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Issues when determining camera Sensor Size for Calculations

In the days of using film, there were maybe a dozen film sizes popular enough to contend with, but today, there must be hundreds or more different digital cameras, past and present, using many different sensor sizes, so it's difficult to keep straight which is which by camera model name, most of which I never heard of. The calculators on my site do not even attempt deciphering camera model, they only want to know sensor size. I call it versatility, works with any camera. 😊 And it couldn’t help to try to go by camera model, because for the most part, compact and phone camera manufacturers simply don’t tell us the sensor size. It would be great if the camera manufacturers did show sensor size in the specifications of their camera models, but for the most part, they don't (except mainly for cameras with interchangeable lenses, like DSLRs).

The camera sensor size is all important with respect to the degree of enlarging of its image to viewing size, which affects the use of these calculators and their uses:

All of these calculations must know and use sensor size. There are a few issues complicating determination of correct camera sensor size, and this page tries to summarize those sensor size issues with a little more detail.

Cameras with interchangeable lenses (like DSLR) seem pretty good about specifying the actual sensor size in the specifications (sensor W×H in mm). That's great, if you know it, then use it. But compacts and especially cell phones are most mysterious of all. Why they cannot simply specify sensor size is the mystery to me. But there might sometimes be a clue, detailed below.

Concepts of computing sensor size

The importance of the sensor size is that it frames (crops) the lens image size, to determine the field of view from the lens. Crop Factor (as the term is popularly used) is just a standard of comparison of the ratio of the 35 mm film diagonal to our sensor's diagonal (sensor size). The point of knowing crop factor is that for those of us familiar with the Fields of View for various focal lengths on 35 mm film (and very many of us became very familiar with 35 mm film), then we know how to predict the field of view seen by the various sizes of the new digital cameras introduced to us. But if you are not familiar with using 35 mm film, then Crop Factor may not have much meaning for you.

Except also however, if we know Crop Factor and Aspect Ratio for our camera, then we can compute our sensor size. And we must know sensor size for computing Depth of Field or Field of View of our cameras.

35 mm Equivalent Focal Length is just Crop Factor × Actual focal length on our camera. The Equivalent focal length is used on the 35 mm film camera (NOT on our camera), but if we find lens specs for a 35 mm Equivalent focal length that will match the field of view of our camera, then we know Crop Factor, and then also our sensor size.

So all of this is just the simplest direct math, no magic. However, specs for all of the numbers (Crop Factor and focal length and aspect ratio and megapixels) are normally all rounded numbers, very likely only two significant digits, which is slightly counter-productive to precision of computing, but is probably pretty close, close enough for most uses, and is vastly better than knowing nothing.

Specs for compact cameras and cell phone cameras seem unlikely to ever mention any actual sensor size, but knowing it is still all important to be able to do any calculations with it. Discussion of discovering that sensor size is much of the subject on this page.

Summary of ways to find necessary sensor size data

Sensor size specifically meaning sensor Width × Height, in mm.
• Cameras with interchangeable lenses (including DSLR cameras): Best case, these typically actually do tell us all the important information we might need. You could say that the calculators are intended for them. The manufacturers camera spec (in user manual and online) normally should show sensor size in mm directly (specify it in calculator Option 1). If size is not shown, Crop Factor may be mentioned (can use that calculator Option then), but it is a rounded number, normally only two significant digits. The lens spec (or often the image Exif) probably shows Equivalent focal length, which can be used to compute Crop Factor. The lens used might be a zoom lens or not (which can otherwise make the search for Equivalent focal length be comparable to the methods here for a cell phone or a compact camera). The image Exif data will show focal length used for the picture (see Steps below).
• Cell phone cameras: Worst case. Lots of luck with calculations, as cell phones tell us almost no essential information about the camera. With few exceptions, no sensor size, no sensor type (most are CCD), no crop factor, and fewer are telling us focal length. Those web sites that do may well be telling it wrong. My observation intended as a warning about web sites showing phone focal lengths is that it seems too common to see phone camera specs showing a focal length like maybe about 24 or 27 mm. That is simply impossible and misleading. Phone camera sensor sizes necessarily must instead have normal lens focal lengths typically closer to around 4 mm, more or less, it varies a little with sensor size, which we don't know either. However focal length is often incorrectly shown (internet web sites) to instead be maybe 24 to 27 mm, which is in fact the Equivalent Focal Length, which is Not the real focal length, except some sites incorrectly do call it focal length. But Equivalent Focal length in fact applies to an entirely different camera, specifically a hypothetical full frame 35 mm film camera, simply comparing fields of view of the two cameras. Equivalent Focal Length ABSOLUTELY DOES NOT MEAN this camera has that actual or effective focal length... regardless if some web site specs do show that anyway. The Field of View is equivalent, NOT the focal lengths. It means a 35 mm film camera with that focal length sees the same size field of view that this camera sees with its own actual lens (normally around 4 mm focal length for phone cameras).

