Put the end of the measure at one end of the item or space you want to measure. If you don't know your compact or phone sensors accurate W×H mm dimensions, but you can find the Equivalent focal length (compacts and iPhone typically supply this, in specs or maybe in the image Exif, see the help link here), then consider either of Sensor Size Option 2 or 3 below to compute your sensor size (and specify the correct Aspect Ratio). The 1% differences mentioned here seem insignificant, and are likely more accurate than your description of the Object in the photo. What we are told about any camera can be a bit crude. One method then to approximate the actual sensor Width x Height in mm from that 1/inch number is to try this Wikipedia chart. But for still images, the image Exif data normally shows lens focal length, for compacts and cell phones too (and is likely about all you will ever know about the cell phone lens). Since this lens does not zoom, then it’s the one actual real focal length used. But Compact and especially cell phone cameras often don't bother to tell us much. You specify if you are measuring width or height direction, and also how the camera is rotated to determine which dimension is that width or height. Spring return pocket tape measures will generally fit in a pocket. 6) Path - allows to calculate the length of the path. The most accurate way, after i measure the size of virtual ruler by a actual ruler, i found the markings are not very accurate at 30cm, so i adjust the default pixels per inch(PPI) to 100.7, now i get an online actual size ruler. Tall vertical objects will still be foreshortened with angle, but will not tilt back then if the camera is level (if the camera back is perpendicular to the horizontal). Any meaningful accuracy needs you to to be pretty confident that you do in fact actually know your cameras actual sensor size and focal length. Online Ruler (cm/mm) Label. Free online ruler. Instead, we need to know the actual exact size of the digital sensor, which must be Width×Height numbers, in mm. Sensor size is fixed (same one sensor for any zoom). There are plenty of issues when trying to determine the sensor size of compact or phone cameras. For a versatile tool fit for household projects, crafting and decorating, consider a shorter tape measure that is 12 feet or 16 feet in length. This is a common error, so please DO NOT USE EQUIVALENT FOCAL LENGTH as your camera's focal length, as that would be meaningless. The printable rulers here are a little more fashionable with either a metallic … Then knowing 56% of the camera sensor height in mm, and also the real life height, and the focal length distance in camera, it calculates distance to the subject. Measure a length. If it's a still photo image (not a movie image), the focal length should be shown in the Exif data, which you can see there. This is a convenient online ruler that could be calibrated to actual size, measurements in cm, mm and inch, the upper half is the millimeter ruler and centimeter ruler, the lower half is an inch ruler. If both the sensor plane and the object are vertical, then these are parallel at any object position, so there is no tilting (no walls falling backwards), but larger angles can still cause foreshortening of vertical dimensions. All you need is a pair of scissors to cut it out. We normally think of “Sensor Width” as the larger number of mm and pixels, but if camera is rotated up on end, the larger number will become vertical “Image Height”. Do not kid yourself when the calculator shows precision of a couple of decimal places. Users with years of experience with 35 mm film find it useful to know in those familiar terms what the field of view of this digital sensor will now show. If any doubts, you can repeat a similar test. 3:2 in 16:9 camcorder It won't work correctly for macro distances or for fish eye lenses. paper should measure 29,7 centimeters or 11,6 inch vertically. This example may verify the math, but cameras have many variables, often not known well enough. Don't forget to account for your camera height above ground level. Move your device slightly, and the object's calculated area appears. However, the Exif data says this Focus distance was 3.76 meters, which is 12.33 feet (but was 30 feet when it was actually measured), so don't trust that number (especially not in zoom lenses. When the length stops, take a reading on the tape measure. Cut out the ring sizer and open the slot where marked. Because this is NOT an easy question about small cameras, requiring a bit of technical understanding. First, two very common mistakes to avoid: Equivalent focal length is instead used by another 35 mm film camera to then show the same field of view as your camera sees. Remember that you can simply Level the camera until you see them straighten. So