said it. You may prefer insightful but that preference doesn't make it right.

You will run into many different terms:

• 35mm
• FF
• Crop-sensor
• 1/3.75"
• MF
• FX and DX
• APS-C
• APS-H

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

On the other hand, the diagonal is an easy way to compare the relative sizes of different sensors. There are, of course, cameras with different aspect ratios and it's useful to know. Consider my Pentax Q with sensor 6.17 x 4.55 mm. I know it's 4:3, of course, but it's not immediately apparent from the stated dimensions. If we are to go to a new system I'd much prefer 7.6mm (4:3) as a description.

With HS math, any kid can find the aspect ratio [just divide X by Y]. Of course that gives numbers like 1.333 or 1.5. With a college degree, we know how to get 4:3 or 3:2. ;-)

Of course. But dividing 6.17 by 4.55 is quite a lengthy process to do accurately and mentally.

Finding the diagonal definitely takes a PHD. The diagonal is the square-root of X-squared plus Y-squared.

I don't need to find the diagonal: we are discussing a naming convention so I'll be told the diagonal.

7.6mm (4:3) is OK, but 6.17 x 4.55mm is better. Why hide the REAL dimensions? If you give 7.6mm (4:3) to an average person, they will be unable to figure out the ACTUAL dimensions of the rectangle!

Why is it better? Why do I need to know the sides of a sensor? If we are talking about ease of comparing sensor sizes one dimension is easier than two. For image circle purposes (comparative focal lengths) it's the diagonal that matters. It's much easier to compare 43mm (3:2) to 7.6mm (4:3) than it is to compare 36x24mm to 6.17x4.55mm.

For MANY years, we did rather well. All camera sizes were things like 8" x 10", 4" x 5", 2.25" x 3.25", 2.25" x 2.25", etc. There were also metric sizes, like 6 x 7 cm.

In fact it's not so much that the sizes were different but that two systems were used to name them.

Huh? What two systems? The list above your remark uses only one system!

Inch system and metric system.

Then we started naming the sizes for the "container" that held the image; like 8mm, 16mm, 35mm, and 50mm film used in movie cameras. And when video cameras first appeared, we "sized" the Vidicon tubes used in them by stating the outer diameter of the glass envelope [which was larger and pretty much unrelated to the size of the photo-sensitive scanned area]. That VERY confusing scheme was used when we invented Silicon sensors for video cameras.

When 35mm film [used in movie cameras] was "borrowed" to use in still cameras, the inventor, Oskar Barnack, turned the film sideways and sorta doubled the frame size to the 24 x 36mm size we still use today and call "Full-Frame" or "FF". BUT it is really a double frame if you understand the history.

Not really. It's true that the 3:2 35mm film format was devised by using twice the number of perforations for a horizontally run film as was used (in a different medium) for vertically run film. But 35mm stills framing was never really linked to 35mm cine framing.

There were a few still cameras that took a "half-frame" image on 135 film, mostly in the 1960's. They had a 24 x 18mm format.

You might want to read: https://en.wikipedia.org/wiki/35_mm_film#Common_formats

It describes the many different 35mm film formats. They varied from 24.89 x 18.67 mm to 20.32 x 15.24mm to 21.84 x 20.83mm. They danced around the 22 x 16mm format.

I'm familiar with the Wiki article. I can't see what any of that has to do with my paragraph above it.

The origin of FF as presently used comes from the fact that early digital sensors were so expensive that the ones used in DSLRs were smaller than the 36x24mm frame of SLRs. Even the users who understood the reason still would have preferred to use the lenses they already owned (and which gave different results on their DSLRs) to display the full frame size they had been made for. Describing DSLRs as "full frame" is no more than a way of telling customers that they can use their lenses to display the full frame size they had been made for.

Simple but confusing.

In what was is it confusing?

Until we can get EVERYONE to simply use the X and Y dimensions of the sensors we have in our cameras, it will eternally be confusing.

And, for many people, X and Y will be confusing.

No more confusing that a 4' x 8' sheet of plywood or 2x4 lumber! You want to have customers go to Home Depot and ask for a sheet of 8.944 foot plywood? ;-)

Well, you've hit the nail on the head. For large things like sheets of ply simple, round numbers are adopted for convenience. Ditto for the old 5x4" etc film/plate sizes.

But when we get into decimal fractions (especially with two or more places) it's not so easy. Your 8.944' is comparable in that way to 6.17mm and that's why I don't like your suggestion for sensor sizes.