The image Exif data should show the actual Focal Length of your camera, and some Exif may also show Equivalent Focal Length for 35 mm film format (at least iPhone Exif has shown it, but these two numbers are probably not located adjacently in the Exif). The Exif data comes directly from the camera manufacturer, very likely correct, so don’t discount this source. The calculators have an Equivalent Focal Length option which if the Equivalent and actual real focal length are known, can compute sensor size. Not all cell phones show Exif containing Equivalent Focal Length however. Cell phones don't zoom, but some newer models do have multiple cameras with different lenses and sensors (wide angle and telephoto) for the rear camera (don't confuse it with the front camera).

But the Samsung site appears to at least offer the 1/xx inch number for the sensor size (see below).

• If cell phones or compacts might mention a 1/xx inch sensor size, it may not be an exact precise number, but that Wikipedia chart mentioned below) may be a big help to determine sensor size.
• Compact cameras: The image Exif data shows zoom focal length used for the picture. Also the manufacturers lens spec (in user manual and online product advertising, and often in the image Exif data) should show specs for the Minimum and Maximum Focal Length, and the corresponding Equivalent Focal Length, as described in the examples below. These two values are probably not located adjacently in the Exif, you should search a little. These two values are a spec number of the zoom lens, not necessarily the zoom focal length that you actually just used for your picture. The calculator Equivalent Option will compute sensor size from this.

A caution: For zoom lenses, the Focal Length when zoomed is reported in Exif. The lens zooms continuously, but the reported value is the nearest of only several relatively coarse discrete steps, which is not necessarily exactly the precise actual (this is mentioned at Steps below). The Equivalent specs do this measuring using either end of the optical zoom range, where the actual focal length is known more accurately.

• A caution: A Pixel Size method will probably Not be accurate enough. The sensor specs may show Pixel Size in μm (micrometers, also called microns). For example, 1.25 μ (10-6 meter) is 0.00125 mm (10-3 meter). And the specs show megapixels, from which with aspect ratio, you can compute image dimensions in pixels, but megapixels and aspect ratio are rounded, so it won't necessarily be exact. However, you can get actual exact pixel dimensions from one of your images. And then Pixels of width × Pixel Size may seem an obvious method, but it won't be exact sensor width, because the pixels are slightly smaller than the spacing of the pixels (spacing is called pitch, there is a bit of space between pixels).

The point is, these are often ways to determine the focal length and sensor size numbers required to use the calculator. DSLR cameras are easiest, but compact cameras are pretty easy too. However many cell phone cameras can be very difficult to learn sensor size. Finding sensor size is the purpose of this page below.

Generalized 1/xx inch sensor sizes

Smaller cameras, notably phones and compacts, often offer sensor size numbers like for example 1/2.3 inch (and there are many other values of these numbers). But these "1/xx inch" sensor numbers are Not fully meaningful. The "1/x inch" description is just a "name", and is NOT the sensor dimension, the number is Not even related to the sensor.

This video tube example is from the Wikipedia article.
It's a false specification (seems much like fraud when continued today) that compares the sensor to the picture size of an old video tube in early television industry days (before CCD, maybe from the 1950s to about the 1980s (many years ago), perhaps a useful comparison back then, but no longer of importance today... today TV is also using digital sensors too.)

The "1/xx inch" dimension was that outer diameter of the glass vacuum tube, and absolutely nothing about the digital sensor is that dimension (the sensor diagonal of the tube is probably no more than 2/3 of that dimension). Video tubes have not been used for more than 30 years, semiconductor CCD is used today). It's just an inflated false number for digital sensors (this number simply does NOT exist on a digital sensor). A so-called One Inch digital sensor measures only 13.2 × 8.8 mm, and the diagonal is barely 0.62 inch. Calling it one inch does sound larger, but nothing on it is one inch. But if we know how to approximately convert it, it is better than no information at all.

The most useful thing to know about this 1/xx" number is that there is a Wikipedia chart that offers a conversion of many of these 1/x inch numbers to usable W×H mm values, so there is some hope of determining sensor size. But there can be several different sensors claiming the same 1/xx number, so it can be less than exactly precise. Nevertheless, small phone and compact cameras like to specify sensor size this way (if at all), instead of specifying the actual sensor W×H size in mm.

Note that this Wikipedia chart does not show Aspect Ratio. The dedicated chips and film will vary, but realize that most of the 1/xx inch chips shown are 4:3 chips. Divide Width by Height to verify aspect ratio so you know what the numbers shown are.

