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# Focal length calculator

### Focal Length Calculator Edmund Optic

Select index from list of EO's own optical substrates to help calculate focal lengths and principal points of any standard lens. Note: This calculator follows the standard sign convention for the optical radius of curvature where if the vertex of a surface lies to the left of the center of curvature the radius of curvature is positive,. Lens focal length calculator. Introduction. When taking pictures or filming a movie with a camera, a lens (or a system of lenses) is used to project an image of the scene we want to record on a light sensitive film or on a digital sensor (called imager). Imagers have different sizes but are usually fairly small (from a few millimeters to a few. Find the right lens quickly & easily with the Kowa lens calculator. Calculate focal length, field of view or working distance. Calculate here The focal length f´ virtually serves to calculate the required lens and is thus the most important specification to characterise an (entocentric) normal lens. The theoretic value of the focal length calculation serves to find the best suitable optics. Typical increments of focal lengths for C-mount lenses are e.g. (1.8, 2.8, 4, 6,) 8, 12, 16.

### Lens focal length calculator - giangrand

1. The lenscalculator calculates the Focal length of the lens, based on the desired Field of View (FOV), working distance (WD) and image sensor size 30-50% cheaper than competitors Strong machine vision camera portfolio Excellent support Certified by TÜV Rheinland 3 Year camera warrant
2. Focal Length Lens Calculator. The focal length calculation is made with a simple formula, based on a single lens system and so the result is an approximation. Conventional lenses are composed of multiple lenses in lens groups, therefore, results may differ in practice. Under certain circumstances, the use of extension rings may be necessary to.
3. Calculate front focal length (FFL) by using simple optical calculator online. The distance from the front focal point of the combined lenses to the first lens is called the front focal length (FFL). If d tends to zero, the focal lengths tend to the value of f given for thin lenses in contact. If the separation distance is equal to the sum of.
4. ation and testing. It enables easy calculation of an appropriate lens focal length, camera viewing angle, IP camera bandwith, storage capacity for records archiving and of other camera system parameters
5. Crop Factor Calculator. Get the full-frame (35mm) equivalent focal length and aperture for different sensor sizes. Just enter the focal length and maximum aperture of your lens and then choose a sensor size. sensor, is equivalent to a 157.5mm f/2.1 lens. The crop factor for that sensor is 1.5x
6. Back Focal Length Calculator. Calculate back focal length (BFL) by using simple optical calculator online. The distance from the second lens to the rear focal point of the combined system is the back focal length (BFL). If d tends to zero, the focal lengths tend to the value of f given for thin lenses in contact. If the separation distance is.
7. Focal Length & Ratio Useful calculators and formulae. Focal Length Calculator. Calculate the focal length of your telescope. Formula: Aperture X Focal Ratio . Aperture: mm. X Focal Ratio: f/ = Focal Length: mm. Focal Ratio Calculator. Calculate the focal ratio of your telescope..

Effective Focal Length Calculation. The standard focal length is what the manufacturer writes on the lens. But the crop factor affects it. So, the effective focal length is the actual resulting value that the lens has on the camera with the crop factor adjustments. For your reference, sometimes it is called Effective Focal Range This online calculator allows you to calculate the 35mm equivalent Focal Length for a specific sensor size. You can find information on the sensor size in your camera in the manual, product information of the manufacturer of on DPReview.com. More information on the how an why of the Lens Multiplication Factor (also referred to as 'Crop Factor. Lens Focal Length and Stereo Baseline Calculator. This calculator helps you selecting the right lenses for your cameras. It does so by computing the desired focal length, the corresponding field of view and the expected depth of field. In case of a stereo camera, such as our Karmin3 3D stereo camera, the calculator also helps you selecting the. To calculate, enter the focal length and select the camera sensor. By default, the calculator will show a 35 mm equivalent focal length of the focal length you entered into the form. This is the focal length of the lens with an entered focal length that would give the same magnification on a 35-millimeter camera. Definitions and Formulas Calculate the Focal Length. The formula to calculate the focal effective focal length is f = d / (2 * tan (α/2)) , where. f= focal length. d= the vertical size of the sensor, in millimeters. (α/2) = the angle we calculated above. Note that the angle above ( A) replaces this entire expression, not just the α