Similarly, it's easy to see a 4x8' has an aspect ratio of 2; fairly easy to see that 36x24mm is 3:2; downright obscure that 6.17x4.55mm is 4:3.

 

[chuxter]

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

And, for many people, X and Y will be confusing.

And this is not confusing?

The Fujifilm X20 has a 2/3-inch (8.8mm by 6.6mm) sensor while the Canon G1 X has a 1.5-inch sensor (18.7mm by 14mm).

Yes, that is confusing, but it is not what either Gerry or I suggest.

I would rewrite it thusly:

The Fujifilm X20 has a 8.8mm by 6.6mm sensor while the Canon G1 X has a 18.7mm by 14mm sensor.

I think Gerry would rewrite it like this:

The Fujifilm X20 has a 11mm [4:3] sensor while the Canon G1 X has a 23.36mm [4:3] sensor.

Correct me if I'm wrong.

 

[LynniePad]

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

And, for many people, X and Y will be confusing.

And this is not confusing?

The Fujifilm X20 has a 2/3-inch (8.8mm by 6.6mm) sensor while the Canon G1 X has a 1.5-inch sensor (18.7mm by 14mm).

Yes, that is confusing, but it is not what either Gerry or I suggest.

I would rewrite it thusly:

The Fujifilm X20 has a 8.8mm by 6.6mm sensor while the Canon G1 X has a 18.7mm by 14mm sensor.

I was simply pointing out that the "Inch" designations are completely unhelpful unless you are in the know.

Since we are all familiar with the pixel numbers such as 6000x4000, it's only logical to stick to actual sensor dimensions.

Diagonal dimensions are only of interest if you want to refer to the diameter of the image circle, perhaps as a way of normalising for different aspect ratios.

 

[chuxter]

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

And, for many people, X and Y will be confusing.

And this is not confusing?

The Fujifilm X20 has a 2/3-inch (8.8mm by 6.6mm) sensor while the Canon G1 X has a 1.5-inch sensor (18.7mm by 14mm).

Yes, that is confusing, but it is not what either Gerry or I suggest.

I would rewrite it thusly:

The Fujifilm X20 has a 8.8mm by 6.6mm sensor while the Canon G1 X has a 18.7mm by 14mm sensor.

I was simply pointing out that the "Inch" designations are completely unhelpful unless you are in the know.

Since we are all familiar with the pixel numbers such as 6000x4000, it's only logical to stick to actual sensor dimensions.

We are in agreement.

Diagonal dimensions are only of interest if you want to refer to the diameter of the image circle, perhaps as a way of normalising for different aspect ratios.

I think the diagonal is of academic interest only. It does not inform about anything useful, IMO.

If we have to do something simple that sorta applies across many aspect ratios, then perhaps we should state the PRODUCT of X*Y; the AREA? The problem with only stating the AREA is that it does not inform about the aspect ratio. There is a BIG difference between the usability of a 1:1 and a 16:9 aspect ratio.

I still think that simply stating the X-Y dimensions of the sensors in mm is best.

 

[chuxter]

Welcome to the confusing world of sensor sizes! Many of us think the marketing socket-heads at the various camera companies do this on purpose to confuse customers. "A confused customer is an easy mark!"

And many don't think that. The terminology has developed organically, with different usages following in succession. Each of those usages had a good reason for coming into use. As soon as the second came along the first was (by the simple logic of wanting everything the same) outdated and redundant, so the first should have been superseded by the second.

But then the third was different so the renamed first (to match second) and second ones should have been superseded by the third. And so on ... Think of the sweat of renaming everything that had gone before; and that wouldn't have reduced confusion because everything made earlier would still have its original label so we'd still need to understand all the terms anyway.

Trying to blame all this on the makers is naïve and/or paranoid.

You imply that there are only two possibilities: Naive and paranoid. I prefer "insightful".

No, I didn't imply it - I said it. You may prefer insightful but that preference doesn't make it right.

You will run into many different terms:

• 35mm
• FF
• Crop-sensor
• 1/3.75"
• MF
• FX and DX
• APS-C
• APS-H

There is only one way to properly describe the size of a rectangular object: Give the two dimensions, the X and Y values. A diagonal dimension also requires the aspect ratio; this is too complicated for many people to understand.