There are few more of these video tube conversion charts online. I don't know where they get their numbers, but they all seem to vary slightly. A few different digital sensors could round to the same tube number, but not all those chips are necessarily actually the same size. It is just a nominal number shown instead of any precise value. Television cameras may have been a major CCD customer in the early days, but why the chip manufacturers continue to use this nomenclature today is a mystery to me. Even television has not used the video tubes in maybe 35 years. The obvious correct specification is the actual sensor dimensions in mm... which has meaning, and could be used for Field of View and Depth of Field and other computed purposes.

Instead, any correct calculation using sensor size really needs the correct sensor size, actual W×H in mm. An accurate Crop factor can compute that. Using Crop Factor will be rounded but correct, and determining the crop factor from the lens Effective Focal Length spec should be correct. Even these specs are rounded, so not amazingly precise, but close enough, likely within 1%.

Computing Sensor Size from Crop Factor

If you know the sensor dimensions, great, use them, that's what it's about, problem solved. But otherwise, knowing accurate Crop Factor is the next best method to determine sensor size. Crop factor is defined by sensor size, so we can easily determine the sensor dimensions from the sensor crop factor (which computing dimensions also need to know the correct Aspect Ratio of the sensor chip).

The 35 mm film size was very popular, well known to very many older photographers, and is used now as the standard comparison of sensor size today. When they hear about 24 mm focal length, they immediately think of quite wide angle (on 35 mm film). However, on most of these new-fangled tiny digital sensors, that would be strong telephoto (so also hearing Equivalent helps greatly). Crop Factor is computed from the sensor size comparison to 35 mm film, and it is simply the ratio of the diagonal of a 35 mm film frame to the diagonal of another sensor frame diagonal.

Crop Factor =

Diagonal dimension of 35 mm film
Diagonal dimension of THIS camera sensor

If the Crop Factor is 1.5x, that means that a 35 mm film frame diagonal is 1.5x larger than this sensors diagonal. The image shapes may not be exactly the same, so we compare diagonals as representative of the sizes (the circular lens image, so to speak). But we know with absolute certainty that the 35 film frame is 36×24 mm, so Pythagoras tells us its diagonal computes 43.2666 mm. So in this 1.5x Crop case, rearrangement with the easiest algebra tells us the 1.5x crop sensor's diagonal has to be 43.2666 / 1.5 = 28.844 mm dimension. Now that we know its diagonal and know that the Aspect ratio is 3:2, we can compute the frame size is 24x16 mm, which is the proper sensor size (for crop factor of exactly 1.50x). Or, there are calculators here that do it, see more at Determine Crop Factor.

Crop factor simply compares sensor diagonal to 35 mm film size, and we know all about 35 mm film size. Crop factor is a rounded number (all specifications are rounded numbers, aspect ratio, sensor size, focal length, crop factor, megapixels, etc.), but probably are close, likely within a couple of significant digits (just don't expect extreme precision). For example, Nikon 1.5x crop is a nominal number, and it might often be about 1.52. Canon 1.6x is a nominal number, and it might be about 1.63. But these at least offer two significant digits of precision, so FoV and DoF results should be within two significant digits. Focal Lengths are also nominal, and not likely any closer than that. And our guesses at distance are even more suspect. 😊

Aspect Ratio:   Generally DSLR cameras are Aspect Ratio 3:2, and phone and compact cameras are Aspect Ratio 4:3. More specifically, digital crop factors of LESS THAN 2x are 3:2. Crop factors of 2x or higher are 4:3, with the exception that crop factor 2.7x (called One Inch, or CX format) is instead 3:2. If any issue with knowing Aspect Ratio, a little calculator here will compute it from your image dimension in pixels (a full size image straight out of the camera, and NOT subsequently cropped to a different shape).

Video formats today are 16:9 (HDTV format), regardless of crop factor. Another issue of image size is about Aspect Ratio of Mixed formats (movie vs still photo formats in same camera), see more info below.

Computing Sensor Size from Equivalent Focal Length (35 mm film)

If you don't know crop factor, it can be computed from the Equivalent Focal Length specifications for your lens (if available. It is often in the user manual and online product sites and advertising, and often in the image Exif data). This is common for compact cameras, less likely for cell phones, except iPhones seem to show it in Exif data).

Crop Factor =

Equivalent focal length on 35 mm film
Focal length of lens on THIS camera

Then knowing crop factor, we can compute sensor size as just discussed above. One of the four calculators at Determine Crop Factor will compute this from Equivalent Focal Length (35 mm), and the other calculators here (DoF, FoV, etc) also offer to compute it too.

This method is very valuable for when there is no clue about actual sensor size (specifically phones and compacts, but DSLR usually tell us sensor size). Generally compact camera lenses zoom, and the lens specs offers Equivalent Focal Length.