### Lens Calculator Focal Length Working Distance Field

1. To calculate, enter the focal length and select the camera sensor. By default, the calculator will show a 35 mm equivalent focal length of the focal length you entered into the form. This is the focal length of the lens with an entered focal length that would give the same magnification on a 35-millimeter camera
2. Calculate Field of View, Focal Length or Object Distance by providing the other two properties. Step 1 Choose an Optical Format: 1.1 1 1/1.2 2/3 1/1.8 1/2 1/2.3 1/2.5 1/2.8 1/3 1/4. Step 2 Provide any two of the following three properties (A, B, or C): Unit of length: in. cm. The other two textboxes will fill when you click Calculate
3. Equivalent Focal Length for 35 mm film = Focal Length of lens on THIS camera x Crop Factor. 3. Calculate Equivalent Focal Length. Focal Length mm on. a Crop Factor x sensor ( ↑ the TOP) Equivalent focal length is conventionally compared to be used on 35 mm film size, which is called 1x full frame. Add x, x and x crops
4. 1: Atmospheric seeing conditions (the sky) often limits the maximum usable magnification to 250-350x. 2: An exit pupil size (diameter of light beam as it exits eyepiece) over 7.5mm might be too large for telescope designs with central obstructions (i.e. Newtonian telescopes). 3: Exit pupils less than 0.4mm are impractical because eye floaters.
5. The focal length of a camera is the distance from the center of the lens to the focal points. If the focal points are closer to the lens center, it means the lens has more optical power to converge the light. The stronger the power, the wider field, and there is a mapping relationship between the Field of View and the focal length

### Calculation focal length - Vision-Docto

Free photo app to calculate hyperfocal based on sensor type, aperture, and focal length. • Set your sensor. • Set the desired aperture. • Set the desired focal length. And see the corresponding hyperfocal distance in meters or feet ! ������. Read more This calculator will find either the equation of the ellipse (standard form) from the given parameters or the center, vertices, co-vertices, foci, area, circumference (perimeter), focal parameter, eccentricity, linear eccentricity, latus rectum, length of the latus rectum, directrices, (semi)major axis length, (semi)minor axis length, x-intercepts, y-intercepts, domain, and range of the. A depth of field calculator is a useful photographic tool for assessing what camera settings are required to achieve a desired level of sharpness. For a background on what everything here means, also see the tutorial on depth of field. Note: CF = crop factor (commonly referred to as the focal length multiplier The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power.A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light. A system with a shorter focal length bends the rays more sharply, bringing them to a focus in a shorter.

To calculate Focal Length Of A Concave Mirror With Real Image, you need Image Distance (v) and Object Distance (u). With our tool, you need to enter the respective value for Image Distance and Object Distance and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well Lens calculator for AXIS A8004-VE. Click the calculator icon next to the value you wish to calculate. Then drag sliders or enter values into fields to update results. Calculated results are shown on a yellow background. The camera uses a fixed focal length lens. Drag the distance slider to calculate scene dimensions, or enter values into scene. Compare the DOF of two lenses. Depth of Focus calculator. Hyperfocal Distance Calculator. Blue shift calculators. Optimal Aperture calculator. Diffraction Limit. Extension Rings from Object Distance and Focal Length. Extension Rings from Object Distance and Focal Length (interactive!) Extension Rings from Sensor Size, Object Size and Focal Length This calculator uses the actual focal length of the lens, not the equivalent angle of view focal length that photographers talk about when comparing things. So there's no need to do anything to focal length, just use the number that you had the lens set to. Also, to clarify a point

Focal Length Calculator. This tool is used to determine the focal point of a camera to help determine the best size lense to order. It uses the min and max value of a varifocal lens. Click the question marks for tips and help. F MAX Maximum focal length of a varifocal camera. EX: A 2.7-1.3.mm camera max is 13.5 The calculators below will help you determine the lens focal length you need. It is assumed the camera's sensor has a 4:3 aspect ratio, the sensor is a common size, and that you will use all the pixels. Or, try our new Machine Vision Lens Calculator instead. It is more flexible, and is smart enough to suggest specific lenses for your next project

### Lenscalculator Focal Lenght FOV Sensor siz

• mmCalc is a super simple photography focal length calculator. Simply input your focal length, sensor size, and max aperture and we'll give you what the 35mm equivalent is of that configuration. If the simple calculator doesn't suit your needs, we also offer calculators for crop factor based on sensor size and completely custom lens + sensor crop factor calculations
• Physics - Optics Calculate Lens focal length. Physics. Physics is the field of natural science, the science of the simplest and at the same time the most general laws of nature, about matter, its structure, and movement. The laws of physics are the foundation of all-natural science. Our calculator will help you solve physics problems
• imal focal length
• Focal Length Calculation of a Satellite Antenna. This calculation works for prime focus antennas is useful for checking that the dish is constructed correctly for maximum efficiency and the RF feed horn is in exactly the correct position. The Focal Length (FL) is the distance from the feed horn to the centre of the antenna
• ed by the index of.

