Proposing a simple shorthand for writing "35mm equivalent field of view"

Started Feb 6, 2013 | Discussions
rossdoyle Regular Member • Posts: 128
Proposing a simple shorthand for writing "35mm equivalent field of view"
5

We are long overdue for a shorthand way of describing lens/sensor equivalent field of view.

We now have a profusion of sensor sizes and lenses to go with those sensors, and adaptors to cross mounts, and now even Speed Boosters to direct more light to a sensor after the lens. But “What does the camera see?” is the important question to understand how to use these instruments. We have managed to get by, saying “35mm equivalent field of view” in various ways over and over and re-explaining when this question comes up.

On this forum and elsewhere we continually see arguments occur when a commenter or magazine article writer or camera advertisement will assume that everyone knows what they mean and will say, “This 200mm APS-C lens gives you 300mm.” Some people, despite understanding perfectly well the writer’s intent, find this egregious disregard of physics unacceptable, and need to point out the writer or commenter has no idea of what they’re talking about, and that 300mm focal length is always 300mm, and that the sensor crops the image. Whether necessary or not, this discussion is inserted just about everywhere.

There is an easy way to stop the confusion and continual re-explanation – let’ just agree on a simple shorthand convention. My proposal is to write, “[X]mme” to mean “[X]mm equivalent field of view on a 35mm format camera.” Thus in the example above, the writer could day “This 300mm APS-C gives you 450mme.” As another example, we won’t have to get indignant when a small sensor point-and-shoot with a 4.3mm lens is advertised as having a “24mm Wide-Angle Lens,” if they would instead say, “24mme Wide-Angle Lens.” When talking about APS-C cameras, Four Thirds cameras, Pentax Q, large format cameras, point-and-shoots of any sensor size, camera phones, Speed Boosters, and so on, this shorthand will similarly help. Is this something we can do?

chris_uk
chris_uk Contributing Member • Posts: 762
Re: Proposing a simple shorthand for writing "35mm equivalent field of view"

35mm FOV

scorrpio
scorrpio Veteran Member • Posts: 3,595
Re: Proposing a simple shorthand for writing "35mm equivalent field of view"
1

rossdoyle wrote:

We are long overdue for a shorthand way of describing lens/sensor equivalent field of view.

Are we?   I've seen shorthands already, like '24mm eq', or '24mm (35)' or '24mm FF', though none of these amounted to a standard.   The real use of this 'equivalent' is for the shoppers comparing various cameras.   As these are often not well versed in jargon, stores like B&H tend to simply spell it out.   " 35mm Equivalent Focal Length" is a whole lot easier to Google than 'mme'.

Is this something we can do?

If by 'we' you mean 'DPReview forum members', and by 'this' you mean establishing an industry-wide standard, the answer is a fairly firm 'no'.   If you could get hold of Canon or Nikon head of marketing, and persuade them that 'mme' will look better and more clear to the average Joe than '35mm equivalent' in their product brochures, then you might have a chance.

John1940
John1940 Senior Member • Posts: 2,727
A different approach

rossdoyle wrote:

We are long overdue for a shorthand way of describing lens/sensor equivalent field of view.

We now have a profusion of sensor sizes and lenses to go with those sensors, and adaptors to cross mounts, and now even Speed Boosters to direct more light to a sensor after the lens. But “What does the camera see?” is the important question to understand how to use these instruments. We have managed to get by, saying “35mm equivalent field of view” in various ways over and over and re-explaining when this question comes up.

On this forum and elsewhere we continually see arguments occur when a commenter or magazine article writer or camera advertisement will assume that everyone knows what they mean and will say, “This 200mm APS-C lens gives you 300mm.” Some people, despite understanding perfectly well the writer’s intent, find this egregious disregard of physics unacceptable, and need to point out the writer or commenter has no idea of what they’re talking about, and that 300mm focal length is always 300mm, and that the sensor crops the image. Whether necessary or not, this discussion is inserted just about everywhere.