Make no mistake, Equivalent Focal Length is NOT your cameras focal length. Your camera has its own lens and its own actual focal length. But Equivalent is a size comparison to the Field of View of 35 mm film cameras, and so it can be used to compute your cameras sensor size.

Again, it is very necessary to know that this "Equivalent" DOES NOT MEAN it is the focal length of Your camera. Instead, "Equivalent" is the computed focal length of a hypothetical lens that 35 mm film would use in order to see the same field of view as your camera sensor sees with its lens. The Field of View is equivalent, NOT the focal lengths. It is merely a way to compare the Field of View that the different cameras would see. If you have some years of 35 mm film experience, then this comparison probably immediately tells you what field of view to expect from your new digital camera too. Otherwise, Equivalent Focal Length is simply NOT MOUNTED ON YOUR CAMERA, and it really has little use to you and your camera, other than this current discussion above can use it to be very useful to determine your sensor size.

Image Exif data: Another possibility is that the cameras image Exif data should show the actual focal length, and some cases may also show the Equivalent Focal Length (for 35 mm film). This is not always easy, and it is not always even there, but it can make all the difference if you need it. If you cannot even find the actual focal length in the image Exif data, then you might just need a better Exif tool, many are years out of date. See my notes about the classic free tool "ExifTool", which does everything and can get complicated, but included there are my notes about installing it the useful way that makes it into a simple easy-to-use Windows viewer program. It's great, and free, and always up to date. The way that sometimes works best for me is to select the ALL tab in the viewer, and then menu Export (to text file), and Equivalent Focal Length may be in the last Composite section of that text file (I have good luck with Canon compacts and Apple iPhones).

Examples computing with Equivalent Focal Length:

Seven compact cameras listed next all happen to say they use a "1/2.3 inch" sensor, from which the Wikipedia chart says the 1/2.3" W×H sensor size is 6.17 x 4.55 mm, and crop factor 5.64. And some 1/2.3 inch chips probably are, maybe some of these are close too, but (for compact cameras) the lens specification (in camera product advertising like in the B&H listing, and in the user manuals, and on manufacturers web site) also show the lens specifications below. But the rounding of camera specifications (including focal length and aspect ratio) can also make slight computing differences, judged to be insignificant in the big picture.

The Equivalent Lens specs are defined by sensor size, and then this reverse computing method would use the (35 mm film Equivalent) / (matching actual focal length) to compute Crop Factor, and from that, the sensor size. You also need to use the correct 4:3 Aspect Ratio for these. The 1/xx inch sensor size is just a nominal value, each one has a few size variations. Comparing several compact cameras all of 1/2.3" sensor size, the specs are:

1. The Canon PowerShot SD-770 ELPH compact camera (1/2.3") specifications for lens is:

"Lens Focal Length: 6.2-18.6mm f/2.8-4.9 (35mm film equivalent: 35-105mm)"

and values 35/6.2 (or 105/18.6) compute Crop Factor 5.645. Both the Crop Factor or Equivalent Focal Length methods compute sensor size of 6.13 × 4.6 mm (for Aspect Ratio 4:3), which width is 0.6% smaller than the 6.17 x 4.55 mm the Wikipedia chart indicates, and the crop factor agrees closely with Wikipedia.

2. The Nikon Coolpix A10 camera (1/2.3") specification for lens is:

"Lens Focal Length: 4.6-23.0 mm (angle of view equivalent to that of 26-130 mm lens in 35mm [135] format)"

The 26/4.6 (or 130/23) computes Crop Factor 5.652, which computes sensor size of 6.12 x 4.59 mm (for Aspect Ratio 4:3), which width is 0.8% smaller than the Wikipedia chart indicates, but the crop factor agrees.

3. The Sony DSC-W800 camera (1/2.3") specification for lens is:

"Lens Focal Length: 4.6 to 23mm (35mm Equivalent Focal Length: 26 to 130mm)"

The 26/4.6 computes Crop Factor 5.652, which computes sensor size of 6.12 x 4.59 mm (for Aspect Ratio 4:3), which width is 0.8% smaller than the Wikipedia chart indicates. The Sony W800 and Nikon A10 sizes agree with each other.

I first tried to look at a Sony DSC-HX80, also called 1/2.3", which worked fine, but is a bit different than these others. Sony specs say it uses the Exmor CMOS chip, and the Wikipedia chart has that too, with crop factor 5.49.

4. The Canon PowerShot ELPH 360 compact camera (1/2.3") specifications for lens is:

"Focal Length: 4.5 (W) – 54.0 (T) mm (35mm film equivalent: 25–300 mm)"

and values 25/4.5 (or 300/54) compute Crop Factor 5.556 (the W is Wide angle zoom, the T is Telephoto). Both the Crop Factor or Equivalent Focal Length methods compute crop factor of 5.556 and sensor size of 6.23 × 4.67 mm (for Aspect Ratio 4:3), which width is 1% larger than the 6.17 x 4.55 mm that the Wikipedia chart for 1/2.3" indicates.