On the other hand, the diagonal is an easy way to compare the relative sizes of different sensors. There are, of course, cameras with different aspect ratios and it's useful to know. Consider my Pentax Q with sensor 6.17 x 4.55 mm. I know it's 4:3, of course, but it's not immediately apparent from the stated dimensions. If we are to go to a new system I'd much prefer 7.6mm (4:3) as a description.

With HS math, any kid can find the aspect ratio [just divide X by Y]. Of course that gives numbers like 1.333 or 1.5. With a college degree, we know how to get 4:3 or 3:2. ;-)

Of course. But dividing 6.17 by 4.55 is quite a lengthy process to do accurately and mentally.

Finding the diagonal definitely takes a PHD. The diagonal is the square-root of X-squared plus Y-squared.

I don't need to find the diagonal: we are discussing a naming convention so I'll be told the diagonal.

7.6mm (4:3) is OK, but 6.17 x 4.55mm is better. Why hide the REAL dimensions? If you give 7.6mm (4:3) to an average person, they will be unable to figure out the ACTUAL dimensions of the rectangle!

Why is it better? Why do I need to know the sides of a sensor? If we are talking about ease of comparing sensor sizes one dimension is easier than two. For image circle purposes (comparative focal lengths) it's the diagonal that matters. It's much easier to compare 43mm (3:2) to 7.6mm (4:3) than it is to compare 36x24mm to 6.17x4.55mm.

For MANY years, we did rather well. All camera sizes were things like 8" x 10", 4" x 5", 2.25" x 3.25", 2.25" x 2.25", etc. There were also metric sizes, like 6 x 7 cm.

In fact it's not so much that the sizes were different but that two systems were used to name them.

Huh? What two systems? The list above your remark uses only one system!

Inch system and metric system.

I know that we call it the Metric System. There are "systems" other than units. For example a system of referencing the size of a rectangular object by stating it's X and Y dimensions. In THAT sense, the above uses ONE system.

If you were referring to the strange "system" of describing the sensor by reference to the outer diameter of a mythical, nonexistent glass vacuum tube in inches and then parenthetically giving either the X+Y or Diagonal in mm, that makes sense and I agree w/ you.

Then we started naming the sizes for the "container" that held the image; like 8mm, 16mm, 35mm, and 50mm film used in movie cameras. And when video cameras first appeared, we "sized" the Vidicon tubes used in them by stating the outer diameter of the glass envelope [which was larger and pretty much unrelated to the size of the photo-sensitive scanned area]. That VERY confusing scheme was used when we invented Silicon sensors for video cameras.

When 35mm film [used in movie cameras] was "borrowed" to use in still cameras, the inventor, Oskar Barnack, turned the film sideways and sorta doubled the frame size to the 24 x 36mm size we still use today and call "Full-Frame" or "FF". BUT it is really a double frame if you understand the history.

Not really. It's true that the 3:2 35mm film format was devised by using twice the number of perforations for a horizontally run film as was used (in a different medium) for vertically run film. But 35mm stills framing was never really linked to 35mm cine framing.

There were a few still cameras that took a "half-frame" image on 135 film, mostly in the 1960's. They had a 24 x 18mm format.

You might want to read: https://en.wikipedia.org/wiki/35_mm_film#Common_formats

It describes the many different 35mm film formats. They varied from 24.89 x 18.67 mm to 20.32 x 15.24mm to 21.84 x 20.83mm. They danced around the 22 x 16mm format.

I'm familiar with the Wiki article. I can't see what any of that has to do with my paragraph above it.

You said, "But 35mm stills framing was never really linked to 35mm cine framing." That is because there was never ONE cine framing to use as a reference. That is precisely why I said Oskar "sorta" doubled the frame size. :-0

The origin of FF as presently used comes from the fact that early digital sensors were so expensive that the ones used in DSLRs were smaller than the 36x24mm frame of SLRs. Even the users who understood the reason still would have preferred to use the lenses they already owned (and which gave different results on their DSLRs) to display the full frame size they had been made for. Describing DSLRs as "full frame" is no more than a way of telling customers that they can use their lenses to display the full frame size they had been made for.

Simple but confusing.

In what was is it confusing?

I think "FF" mostly refers to the sensor, not the lens. I simply got confused when I read that paragraph; therefore, it must be confusing. ;-)

Until we can get EVERYONE to simply use the X and Y dimensions of the sensors we have in our cameras, it will eternally be confusing.

And, for many people, X and Y will be confusing.