if using a compact or smart phone camera, or a camcorder, you may not know the necessary numbers for this calculator. Or work with a copy of the file.). Do not expect camera results to normally be this accurate. This will result in an fit to scale & accurate ruler. The math is easy, but maybe it was a lucky result, and maybe NOT a typical camera result. If you understand how, you can enter exponential nomenclature (for example 1.5E4 is 15000). It assumes the camera is level, aimed horizontally. You do need to have reasonable confidence and knowledge that your inputs are accurate data. Equivalent is the field of view referenced to the different camera. Rotated, Largest mm seen as Height, Aspect Ratio  If you do need precision measuring, you should get a different instrument intended for the purpose. Very adequate for its design purpose, but it can't be continuous. We know the bottom number will be /8 because of the size of the line (see photo above). Use the actual number for Your lens. Accuracy: Math is accurate, but input data is less so. If perhaps a compact, your picture may have used one of those end point focal lengths, or used another intermediate one, like 10 mm focal length, and that's the number that the scene description wants (to compute the picture). These lasers double the range of a standard 25-foot tape. I am at fault by speaking of this one result as if it is fully meaningful. 7) Height - allows to tape measure height relative to the recognized surface. Zoom lenses normally specify their minimum and maximum zoom focal length, but we don't know any other value. 7360x4912 pixels. However, from the lens spec, the 35 mm Equivalent focal length / Your Camera's actual focal length is the Crop Factor of your sensor size. What Size Tape Measure Should I Use? For construction or measuring large areas, up to 35 feet is ideal. Substituting an Object size instead of Field size. Width and Height: For sensor dimensions (mm and pixels), the calculator asks if you are measuring in Width or Height in the photo (where Height always runs vertically in the photo image). The calculator works measured in either height or width of the sensor, but not if on an angle. Bottom line, do not trust the Exif focus distance number unless you have tested it at the similar zoom and distance. And since we know all about the size of 35 mm film, we can then use this Equivalent focal length to get Crop Factor to determine the size of the sensor on your camera, for use with this calculator. That is not wrong exactly (if you realize the 26 mm is mounted on a different camera, not this one), but it is poorly worded, not useful, and it steers beginners wrong. It can compute your accurate sensor size, and it may be the only manufacturers specification you can ever find for compacts and phones. Before bothering to start calculation here, users (especially Compact and phone camera users) should Please read the Help material below, plus the section following immediately next, for help determining the camera's sensor size and focal length values. The calculator uses those rounded values to compute ratio numbers, and then any input errors are magnified in the external field dimension results. The reason results may not be precisely accurate is that camera specifications round the values of Focal length, Sensor size in mm, and Crop Factor. Most devices from various manufacturers are supported (see below for full list of devices). 6) Height - allows to tape measure height relative to the recognized surface. These compact cameras do reset to one default focal length when turned on, but which we really don't know that value either. Otherwise, it suggests the image has been cropped to a different size than the sensor. A little robot one and another one where the measure is the tongue of a frog and so forth. This same math is repeated and expanded a bit at, users (especially Compact and phone camera users) should Please read the Help material below. Assuming familiarity with using 35 mm film, the intended significance conveyed by 26 mm is that it is a wide angle lens (on 35 mm film), more than moderately wide, but substantially less than ultra-wide. Still, the accuracy seems very adequate (at distance ranges of at least several feet). Except new phones with separate Wide and Telephoto cameras use two sensors, which possibly are Not the same size or focal length. The sensor size Option 3 is intended to make sensor size be easy for phones and compacts. It absolutely does NOT mean THIS phone lens is 26 mm (the phone lenses vary some, but are very roughly around 4+ mm). However, Crop Factor does compare the sensor sizes directly. Please make sure you are printing at 100% or actual size to the rulers will stay true to size. Not knowing the accurate input data can be a HUGE problem for calculations. Find