5. The Olympus TG-5 camera (1/2.3") specification for lens is:

"Lens Focal Length: 4.5 to 18mm (35mm Equivalent Focal Length: 25 to 100mm)"

The 25/4.5 (or 100/18) computes Crop Factor 5.556, which computes sensor size of 6.23 x 4.67 mm (for Aspect Ratio 4:3), which width is 1% larger than the Wikipedia chart indicates. The numbers for the Canon 360 and this Olympus agree with each other.

6. The Panasonic DC-FZ80 compact camera (1/2.3") specifications for lens is:

"3.6 to 215mm (35mm Equivalent Focal Length: 20 to 1200mm)"

and values 35/3.6 compute Crop Factor 5.556 (the long end rounding computes 5.581, 0.45% difference, and I'd use the short end numbers). Both the Crop Factor or Equivalent Focal Length methods compute crop factor of 5.556 and sensor size of 6.23 × 4.67 mm (for Aspect Ratio 4:3), which width is 1% larger than the 6.17 x 4.55 mm that the Wikipedia chart for 1/2.3" indicates.

7. The Nikon P900 camera (1/2.3") specification for the lens is:

Lens Focal Length: 4.3-357mm (angle of view equivalent to that of 24-2000mm lens in 35mm [135] format)

This Crop Factor is the 24/4.3 = 5.58 computing sensor size of 6.2 x 4.65 mm (for Aspect Ratio 4:3), which width is 0.5% larger than the Wikipedia chart (or 2000/357 = crop 5.60). The camera has only its one sensor so these two ends must compute the same Crop Factor, however, focal length rounding can cause a slight difference, especially very long numbers, and chances seem good that the long 2000 mm end is rounded heavier (but there is only 1/3 of 1% between these two crop factors, insignificant, but I'd use the short end numbers.)

Comparison
1/2.3" Sensors
Crop
factor
Width
mm
Height
mm
-- Wikipedia 1/2.3"5.646.174.55
1. Canon SD-7705.6456.134.60
2. Nikon A105.6526.124.59
3. Sony DSC-W8005.6526.124.59
4. Canon 3605.5566.234.67
5. Olympus TG-55.5566.234.67
6. Panasonic DC-FZ805.5566.234.67
7. Nikon P9005.586.204.65

Computing with this Equivalent Focal Length method is very commonly possible for compact cameras. It is a slight approximation, as shown in the chart here, that a few different sensor dimensions might all be called the same closest standard 1/xx number. And rounding (of focal lengths and crop factor and aspect ratio) also makes slight differences in the numbers you may compute. The 35 mm film diagonal is 43.2666153 mm (used here), but which can be rounded itself a few ways. If Aspect Ratio is 4:3 (also rounded), then the dimensions (rounded to two decimals here) calculated from the crop factors mentioned here compute as shown in the chart. And realize that a distant large field of view is just the sensor size enlarged greatly, which magnifies any little differences too.

So the point is, the 1/xx inch number involves approximations and rounding, but is still probably close enough for Depth of Field or Field of View purposes. Our own distance estimate is likely a larger issue for that precision. But instead of the 1/xx inch number, I'd prefer to use the Equivalent Focal Length method, which at least comes directly from the camera manufacturer.

Since the compact camera zooms, the focal length actually used for a random photo is probably a different number than these end points, but it will be shown in the image Exif data. It is however reported in the Exif, in steps that are not always quite the precise actual. All of the numbers are rounded, but it's what we have to work with. I don't see the harm if the manufacturers simply bothered to show the actual sensor size in the camera specifications, but it hasn't been important to them.

These seven compact results are in near agreement. These seven widths are within about ± 0.05 mm (within 1%) of the Wikipedia approximation, and these seem good examples of what you will find (and I suspect it is going to be ALL that you can find for sensor size of compacts or phones). These seven cameras use different sensor chips with varying megapixel size. All of these specification numbers are rounded values, and for example, 4.3 and 24 mm are only two significant digits. But the differences are small, and your estimate of field distance is not likely even that accurate anyway.

iPhone: The iPhone XR does not specify a 1/xx inch number, but its image Exif (using either of the mentioned Exif tools) reports these next two corresponding values (but which are Not adjacent to each other in the Exif there, you have to hunt a little for each of them):

Focal Length : 4.3 mm   (this is your camera's real number for actual focal length, found in the Exif)
Focal Length In 35mm Format : 26 mm   (Equivalent Focal Length, used on a 35 mm film camera)

Do NOT use Equivalent focal length as your cameras focal length, because it's Not. Not all phones Exif shows this Equivalent Focal Length, but iPhones do seem to show it.