No more confusing that a 4' x 8' sheet of plywood or 2x4 lumber! You want to have customers go to Home Depot and ask for a sheet of 8.944 foot plywood? ;-)

Well, you've hit the nail on the head. For large things like sheets of ply simple, round numbers are adopted for convenience. Ditto for the old 5x4" etc film/plate sizes.

But when we get into decimal fractions (especially with two or more places) it's not so easy.

I never suggested how many decimal places should be used. It's OK to do some rounding for the masses. Like a 2x4 is not actually 2" x 4"; it's 1.5" x 3.5". Everyone knows that after the first time they buy one and measure it!

Your 8.944' is comparable in that way to 6.17mm and that's why I don't like your suggestion for sensor sizes.

Similarly, it's easy to see a 4x8' has an aspect ratio of 2; fairly easy to see that 36x24mm is 3:2; downright obscure that 6.17x4.55mm is 4:3.

This may have to do with education. People my age don't have difficulty dividing 6.17 by 4.55 and getting 1.333...then writing that as 1 + 1/3 and then simplifying it to 4/3. You may not have gotten as good an education as we did? ;-)

 

[Jothi]

Oh! guys.. it seems like you all running off the track...

Plz can you tell me what are measured diagonally and what are measured vertically ? (the sensor sizes [if possible, all of 'em] )

thanks...

 

[Gerry Winterbourne]

For MANY years, we did rather well. All camera sizes were things like 8" x 10", 4" x 5", 2.25" x 3.25", 2.25" x 2.25", etc. There were also metric sizes, like 6 x 7 cm.

In fact it's not so much that the sizes were different but that two systems were used to name them.

Huh? What two systems? The list above your remark uses only one system!

Inch system and metric system.

I know that we call it the Metric System. There are "systems" other than units. For example a system of referencing the size of a rectangular object by stating it's X and Y dimensions. In THAT sense, the above uses ONE system.

You used inches and cm. Those units are part of what are commonly called "inch" (or "Imperial") and "metric" systems. While there are plenty of other systems and naming conventions you used only those two, and those are the two I identified in my reply ...

If you were referring to the strange "system" of describing the sensor by reference to the outer diameter of a mythical, nonexistent glass vacuum tube ...

... so I can't imagine why you'd bring this into the discussion of that paragraph.

The origin of FF as presently used comes from the fact that early digital sensors were so expensive that the ones used in DSLRs were smaller than the 36x24mm frame of SLRs. Even the users who understood the reason still would have preferred to use the lenses they already owned (and which gave different results on their DSLRs) to display the full frame size they had been made for. Describing DSLRs as "full frame" is no more than a way of telling customers that they can use their lenses to display the full frame size they had been made for.

Simple but confusing.

In what was is it confusing?

I think "FF" mostly refers to the sensor, not the lens.

Of course it does, and that's what I said: a FF sensor allows people to use lenses the way the lenses were intended rather than with restricted FOV.

Until we can get EVERYONE to simply use the X and Y dimensions of the sensors we have in our cameras, it will eternally be confusing.

And, for many people, X and Y will be confusing.

No more confusing that a 4' x 8' sheet of plywood or 2x4 lumber! You want to have customers go to Home Depot and ask for a sheet of 8.944 foot plywood? ;-)

Well, you've hit the nail on the head. For large things like sheets of ply simple, round numbers are adopted for convenience. Ditto for the old 5x4" etc film/plate sizes.

But when we get into decimal fractions (especially with two or more places) it's not so easy.

I never suggested how many decimal places should be used.

How is writing something to three places of decimals not sugestive of that?

It's OK to do some rounding for the masses. Like a 2x4 is not actually 2" x 4"; it's 1.5" x 3.5". Everyone knows that after the first time they buy one and measure it!

Your 8.944' is comparable in that way to 6.17mm and that's why I don't like your suggestion for sensor sizes.

Similarly, it's easy to see a 4x8' has an aspect ratio of 2; fairly easy to see that 36x24mm is 3:2; downright obscure that 6.17x4.55mm is 4:3.

This may have to do with education. People my age don't have difficulty dividing 6.17 by 4.55 and getting 1.333...then writing that as 1 + 1/3 and then simplifying it to 4/3.

Please escribe the full process you'd use, step by step.

You may not have gotten as good an education as we did? ;-)

Probably better, as the answer isn't actually 1.333... but 1.35604...

--
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Gerry
___________________________________________
First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
[email protected]