There is an easy way to stop the confusion and continual re-explanation – let’ just agree on a simple shorthand convention. My proposal is to write, “[X]mme” to mean “[X]mm equivalent field of view on a 35mm format camera.” Thus in the example above, the writer could day “This 300mm APS-C gives you 450mme.” As another example, we won’t have to get indignant when a small sensor point-and-shoot with a 4.3mm lens is advertised as having a “24mm Wide-Angle Lens,” if they would instead say, “24mme Wide-Angle Lens.” When talking about APS-C cameras, Four Thirds cameras, Pentax Q, large format cameras, point-and-shoots of any sensor size, camera phones, Speed Boosters, and so on, this shorthand will similarly help. Is this something we can do?

First, let me say that I don't have any financial relationship with the company that produces the Dragon dictation software. I started using it a couple of years ago because it makes it much easier for me to compose letters and other documents.

One of the interesting things that I found out in using the program is that I can sometimes dictate long phrases or clauses much faster than anybody could type them. I can also train Dragon to print out the short form by dictating the long form. Somewhat surprisingly, that can be very useful if I'm talking about numbers and units.

Conversely, I can use the short form, such as you are proposing, and have it type out the long form. There is no particular length limitation to what the long form is. And, since I usually talk into Microsoft Word or PowerPoint all of the spelling comes out correctly. There are times when Dragon makes an error if I don't speak clearly or have not taken enough time for it to get used to my pronunciation.

There are several grades of Dragon starting with something that is pretty inexpensive and going to what doctors and hospitals use. I obviously do not use the medical version but if I worked in a hospital and had something to do with drugs it would sure come in handy.

There are verbal commands for almost everything that you can do with the keyboard, but it's hard to remember all of them. However, the user can just stop dictating and make any corrections the same way as using Microsoft Word. If you need to clear your throat or if you're going to be talking to somebody else all you have to do is press the hot button, which is usually the + key. If you don't have a numeric keypad, you can change the hotkey to whatever you want. It takes a while to not have a hot microphone if you start talking to somebody else or start laughing.

Your proposal makes a lot of sense but I hate more acronyms. There's a big advantage in being more verbose because almost everybody can talk faster than they can type.

John1940

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Joseph S Wisniewski Forum Pro • Posts: 34,130
non madam

rossdoyle wrote:

We are long overdue for a shorthand way of describing lens/sensor equivalent field of view.

We now have a profusion of sensor sizes and lenses to go with those sensors, and adaptors to cross mounts, and now even Speed Boosters to direct more light to a sensor after the lens. But “What does the camera see?” is the important question to understand how to use these instruments. We have managed to get by, saying “35mm equivalent field of view” in various ways over and over and re-explaining when this question comes up.

On this forum and elsewhere we continually see arguments occur when a commenter or magazine article writer or camera advertisement will assume that everyone knows what they mean and will say, “This 200mm APS-C lens gives you 300mm.” Some people, despite understanding perfectly well the writer’s intent, find this egregious disregard of physics unacceptable, and need to point out the writer or commenter has no idea of what they’re talking about, and that 300mm focal length is always 300mm, and that the sensor crops the image. Whether necessary or not, this discussion is inserted just about everywhere.

There is an easy way to stop the confusion and continual re-explanation – let’ just agree on a simple shorthand convention. My proposal is to write, “[X]mme” to mean

Madam X. Literally.

comprenez-vous?

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Ron Poelman
Ron Poelman Veteran Member • Posts: 6,319
It's all back to front really .....

what we have here, is an input loss, not some resulting gain in focal length.
It should be expressed as a percentage utilised vs "available"
If a sensor is in the way of 80% of the incoming field
then that is its rating - 80%; and the inevitable cropping multiplier follows.
This will matter when RAW goes circular !

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Deleted1929 Forum Pro • Posts: 13,050
A solution to a non-problem, IMO (nt)
1
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StephenG

Dan Marchant Senior Member • Posts: 2,863
"Irrelevant" is the shorthand phrase your looking for. (n/t)
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hjulenissen Senior Member • Posts: 2,106
Why make it so hard? Degrees describe what is relevant to photography...