### Focal Length Lens Calculator - Ricoh International B

• g step in the orthophoto generation process. I thought given this information beforehand would save considerable effort of the software
• ed by the focal length of a lens, the sensor format and.
• es how wide or narrow your angle of view is. Shorter focal lengths provide a wider angle of view, while longer focal lengths give a narrower view angle, allowing you to zoom in on distant objects
• Star Trail Lengths. You can use the calculator to estimate how long (or short) the star trails will be in a fixed camera image of the sky: where: F = Focal length of lens scope (trail length in same units as focal length) E = Exposure length. T = Length of sidereal day in same units as exposure
• Focal Length Result: 00.00mm. C. recommend using lens with closest FL to calculation
• Calculating the working distance using focal length, object and sensor size. a= f´* ( y / y´ +1) Note: Even when using the drop-down lists own values can be entered. Please use the first entry user def.

This calculator determines the focal length required to image a target at a specified field of view and working distance. To run, select the size of the sensor, either the horizontal or vertical field of view , the working distance to the target and then click the calculate button This calculator allows you to calculate the 35mm equivalent Focal Length for digital camera for a specific sensor size. Focal Length and Angle of view. The focal length of the lens is the distance between the lens and the image sensor when the subject is in focus, usually stated in millimeters (e.g., 28 mm, 50 mm, or 100 mm) Panorama Planner & Lens FOV calculator. Camera. Sensor Width: mm Sensor Height: mm Orientation: Portrait Landscape Lens. Lens Type Normal Focal Length: mm Focal Length: mm Panorama. Coverage 360° x 180° Full (360° x 180°) Partial Width: ° Top: ° Height: ° Overlap: %. This calculator computes the Field of View seen by your camera and lens. Field of View is an angle which depends on the focal length and sensor size, but it also computes dimensional Field of View sizes (width, height, or diagonal fields) at some specific distance, like at the subject distance, or at a background distance

Mirror Equation Formula. The following equation is used to calculate the radius of curvature and focal length. 1/O + 1/I = 2/R = 1/f. Where R is the radius of curvature. f is the focal length. O is the object distance. I is the image distance The focal length is a measure of the distance from the center of the lens to the foci of the lens. For this example, the focal length is found to be 500mm. Next, determine the diameter of the eye piece. This eyepiece is measured and found to have a diameter of 10mm. It's important that the focal length and diameter are in the same units.

Focal length. Angle of view. How to use lens simulator. You can simulate images shot with various combinations of lenses, ranging from wide-angle to telephoto, and cameras, in different formats. Image varies with the value of the focal length. Select any combination you are interested in Due to the focal length and the size of the imager (CCD or CMOS sensor), the visible range can be calculated. Image sensors consist of a matrix of light-sensitive components. The incident light transmits through the inner photoelectric effect its energy to the electrons of the sensor. The size of image sensors is usually given.

### Front Focal Length Calculator Calculation of Front Focal

1. To use this calculator, enter the following information: Focal Length of lens in milimeters. For an 18mm lens, write 18 regardless of the crop factor of your camera. The app will take care of the crop factor in the calculations. Aperture. For f/8, write 8. Select a unit of measure, either Feet, Inches, Meters or Centimeters. Select a Circle of.
2. imum declination of the stars that are captured in your frame. The first exposure time you get is less accurate (500 rule) but useful when you don't know the
3. Calculate Focal Length: Example 4 (Using Flexible working distance): My FOV is 508mm x 381mm, my sensor size is 8.47mm (diagonal). The ratio of working distance to focal length is 381mm/8.47mm = 45:1. So, if I choose a focal length of 25mm (which is about 1) then a working distance of about 1140mm (45) is required. If the maximum working.
4. The calculators you posted are for fairly standard, rectilinear lenses. This means you can use the Pinhole camera model to calculate the information. This graphic fairly well shows what is going on: On the horizontal axis you see f. This is the focal length of the lens. Then, the arrow labeled Y1 is the image plane (where the sensor sits)
5. Telescope Calculator Results: Focal Length: The distance (usually expressed in millimeters) from a mirror or lens to the image that it forms. In most telescopes the focal length is roughly equal to the length of the tube. Some telescopes use extra lenses and/or mirrors to create a long effective focal length in a short tube
6. Formula. Online physics calculator that calculates the concave mirror equation from the given values of object distance (do), the image distance (di), and the focal length (f). Code to add this calci to your website. Just copy and paste the below code to your webpage where you want to display this calculator

