Is There Anything Better Than '35mm equivalent'?

When I'm looking at digital camera lenses, I always have to fall back on the old crutch of what is the 35mm equivalent.

In 35mm, I know what the view of a 50mm lens is, and I know what view angle that 50mm lens would give you if it were 2 1/4 film square format or if it were 2 1/4 x 2 3/4 format.

Since digital cameras have different sized sensors, I am lost without the 35mm equivalent. Will there ever be a different yardstick?

What do young photographers do if they've grown up without ever using a film camera?

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http://Dos-Ojos.smugmug.com/gallery/1230755/1/57652842

dos ojos said:

Since digital cameras have different sized sensors, I am lost without the 35mm equivalent. Will there ever be a different yardstick?

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Probably not even more obvious is the fact different sensor sizes 4/3 2x crop APS-C (1.5/1.6x Sigma 1.7x) APS-H 1.3x

Then we have a load of various smaller sized sensors in compacts/superzoom/bridge type models.

Hard to get a standard when there isn't one!

dos ojos said:

What do young photographers do if they've grown up without ever using a film camera?

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Learn it the same as everyone else ;-)

You'll find a lot of thread about this, but I am afraid there won't be an alternative in the near future... I have been using 35 mm and 6 x 6 film cameras, so that's not a problem for me.

My purely academic proposal would be to start with a function of the diagonal of the sensor (for 35mm that would be nearer to 45mm than 50...)

People are already accustomed to the range of zooms : 4x, 6x ... and now 20x or more.

It would become :* x0.5 to x6* for my small Panasonic TZ6. It shows a big x12 under its lens.
I must be dreaming

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Michel B

Binoculars have always used a magnification such as 7x (350mm equivalent in 35mm +or -), giving the magnification when compared to the human eye (quite inexact I'd say). That's different to (and as confusing as) a lens range of 7x, which is the multiple of the widest angle on a given lens to its highest focal length.

Angle of view in degrees of width has been looked at also. "Hey is that the new 108 to 6 degree lens I read about?" Yikes!

003tvd said:

Binoculars have always used a magnification such as 7x (350mm equivalent in 35mm +or -), giving the magnification when compared to the human eye (quite inexact I'd say). That's different to (and as confusing as) a lens range of 7x, which is the multiple of the widest angle on a given lens to its highest focal length.

Angle of view in degrees of width has been looked at also. "Hey is that the new 108 to 6 degree lens I read about?" Yikes!

Click to expand...

I think new users are interested in the xXX factor. It's not only a marketing thing. It's really helpful. It's a simple and coherent ratio.

Not sure they are accustomed to the idea of a 'normal' field of view like old film users. However, it would be simple to imagine :
x0.5 is wide angle
x0.75 semi wide angle
x1 normal
x2 to x3 portrait
x4 to x6 tele photo
more super telephoto

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Michel B

I suspect that it is only us geeks who think in terms of 35mm lenses... the average joe Is much more conversant with the 2x, 3x, 8x type of thing ala binos....

Peeps are always coming up to me and saying... "oooh.. thats a big lens you must be able to see Uranus" (Or some other equally difficult thing to see..) only to then be met by the inevitable bored expression when I explain it is only the equivilant of a 6x zoom (or whatever) and that it is so big to let in lots of light......

--
http://www.pageonephotography.co.uk
Striving hard to be the man that my dog thinks I am.

I think manufacturers will use a 35mm equivalent as "standard" for the foreseeable future. Hope so, anyway.

Otherwise everyone would be at sea trying to figure out what the heck a camera does. Right now it's pretty easy to figure out a 1.3 or 1.6 crop factor.

NottsPhoto said:

Peeps are always coming up to me and saying... "oooh.. thats a big lens you must be able to see Uranus"

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I suppose it might not be appropriate to respond, "turn around, bend over; and I will see if I can see Ur-anus" ???

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

MichelB said:

003tvd said:

Binoculars have always used a magnification such as 7x (350mm equivalent in 35mm +or -), giving the magnification when compared to the human eye (quite inexact I'd say). That's different to (and as confusing as) a lens range of 7x, which is the multiple of the widest angle on a given lens to its highest focal length.