What is the main consern for casual users? My guess is "how many people can I cram into this lense before crashing into the wall", or "how small a bird can I shoot at 30m distance".

With that in mind, I suggest "22 degrees field of view on a m43 sensor". That should be the photographers way of describing a lense (might upset phycisists though).

-h

24hrexposure Regular Member • Posts: 297
Re: Proposing a simple shorthand for writing "35mm equivalent field of view"

I don't see the problem.  If you know what sensor you're using, you only need to know the true focal length and aperture of the lens to know how it will perform.  If you always use m4/3 cameras, what's the point of converting back and forth between 'ff equivalent' and true specs?  You'll quickly learn how a 7mm or a 25mm lens looks on YOUR camera, and that's the only thing that matters.

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dosdan Contributing Member • Posts: 522
Re: Why make it so hard? Degrees describe what is relevant to photography...

hjulenissen wrote:

With that in mind, I suggest "22 degrees field of view on a m43 sensor".

But, that's not FOV you're referring to. (FOV uses a distance value, e.g. 23m, which describes the field height/width/diagonal).

You're referring to the AOV (Angle-Of-View).

Dan

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Joseph S Wisniewski Forum Pro • Posts: 34,130
Trig is harder than similiar triangles...
1

hjulenissen wrote:

What is the main consern for casual users? My guess is "how many people can I cram into this lense before crashing into the wall", or "how small a bird can I shoot at 30m distance".

With that in mind, I suggest "22 degrees field of view on a m43 sensor". That should be the photographers way of describing a lense (might upset phycisists though).

Well, you can describe a "lense" however you like.

As far as a "lens", well, you've managed to pick a measure that will upset pretty much everyone. "Hold on kids, while daddy goes and gets his protractor". We won't even get into the whole diagonal FOV vs. horizontal FOV vs. vertical FOV thing. For four thirds, of course, it's got to be diagonal, because Panasonic has constant diagonal 22.5mm on 16:9, 3:2, and 4:3, and they're pretty much in charge of four thirds these days.

Focal length is a lot easier, either for the casual users or the "phycisists" [sic] because it's not a trigonometric relationship, no one has to work math to deal with it. Similar triangles has worked for a century and a half of photography.

It will also upset marketing people, because the bigger, more expensive lens gets the smaller number.

It will upset most interchangeable lens camera users, because Canon, Nikon, and Sony all make cameras in both APS and FF, and that means you need two degrees scales on a zoom.

The thing that makes the most sense is good old kyd (know your diagonal), which lets you do similar triangles or "magnification" ratios easily. It's so simple that anyone who can actually manage to spell lens can do it.

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John1940
John1940 Senior Member • Posts: 2,727
Re: Proposing a simple shorthand for writing "35mm equivalent field of view"

24hrexposure wrote:

I don't see the problem. If you know what sensor you're using, you only need to know the true focal length and aperture of the lens to know how it will perform. If you always use m4/3 cameras, what's the point of converting back and forth between 'ff equivalent' and true specs? You'll quickly learn how a 7mm or a 25mm lens looks on YOUR camera, and that's the only thing that matters.

What if I use several types of camcorders, P&S cameras and APS-C DSLRs and have used FF SLRs for 50 years? It's extremely useful to have an approximate standard in one's head for FF angle of view.

I don't remember the angle for any camera. But, I do remember what a 16 mm, 24 mm, 28 mm, 35 mm, 50 mm, 80 mm, 100 mm, 200 mm, 300 mm, and 400 mm (in FF terms) is used for.

I also know how to creat a spreadsheet cribsheet in short order to show the FF 35 mm equivalent horizontal AOV for any camera or camcorder I have (or any that exists). The same cribsheet can use any focal length input and sensor shape. Just enter the numbers. This is Spreadsheet 101 stuff.

Don't clutter your brain with angles. Just remember the FF equivalent lens focal lengths and their uses. The 35 mm FF numbers won't change for a long time because that format offers the best balance for very high IQ, performance and cost. (It does not mean that FF is better for travel photography for a non-pro such as me. I use APS-C, a G15, and sometimes a camcorder. And the cribsheet.)