### Lens focal length calculator CCTV Calculato

1. Lens Focal Length Calculators. By Videology Inc. We'll be glad to help you. Americas, Middle East, Far East & Australia: 401.949.533
2. The basic formula to calculate the lens focal length is as follows: FL = (Sensor size * WD) / FOV. Using the values from our application, FL = ( 10.67mm * 400mm ) / 90mm. FL = 47.4mm. Lenses are only available off the shelf in various focal lengths (i.e 25mm, 35mm, 50mm), so this calculate is theoretical and may need an iteration to adjust.
3. Focal Length Calculator Parabola. It is proved in a preceding section that if a parabola has its vertex at the origin and if it opens in the positive y direction then its equation is y x 2 4f where f is its focal length. This calculator will find either the equation of the parabola from the given parameters or the axis of symmetry eccentricity.
4. In the calculator, just introduce your camera type (sensor size), aperture, focus distance, focal length ( the real one! not the equivalent in 35mm) and teleconverter to calculate the depth of field: Hyperfocal distance: The closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp
5. g with Your Bare Hands by steven schwartz February 20, 2014 Leave a Comment OK, it took me a little while to figure out why I'd want to use my hands to know which lens I'd need to compose a still picture or shoot a video

### Crop Factor Calculator Purple1

Calculator assumes a thin lens and uses the paraxial approximation. The calculator works for three possible scenarios: f > 0 and the propagation distance > f, f > 0 and the propagation distance < f, and f < 0. The larger the difference between propagation distance and focal length the greater the spot size will be DOFMaster LE Depth of Field Calculator(for Palm OS® platform) DOFMaster LE makes it easy. Tap three times to set f-stop, focal length, and focus distance. Read the near focus distance, far focus distance, and the hyperfocal distance The front focal length is then the distance between the front focal point (in the front focal plane) and the front principal plane (see Figure 2). Some authors define the focal length to be negative in the situation of Figure 2, because the focal point is located before the front principal plane; others take the absolute value

Fixed Focal Length Lenses. A fixed focal length lens, also known as a conventional or entocentric lens, is a lens with a fixed angular field of view (AFOV). By focusing the lens for different working distances (WDs), differently sized field of view (FOV) can be obtained, though the viewing angle is constant To obtain a clear, sharp image the screen should be adjusted. Using a metre scale the distance between the concave mirror and screen can be determined. The distance is the same as the focal length of the given concave mirror. Repeat the above procedure thrice to calculate the average focal length Before mounting the LNBF, you will need to know the dish Focal Length and the FD ratio. These two specifications are provided by the dish manufacturer. If these specifications are not available, they may be calculated with two measurements of the width and depth of the reflector. Focal Length = f Depth = c Diameter = D f = ( D * D ) / ( 16 * c If you have a 0.71x focal length reducer, you simply multiply the focal length of the lens by 0.71. E.g. 50 mm lens on 0.71x reducer = 35.5 mm lens. The crop factor doesn't affect the focal length. Also, the focal length is not the physical distance from the front of the lens to the sensor ### Back Focal Length Calculator Calculation of Back Focal ### Focal Length & Ratio Useful calculators - astronomy

Get creative with your lenses. The best 'zoom' lens is your feet! Why? Because changing focal length on your lens changes how your photo will look. It's best.. Lens Focal Length CALCULATOR. Param1. Enter the distance to the object you wish to image. mm. Param2. Enter the size (largest of either width or height-See discussion) of the object you wish to image. mm. Param3 The calculator uses the camera lens focal length equation. This formula is different than the lens maker's equation which is intended for simple thin lens elements. The Optical Effective Focal Length (EFL) should not be confused with the Mechanical Back-Focal Length (BFL)