Angle of view in degrees of width has been looked at also. "Hey is that the new 108 to 6 degree lens I read about?" Yikes!

Click to expand...

I think new users are interested in the xXX factor. It's not only a marketing thing. It's really helpful. It's a simple and coherent ratio.

Not sure they are accustomed to the idea of a 'normal' field of view like old film users. However, it would be simple to imagine :
x0.5 is wide angle
x0.75 semi wide angle
x1 normal
x2 to x3 portrait
x4 to x6 tele photo
more super telephoto

Click to expand...

I totally support something like this -- at least for P&S cameras with non-interchangeable lenses.

35mm equilvalent means nothing if you are not and old film user. (albeit the rebirth of FF does put more validity to it continued use)

And just the total zoom range means absolutely nothing knowing the starting wide-angle; (but then that must again be expressed in 35mm equivalent so you are back to the original problem).

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

JoePhoto said:

35mm equilvalent means nothing if you are not and old film user.

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As another poster above already pointed out, 35mm equivalent means the same thing to everyone who takes the time to learn it. Every hobby has vocabulary/terminology to learn, and even in this age of digital cameras, the books on digital photography I've read explain focal length in terms of 35mm equivalent. My newest camera (S200EXR) has 35mm equivalent settings marked on the zoom ring. As one of the many online tutorials a person can access says, "By using the 35mm equivalent, we simply make it more convenient for everyone to use a handy reference point." http://www.photoxels.com/tutorial_focal_length.html

The thing that most people are interested in is - What is the field of view? For that purpose the angular FOV spec is best. Of the angular specs the radian spec is more convenient than degrees to use due to the simple relationship between object distance and linear FOV.

linear FOV = R X D where D is distance from the camera lens to the object & R is in radians(unitless).

For example, say a camera/sensor has a 55mm lens and FOV of 0.2Vert. x 0.4Horz. radians. What linear FOV is covered at 10 meters from the camera?

linear FOV Vert. = 10 m. X 0.2 = 2m
linear FOV Horz. = 10 m. X 0.4 = 4m

Change the lens to a 110 mm and you would half the FOVs.

The camera's sensor size & lens determines the FOV.

For a given camera spec the lens focal length and the radian FOV for horizontal and vertical. For example,

XYZ Camera, 45 mm lens, 0.2V x 0.3H

If you don't like decimal numbers you can use milliradians, 200V X 300H.

(Forget 35mm equivalent. The only reason that the "35 mm equivalent" is around is because that film size dominated use and the sensor size for 35 mm film was the exposed area, 24 mm V X 36 mm H. They are approximately matching the new sensors to the 35mm film's FOVs for given focal length lenses and the 24 mm V X 36mm H format)

Chas Tennis

Chas Tennis said:

The thing that most people are interested in is - What is the field of view? For that purpose the angular FOV spec is best.

Click to expand...

Absolute focal length is solely a property of the lens. But angular field of view depends both on the sensor size and on the lens. This means that when you move a lens from a full-frame body to an APS-C body, the angular field of view range will change -- just like the 35mm-equivalent "focal lengths" do.

Barry Fitzgerald said:

Member said:

What do young photographers do if they've grown up without ever using a film camera?

Click to expand...

Learn it the same as everyone else ;-)

Click to expand...

Anyone mystified by "Horse Power?"
(Well, maybe we are, but we use it)

Dave

Tom_N said:

Chas Tennis said:

The thing that most people are interested in is - What is the field of view? For that purpose the angular FOV spec is best.

Click to expand...

Absolute focal length is solely a property of the lens. But angular field of view depends both on the sensor size and on the lens. This means that when you move a lens from a full-frame body to an APS-C body, the angular field of view range will change -- just like the 35mm-equivalent "focal lengths" do.

Click to expand...

I believe that the FOV in radians for all lenses and all sensors is simply:

Sensor dimension,mm Horiz / Lens FL,mm = FOV Horiz in radians.

Sensor dimension, mm Vert / Lens FL,mm = FOV Vert in radians.

To get linear fields of view multiply FOV in radians by distance to object.

I wish that sensors were specified in mmV X mmH instead of 1/2.3" which I have not looked up and still can't understand.