This Exif data comes from the cameras manufacturer, and they show correct numbers. This focal length is 4.3 mm.

From this 26/4.3, the calculators compute Crop Factor 6.0465, and sensor dimensions of 5.72 × 4.29 mm (for Aspect Ratio 4:3). Finding sensor size can be pretty easy this way. The calculators will easily do this for you if you can supply your numbers to use. Since this lens does not zoom, then its focal length that you would specify used is the 4.3 mm it shows. If it did zoom, then the spec shows zoom end points, but the Exif also likely shows the zoom value in use.

Otherwise, if Equivalent Focal Length is not found, then the real focal length should be in the Exif, and maybe the 1/xx inch sensor size is shown in specifications.

Which method is most accurate? So far, I don't think we have any precise information that could tell. But the manufacturers do tell us the focal lengths, and other than rounding, I see no reason to doubt it. I'm very comfortable with this Equivalent approach because it's just simple math about the sensor size, and it is a manufacturer's spec actually for this camera, which can't be far wrong. It may be all we know, but at least this measurement info comes directly from the manufacturer. However, I don't understand why their camera specifications can't just simply tell us the actual sensor size. We already know they are tiny. 😊

If it were a phone camera, then this same info may be in the image Exif data (at least for iPhone, maybe not others). But these are the focal lengths in the spec, or maybe in the Exif data for a lens that does not zoom. It is NOT about intermediate zoomed values, which are approximated even more. Please see other detailed instructions. Be sure you understand the method shown here, because improper input simply computes wrong results.

While Equivalent focal length may not have any practical use for very many users (unless they also have much 35 mm film experience), the math makes it very useful for computing sensor size (it's just a simple comparison of sensor size with 35 mm film format). But DO NOT misunderstand: NEVER use any Equivalent Focal Length for computing, only specify your own camera's lens actual focal length used there. It is the lens you actually use. The Equivalent focal length is on another hypothetical 35 mm film camera, NOT on your camera. However Equivalent can be used this special way to compute your sensor size from its ratio to 35 mm film size (which is well known).

Discrete Steps in Zoom focal lengths

Math is accurate, but input data is less so. One variable (of a few) affecting computing results is that while zoom lenses focus continually, they report intermediate zoom numbers in several relatively coarse discrete steps (not continuously), which can lose precision then, with the reported value possibly not quite matching the actual number. Which is generally not important in use, and a lens operates adequately for its design purpose, but the steps can't be continuous.

An example: A superb Nikon 24-70mm f/2.8 lens was nearly \$2000 in 2007 (assumption: no manufacturing expense was spared). Its zoom ring marking is 24 - 28 - 35 - 50 - 70 mm. I made 14 exposures in tiniest steps between 24 and 28 mm. Unmeasured, but intended to be fairly equal tiny steps of rotation. Zoom is not linear, but the Exif reported results of 3 pictures at 24, 5 at 26, 4 at 27, and 2 at 28 mm. Also 19 similar unmeasured steps between 50 and 70 mm (each at a tiny zoom difference) reported 1 picture at 50, 1 at 52, 2 at 55, 3 at 56, 2 at 58, 3 at 60, 4 at 62, 2 at 66, and 1 at 70 mm. Those are the step sizes at these focal lengths, which is impressive, yet not fully precise.

The zooming is continuous, NOT in fixed steps, however the reporting of focal length is necessarily in fixed steps. There are little areas between steps where they cannot agree precisely. We cannot set a specific zoom focal length value exactly, and it is not reported exactly. This is absolutely not an issue for photography, as we judge the viewfinder view without concern about the actual number, however calculations require a precise accurate value.

So if you're going to compute with it, it has the effect of losing precision of the numbers, and you ought to know that this situation exists (in this example, steps of 66 and 70 mm are about 6% apart, reported as either step, but not in between. But this is more about precision than accuracy). The point is, using either end of the zoom range (even though these are still rounded values) are likely better known values (in the specs), and could be a bit more precise than intermediate steps. But published camera specs are typically nominal, perhaps approximate values, or at best rounded values (including focal length, sensor size, aspect ratio, crop factor, equivalent focal length. And distance reported in Exif by zoom lenses can be much worse.) The camera obviously achieves its camera purpose, but it simply is NOT a precision measuring instrument.

Mixed format (video and still shot formats) with same camera sensor

Such mixed formats can be an issue. We can make assumptions (but we are rarely certain). For a 3:2 or 4:3 sensor, we can assume the 16x9 HD video choice is fitted to the full available width, and the 16:9 height will be appropriately shorter in height. Or for an actual 16:9 camcorder sensor, any still photo of ratio 3:2, 4:3, or 16:9 options compute the sensor height that fits that original 16:9 frame. If the sensor is 16:9 size, then 3:2 or 4:3 photos cannot exceed that sensor height (which means they become more narrow, see diagrams below). This mixed format case with video may take some attention to determine what you actually have, and if these assumptions are actually true. See the 16:9 notes below. Some camcorders provide still photos that are also 16:9, which can be specified.