### Effective Focal Length Calculator - Landscape Photography

1. Focal length formula to calculate focal length. When a lens is used to form an image of an object, the distance from the object to the lens (u), the distance from the lens to the image (v), and the focal length (f) are related by: 1/f = 1/u + 1/v. The formula of focal length for the measurement described above is: f ≈v
2. The f/# and NA are calculated from the aperture size (or Gaussian 1/e² beam width) and the focal length in air. Known ratios, together with the light wavelength, allow spot size calculations. This calc is accurate to ~2 significant figures
3. Use the actual focal length of the lens for depth of field calculations. The calculator will automatically adjust for any focal length multiplier or field of view crop for the selected camera. Focal lengths of digital camera lenses are listed here . Focus at the subject distance, 10 ft
4. f = Focal Length: NOTE: The sign convention used is as follows: if R 1 is positive, the first surface is convex, and if R 1 is negative, the surface is concave. The signs are reversed for the back surface of the lens: if R 2 is positive, the surface is concave, and if R 2 is negative, the surface is convex
5. Focal Length: The Effective Focal Length of your telescope is important to know; it is often listed on a label right on the telescope, sometimes as Fl, and usually in millimeters. It is equal to the Focal Ratio (f number) times the Objective Diameter. f Ratio: The Focal Ratio (f number) is the Focal Length divided by the Objective Diameter.
6. Real images occur when objects are placed outside the focal length of a converging lens (s>f). If the lens is converging but the distance from the object to the lens is smaller than the focal length, the image will be virtual. Diverging lenses always produce virtual images. This calculator shows a ray diagram when the image is real. Magnificatio
7. Free Parabola Foci (Focus Points) calculator - Calculate parabola focus points given equation step-by-step This website uses cookies to ensure you get the best experience. By using this website, you agree to our Cookie Policy

NOTE: If a calculated focal length is non-standard, select the nearest standard focal length and re-calculate projection distance and image size. These formulas will work in either feet/inches or metric. Just remember that aperture and focal length are in inches or millimeters and that projection distance and image width are in feet or meters Field Of View Calculator. For DSLR and SLR Cameras. To find the field of view (fov) for a camera lens or telescope enter the focal length (fl) and click the calculate button. You can select or convert the fov result format in either degrees-minutes-seconds format or decimal degrees below This calculator computes the lens focal length required to photograph an object of size y o at a distance x o, and produce an image of size y i on the film or sensor). The film or sensor plane is located at a distance x i.Distances x o and x i are measured, respectively, from the front and rear principal points of the lens. However, these points are rarely specified by lens manufacturers, and. This calculator is a first order calculator and is very useful for most machine vision applications*. NOTE: WD and FOV must be in the same units (e.g. in, ft, etc.). WD - Working Distance - distance from the front of the lens FOV - Field of View, width of picture FL - focal length of the lens The telescope dimensions are 130mm aperture and 650mm focal length. With the 2x Barlow lens (required to diverge the focus enough to mount the camera outside the optical tube assembly) it effectively becomes a telescope with 1300mm focal length. I can measure a picture of an object with known angular size (e.g. the moon) and use crop factors to.

### Video: 35mm Equivalent Focal Length Calculato

This calculator finds the maximum lens focal length and the appropriate minimum field of view, based on data entered for the CCD size, the distance from the lens to the object, and the maximum size of the target object to be imaged FOV (rectilinear) = 2 * arctan (frame size/ (focal length * 2)) Here frame size refers to the dimension of the frame in the direction of the FOV, so for 35mm (which is 24mm x 36mm), frame size is 36mm for the horizontal FOV, 24mm for the vertical FOV and 43.25mm for the diagonal FOV. Below is a calculator for FOV in both angular and linear terms

Calculation of the Focal Length of an Offset Satellite Dish Antenna http://www.john-legon.co.uk/offsetdish.htm[05.08.2013 15:00:32] Calculation of the Focal Length Angular Velocity Calculator (Radial Velocity) Aperture Area Calculator (Aperture Diameter) Aperture Area Calculator (Focal Length) Bernoulli Equation Calculator (Mass Flow Rate) Bernoulli Equation Calculator (Volume Flow Rate) Brewster's Angle Calculator; Buoyancy Calculator (Force) Buoyancy Calculator (Mass) Cylindrical Pipe Mass Flow Rate.