Chas Tennis

003tvd said:

Binoculars have always used a magnification such as 7x (350mm equivalent in 35mm +or -), giving the magnification when compared to the human eye (quite inexact I'd say). That's different to (and as confusing as) a lens range of 7x, which is the multiple of the widest angle on a given lens to its highest focal length.

Click to expand...

No, this isn't about magnification, it's about coverage, or field of view. Binocular manufacturers specify coverage in meters per 1000 metres, feet per thousand yards, or degrees. (Binoculars of the same magnification can have different fields of view).

It's different to cameras because the image is projected directly onto your retina, allowing a magnification to have meaning. With cameras, the image isn't viewed directly on the sensor, but on a screen or a print of a different size, so magnifications don't necessarily have meaning.

The binocular field of view measurement would be suitable, as you mentioned:

003tvd said:

Angle of view in degrees of width has been looked at also. "Hey is that the new 108 to 6 degree lens I read about?" Yikes!

Click to expand...

IF you are going to use a "magnification" factor to classify lenses, can someone please define what "x1" magnification means? Similarly, 10x magnification means ten times in relation to what?

OTOH in terms of angle of view, this is fairly easily applied and understood at wide-angle, so a 120 degree ange of view is really wide and 60 degrees somewhere near "normal", but if I'm looking for a telephoto lens (say for wildlife photography) do I need a 6 degree AOV or would I be better off with 4.5 degrees?
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Chas Tennis said:

Photographers feel guilty that all they do for a living is press a button. - Andy Warhol

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telephotos should be measured by moon diameters along the long edge. So a 1000mm lens would be described as a (I'm guessing this bit) 2MD lens.

Wide angles should be measured by the movement of the sun, so a 180 fisheye would be a 12 hour lens.

I'm putting sticky labels with the new names on my lenses right now.

cheers
Flakey

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flakey

MisterBG said:

IF you are going to use a "magnification" factor to classify lenses, can someone please define what "x1" magnification means? Similarly, 10x magnification means ten times in relation to what?

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This is still only going to apply to non-interchangeable lens P&S's, but I suggest that 1X be where the mm of the lens equals the "diagonal" of the sensor.

(sorry) Retreating back to 35mm equivanlent for purposes of illustration. A 35mm x 24mm FF sensor gives a diagonal of about 42mm. Well, it so happens that 42mm is a "normal" lens for 35mm. 6x6 (Hasselblad) 120mm cameras (2 1/4 x 2 1/4 = 60mm x 60mm) = 84mm "normal" lens.

So 1X is easy, simply the diagonal of the sensor. From there it is easy direct multiplication/division to arrive at 2X, 3X, 5X, 10X0. (A 420mm would be 10X and 840mm would be 20X with FF camera)

Conversely a 21mm (wide-angle) would be .5X -- (35mm equals .83X).

All referenced back to "normal" mm ... (diagonal of sensor).

Since 7x / 10x "power" are currently used for binoculars, most people are already familar.

But; The best part of this is that the differential between telephoto and wide-angle is IMMEDIATELY apparent by the "decimal points" for anything wider than normal.

BG454 said:

OTOH in terms of angle of view, this is fairly easily applied and understood at wide-angle, so a 120 degree ange of view is really wide and 60 degrees somewhere near "normal", but if I'm looking for a telephoto lens (say for wildlife photography) do I need a 6 degree AOV or would I be better off with 4.5 degrees?

Click to expand...

Their are two problems with AOV / FOV

1.) Most people don't have any idea what angles mean.

2.) It is still not immediately discernable where the "normal" break is between wide-angle and telephoto.

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

After 30+ years of dealing with consumers, training retail staff, and teaching photography courses, the most common question centers around magnification (how much closer will the subject appear in my photo, when compared to my eye?). AOV in degrees is difficult for most consumers to wrap brain cells around. Our approaches may be from different directions, as most of my dealings are with Mr & Mrs average snapshooter, not so much with the esteemed contributors of this forum. But it is a perspective for the manufacturers to keep in mind, to whom are their products aimed at in the marketplace.

conversely, binocs with different magnifications can have the same FOV.l