the length. Hold a blank paper against your ruler as shown on the image. It is designed to fold back on itself to join the ends and create a longer measuring tape. The calculator above will do this, but it needs your accurate numbers. You can use the Printable Ruler 32nds Inch for many distinct makes use of. Pocket tape measures have a tape 1 to 15 feet (0.30 to 4.57 m) in length and 1 ⁄ 4 to 3 ⁄ 4 inch (6.4 to 19.1 mm) across. Handy & Accurate Online Ruler. Photo Ruler app is designed to accurately tape measure the size of any object by either taking a picture of it or to measure it on the screen. The 150 mm one also has the 6” markings on the opposite side. Larger cameras normally actually specify the W×H mm sensor size directly, which is a plus (but video formats can still be an issue). These are just comparisons to 35 mm film size. A NaN result will mean an input is Not A Number. It's the same percentage of the distant field. This same material has a little more explanation at Field of View Math, so please see that also (not all is repeated here). The options will compute and change the appropriate field, where the Pink background will appear. Equivalent focal length is the focal length used on another camera, specifically a hypothetical 35 mm film camera (which is of known size and is the standard reference of comparison), which will produce equivalent Field of View size on THAT 35 mm film camera. Nikon 60 mm f/2.8 D lens. You should not imagine magical precision from the camera numbers. Copyright © 2015-2020 by Wayne Fulton - All rights are reserved. Restrictions: You need the original digital image. That’s the only purpose here. Less precision in a smaller image or object due to less possible cropping accuracy, even one pixel is a bigger deal then. The Object Size should be in the horizontal or vertical plane, meaning Not tilted, angled, or skewed, which is a serious complication. For example, you have 100 hundred dollar bill. That 0.07 foot is 0.8 inches, which might be my error, because that distance is computed to the standard Thin Lens node somewhere inside the lens, not really known exactly where it is (but the calculated value is to it, and Not to the focal plane mark at rear of camera). Cameras with interchangeable lenses generally specify all the lens and sensor numbers (or Crop Factor), accurately, even if rounded a bit. Do not expect camera results to normally be this accurate. Some web sites repeating phone specifications show an Equivalent focal length number instead of the real actual focal length the phone actually uses. Example for the iPhone: The iPhone XR does not specify a 1/xx inch sensor number, but its image Exif 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 this camera's real number for focal length, found in the Exif), Focal Length In 35mm Format : 26 mm (Equivalent Focal Length). Using these two steps may be convenient for pixels. But Equivalent Focal Length is not about your own camera, because it obviously must use its own lens instead. This is the most reliable and easy way. Also with mixed formats (both video and still photo images from the same camera). You googling "100 dollar note size", finding that it is 2.61 inches wide and then measuring … It won't work from a cropped image or a paper print. Which is NOT this cameras focal length, but this calculator can compute the sensor size from it. Any camera tilt up or down foreshortens height, and is a complication involving lots more math. Garbage in, garbage out. In the case of an imperial tape measure, there are generally 16 marks to the inch, meaning you can measure up to 1/16 of an inch. 16:9 camcorder It can be approximate and incomplete, and different sensors of same description might not be the same exact mm numbers. Measure virtually anything with your phone – accurately! I wrote the calculator thinking of DSLR camera numbers, and it is just simple geometry, and it works well (if we actually know the accurate input numbers). For the various calculators here, these. What Equivalence means is that this camera sees a field of view equivalent to what a 35 mm film camera would see if the 35 mm camera used the 26 mm lens. If any doubts, you can repeat a similar test. Field located in the example below, we can solve for the object in field... The accuracy seems very adequate for its design purpose, but it n't! 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Can ever find for compacts or phones show the Equivalent focal length of another camera,! Same description might not be a HUGE problem for calculations on, but are. Necessary numbers for this, you can see, the process for finding your size... It 's the same percentage of the real focal length ( not easy in simpler cameras.. Image measures 30 feet, which must be Width×Height numbers, and are likely more than.