John1940

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BertIverson Veteran Member • Posts: 3,811
Agree: a simple shorthand for writing "35mm equivalent field of view"
1

Good idea. However, good luck with your mission. I like XXmme because I generally have used XXmm Eq. (mostly when discussing P&S cameras)
You get my vote.
Bert

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pavi1 Veteran Member • Posts: 6,861
Re: Proposing a simple shorthand for writing "35mm equivalent field of view"

Too late, the cat is already out of the bag.

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hjulenissen Senior Member • Posts: 2,106
Re: Trig is harder than similiar triangles...

Joseph S Wisniewski wrote:

Focal length is a lot easier, either for the casual users or the "phycisists" [sic] because it's not a trigonometric relationship, no one has to work math to deal with it. Similar triangles has worked for a century and a half of photography.

Most people who use cameras today do not employ math. Why would they have to if their lense was a "x-to-y degrees" lens instead of a "X-to-Y mm" lens?

It will also upset marketing people, because the bigger, more expensive lens gets the smaller number.

I do not care much about marketing peoples opinion. Are you saying that it is hard to sell wide-angles because they are "10-20mm" instead of "17-50mm"?

It will upset most interchangeable lens camera users, because Canon, Nikon, and Sony all make cameras in both APS and FF, and that means you need two degrees scales on a zoom.

Since they have gotten rid of some other scales, it seems that they have room for this. Luckily (?) degrees are the same all over world (I hope there is no such thing as "metric" degrees?)

It's so simple that anyone who can actually manage to spell lens can do it.

In my native tongue, it is actually spelled "objektiv". "Linse" means a single piece of glass.

-h

hjulenissen Senior Member • Posts: 2,106
Re: Proposing a simple shorthand for writing "35mm equivalent field of view"

24hrexposure wrote:

I don't see the problem.

The incredible amount of text and discussions about it suggests that it is a problem, at least to some.

I know people who stay away from DSLR photography until they can get the focal length numbers right (i.e. until digital FF is cheap enough that numbers are like they remember them from the 70s).

-h

dosdan Contributing Member • Posts: 522
Re: Trig is harder than similiar triangles...

hjulenissen wrote:

Joseph S Wisniewski wrote:

Focal length is a lot easier, either for the casual users or the "phycisists" [sic] because it's not a trigonometric relationship, no one has to work math to deal with it. Similar triangles has worked for a century and a half of photography.

Most people who use cameras today do not employ math. Why would they have to if their lense was a "x-to-y degrees" lens instead of a "X-to-Y mm" lens?

It will also upset marketing people, because the bigger, more expensive lens gets the smaller number.

I do not care much about marketing peoples opinion. Are you saying that it is hard to sell wide-angles because they are "10-20mm" instead of "17-50mm"?

It will upset most interchangeable lens camera users, because Canon, Nikon, and Sony all make cameras in both APS and FF, and that means you need two degrees scales on a zoom.

Since they have gotten rid of some other scales, it seems that they have room for this. Luckily (?) degrees are the same all over world (I hope there is no such thing as "metric" degrees?)

It's so simple that anyone who can actually manage to spell lens can do it.

In my native tongue, it is actually spelled "objektiv". "Linse" means a single piece of glass.

-h

They have: 400 gon (or grad) = 360 degrees.

The military use mils. In Australia, it is 6400 mils = 360 degrees.  I think it's the same in NATO and in the US. But the Russians are different: 6000 mils = 360 degrees.

http://en.wikipedia.org/wiki/Degree_%28angle%29#Alternative_units

Dan.

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john farrar
john farrar Veteran Member • Posts: 5,038
Re: Proposing a simple shorthand for writing "35mm equivalent field of view"

pavi1 wrote:

Too late, the cat is already out of the bag.

And it's stalking the birds.

Given that thousands of 35mm sensor-equipped cameras are used by pros and becoming more accessible in terms of price to enthusiasts, do we actually need to change the convention?

mme wasn't a bad idea though...

Detail Man
Detail Man Forum Pro • Posts: 16,789
[X]meme ...

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