Aspect Ratio: Aspect ratio is the SHAPE of the sensor. Numerically it is the ratio of width to height. If Aspect Ratio is unknown, look at the size of your images (pixels) straight from the camera. For example, maybe the size is 4320x3240 pixels. Divide Width by Height. For example, 4320 / 3240 is 1.3333:1. Common camera Aspect Ratio values are:

1.3333 is 4:3 (also = 4/3) - Compacts and phones
1.5     is 3:2 (also = 3/2) - DSLR
1.7778 is 16:9 (also = 16/9) - Camcorders

HDTV 16:9 movies: Special considerations. The differences in the Aspect menu in Option 3 above is about the difference in camcorders from DSLR, compacts and phones. Someone might find some exception about some specific camcorder, but generally:

Still cameras (including DSLR, compacts, phones) today are usually more or less around 10 to 24 megapixels. They have 3:2 or 4:3 sensors, and take 3:2 or 4:3 photos of that size, and their diagonal fits the diameter of the lens circular view. Their HDTV movie sensor frame size is likely slightly smaller than sensor width to optimize the subsampling, but can't be larger. And HD movies will necessarily be output at 1280x720 or 1920x1080 pixels (about 1 and 2 megapixels) — which is the maximum that HDTV can use. The 16:9 movies in still cameras are constrained within that still camera sensor size, limited by the same width.

HD movies are typically only about the necessary HDTV 1 or 2 megapixels, camcorders often can output still photos with much greater megapixel counts. Camcorders have 16:9 sensors, which fits the full movie diagonal, not constrained by any 3:2 or 4:3 sensor width like still cameras. Generally, if camcorders also take still pictures, those may be 16:9 too. But if they do provide 4:3 still photos (Sony does), those are necessarily horizontally cropped to be constrained within the height of the 16:9 sensor, limited to the same height. These situations will require some attention to know what you have.

This is a complication about the field of view of movie recordings in still cameras, and in still pictures from camcorders. These are assumptions, but we're not always too sure about the sensor area used by mixed formats. The calculators use these assumptions, and can differentiate these differences (aspect ratio choices can match the yellow drawings).

In this image at right, the blue circle represents the image that the lens projects. Sensor diagonals are designed to fit that circle. 16:9 in camcorders is wider, if not constrained within the more narrow sensor frame sizes. I suppose there could be some exception, but camcorders should have a 16:9 sensor, and DSLR, compacts and phones typically have 4:3 or 2:3 camera sensors. Their 16:9 width will be the same as the 4:3 width, but then the height is less.

Determine aspect ratio by dividing image width by the height (both in pixels), which is its aspect ratio. 3:2 divides as 1.5, 4:3 divides as 1.3333, and 16:9 divides as 1.7778. So if your camera takes still pictures of aspect 1.7778, then it is probably a camcorder with a 16:9 chip.

We can make assumptions imagining how it ought to be, but the size of a 16:9 image in a 4:3 sensor (or vice versa) possibly has unknowns about the actual effective sensor size.

However, by making the following mixed format assumptions (like the yellow diagrams), the calculator offers Aspect Ratio choices that do the extra work to compute that cropping and the sensor area used (uses what will fit on the chip).

If 16:9 video from a 3:2 or 4:3 camera, then assume video is full width of the chip, but is shorter height as required.
If 3:2 or 4:3 from a 16:9 camcorder, then assume still photos are full height of the chip, but are less width as required.

If images are native chip format (not mixed format), then it uses full chip size. So actual real camcorders outputting 16:9 images should be no concern, but some mixed formats may or may not be full chip size (example next below). But if the assumptions are accurate, the calculation should be accurate.

Some photo cameras will use their full sensor width for their HD movie width (Nikon D7100, D600, D750, D850 manuals do specify their movies are full sensor width) and that method is assumed here, and is possibly even common, and possibly correct.

But for example, the Nikon D800/D810 use slightly less width for video, but does specify those dimensions (diagram is D800 page 67). Those manuals specify the sensor image area for FX HD movies is 32.8 × 18.4 mm FX, and says DX HD is full width of 23.4 × 13.2 mm. That is 32.8/35.9 = 91.36% of full width for FX and 100% for DX. If you know those mm dimensions, you'd use them instead.