### Lens, Focal Length and Stereo Baseline Calculator - Nerian

Here is an easy to use calculator for these questions. Just enter the focal length of your lens, distance to your subject and selected f-stop, and see what happens. The calculator works both online and offline. focal length. mm System will calculate Focal Length: 2000 Input numbers with the following convention: Focal Length & Aperture: Do not use symbols to group digits together. (Good: 2032. Bad: 2,032 or 2.032) Focal Ratio (f/#): Use either one comma , or one period . symbol to indicate decimal point. (f/: 5.35 or 5,35 are the same Feb 14 2017. Focal length calculator math.In most telescopes the focal length is roughly equal to the length of the tube. The following calculator will do the math for you just enter the object size y o the image size y i the object distance x o and press the calculate button Here Holden is correct about The 20 mm focal length that DJI reports in the camera's specifications is the 35 mm equivalent focal length. The camera's actual focal length is significantly smaller than 20 mm because the camera's sensor is smaller than a standard 35 mm sensor Below is the DJI Phantom 4 pro photo details The Output from this Calculator. This camera field of view calculator provides three primary values: horizontal field of view, vertical field of view, and diagonal field of view. The calculator provides the equivalent EFL for a zero-distortion 35mm full frame type lens. For photographers, this can be used to visualize the resulting FoV

### Camera Lens Equivalent Focal Length Calculator • Fotometri

Focal Length. Your focal length will determine how far or close your frame is from your camera. At shorter focal lengths, like with wide-angle lenses, your frame will be much closer to the camera. Use a calculator. The easiest way to find your hyperfocal distance is to use the calculator listed below. You can do it in 3 easy steps If thin lenses are placed in contact, then the combined focal length of the lenses is related to its one of the focal lengths. Related formulas. Variables. f: Compound lens' focal length (m) f 1: Focal length of one of the lenses (m) f 2: Focal length of the other of the two lenses (m) Categories Effective focal length is essentially a combination of the two previous terms. The crop factor of the camera must be considered because it changes the effective focal length of the lens. In other words, a 50mm lens on a camera with a 1.5x crop factor has an effective focal length of 75mm. Calculating the Effective Focal Length All those focal lengths would have a minimum focus distance and the the maximum would be infinity. Think of these focal lengths as being magnification. Think of 35mm to 55mm to be about the same magnification as your eyes. 135mm would be like a telescope. 18mm would be wide angle and would be the opposite of magnification The closeup lens calculator Calculates the new macro magnification, new focal length when adding a closeup length, and its and its focal length as tube lens. Uses 1/newfl [new focal length of the combined two] = 1/fm + 1/fc, where f1 and f2 are respectively the main lens' and closeup filter's focal lengths. Focal length = 1000/diopters. Stacked.

### How To Calculate A Lens' Focal Length : Slightly

Output : Focal length of a lens is 1.92308 units . Attention reader! Don't stop learning now. Get hold of all the important mathematical concepts for competitive programming with the Essential Maths for CP Course at a student-friendly price. To complete your preparation from learning a language to DS Algo and many more, please refer Complete Interview Preparation Course To compare the focal lengths with a full frame camera sensor, you have to convert the number by 2. So a 25mm lens on a micro 4/3 sensor will result in the same image as a 50mm lens on a full frame sensor. Between the bracket, the focal length is given based on a full frame sensor camera. You will see the different effect of each focal length Focal Length: 360.0mm: Aperture: 60.0mm: Focal Ratio: 6.0 : Include 2-inch data: False: Table corrected for Paracorr: False: List only DIOPTRX eyepieces Sagitta to Focal Length Calculator. Did you buy a partially ground mirror at a swap meet and want to know it's focal length? Or perhaps you have been grinding your own piece of glass and want to know the current focal length. Just input the Sagitta (depth of curve) and Mirror Diameter, and this page will calculate the Focal Length, Focal Ratio.  Focal length; Aperture; Focus distance; Hyperfocal Distance and Depth of Field. When your lens is set at the hyperfocal distance, you're going to get the deepest depth of field possible for that focal length and aperture. From a few feet in front of you and all the way to the horizon (infinity), it's all gonna look sharp Focal length, usually represented in millimeters (mm), is the basic description of a photographic lens. It is not a measurement of the actual length of a lens, but a calculation of an optical distance from the point where light rays converge to form a sharp image of an object to the digital sensor or 35mm film at the focal plane in the camera Calculate focal length using image width by assuming field of view If you think about it, the field of view of most webcams should be similar because they expect you to be at a certain distance from the camera ( say a foot and a half ), and they would want the face to be a certain size ( not too large, not too small )