And an iPhone 5S also appears to limit the movie width field of view to be about 90% of its JPG too. I don't know why, my wild guess is to minimize vignetting (which is worse with wide lenses at wide apertures) when mixing shots with those of other lenses or other cameras? I doubt many camera manuals mention their method. If we always knew the mixed format movie sensor dimensions were full sensor width, then we could easily compute the sensor area and the movie field of view too.

Camcorders probably will be difficult. Just for an example to mention things you may see, a Canon R-300 camcorder has specifications in the user manual (page 217) as follows:

The crop factor is the 38.5 mm Equivalent focal length / 2.8 mm focal length, which is Crop Factor 13.75x. Page 51 says Optical zoom is 32x (which is the 89.5/2.8 range specified), and says Advanced Zoom is 51x and "beyond the range of optical zoom". Which is not optical zoom by the lens. And there is another called Digital Zoom that does 1020x. The optical lens specification is what is important.

First way: So the crop factor is 13.75x (presumed the native 16:9 because it says a little further down: Size of Photos: 1920x1080 pixels), from which the DoF or FoV calculators compute the sensor size as 2.743×1.543 mm, diagonal 3.147 mm. That should give good estimates of Depth of Field or Field of View.

Another way: It also says it uses a 1/4.85 inch sensor, but this time, the Wikipedia chart does not go that small. Checking with the very rough estimate of 60% of 1/4.85 inch is 0.60 x 25.4 / 4.85 = 3.14 mm diagonal, ballpark, which is very close here (computes 13.78 crop factor). And a little further down, it says Size of Photos: 1920x1080 pixels, so the still photos are the same 16:9 format, and it reads like a native 16:9 sensor.

It does not mention if video is full width of the sensor or not, but you could compare the same fixed scene on a video frame and a still photo frame. The First way does not need to know, it uses the 16:9 specs directly. The second way might need it, but it matches too close to suspect needing it.

For a Sony AX33 camcorder: (user manual)

First way: Page 46 says 1/2.3 inch (7.76 mm) Exmor R sensor, for which the Wikipedia chart says 6.30x4.72 mm and 7.87 mm diagonal and crop factor 5.49x, but these are 4:3 dimensions, not 16:9 (6.3/4.72 = 1.335). Sony is saying their diagonal is 7.76 mm, but that is about the 4:3 chip.

The DoF calculator with Wikipedia crop 5.49 and the calculators "16:9 in 4:3 camera" aspect option computes 6.305×3.546 mm, diagonal 7.234 mm. But Sony indicates their video is about 90% of this (second way next), which is then maybe about 5.67x3.19, diagonal 6.51 diagonal (all these numbers are rounded). But there's more.

Another approach: The lens is clearly stated as 3.8-38 mm zoom. Then it says "When converted to a 35 mm still camera" (which means Equivalent focal length on 35 mm film), it says "For movies: 29.8-298 mm" and "For photos: 26.8-268 mm" (16:9 still photos). Both clearly say 16:9, which then the longer movie zoom numbers can only mean that the frame of the movie is about 90% of that frame used for still photos (26.8 / 29.8 = 89.9%, but all these numbers are rounded). Notice that all of these numbers come directly from Sony for this specific camera. And if these are 16:9 numbers, describing the 16:9 frame size, so to use these numbers, now we reference the 16:9 frame area as if it were native.

These Equivalent Focal Length numbers compute:

ModeEquiv FLActual FLCrop FactorWidthHeightDiagonal
Movies 16:929.8 mm3.8 mm29.8 / 3.8 = 7.8424.8092.7055.515
Photos 16:926.8 mm3.8 mm26.8 / 3.8 = 7.05265.3473.0086.135

Under "Image Device" it says Max 20.6 megapixels 6048x3400 pixels, which it says is 16:9. That 20.6 is rounded, and 6048x3400 = 20.5632 megapixels (which can round to 20.6). If this precise 20.5632 is entered into the Megapixel calculator with 1.7778, it gets the 6048x3400. Then it says the movies are 8.29 megapixels (page 12 says is 4K movies, for which I compute 3840x2160, which is 2x 1920x1080). And photos (16:9) are 10.3 megapixels (I compute 4280x2408) and photos (4:3) are 7.74 megapixels (I compute 3216x2408). Still some questions about sensor mm dimensions, but at 16:9, again, these movie frames are 90% of still frame dimensions, which we could also apply to the 1/2.3 inch sensor dimensions for video sensor size.

At least they are telling some things, but I'm still confused. A summary of the numbers:

ModeMegapixelsPixelsAspectLens
crop factor
Max 16:920.66048x34001.7778
Movies 4K8.293840x21601,77787.842
Photos 16:910.34280x24081.7778
Photos 4:37.743216x24081.33337.0526

Actually knowing the precise sensor size is the key to Field of View or Depth of Field accuracy.

And there is also a FoV Math section for FoV.