Formula for focal length of a lens

Lens combination formulas - EFFECTIVE FOCAL LENGTH

The following formulas show how to calculate the effective focal length and principal-point locations for a combination of any two arbitrary components. The approach for more than two lenses is very simple: Calculate the values for the first two elements...

Experiment 6 - optics: focal length of a lens

3. Diverging (negative) lens. (d) A lens which converges a bundle of parallel rays is called a converging lens, or positive lens (its focal length is taken as positive.)


An important advantage of giving the focal length of a diverging lens as a negative number is that it makes the formulas work out automatically. For instance, if you combine a converging lens with 10 cm focal length with a diverging lens of...

Lab 2 - c. Focal length of negative lenses

1. Gaussian Lens Formula. (2.1). where f is the focal length of a thin lens. f > 0 for a convex (converging) lens and f < 0 for a con-cave (diverging) lens. so and si are the distances between the central plane of the lens and an ob-ject and its image, respectively.

formula for optimal focal length of... - Photography Forums

Usually I was calculating the pinhole according the focal length and using Lord Rayleigh´s formula but since I know my pinhole size I wanted to know if I can

Focal Length of Eyeglasses - The Physics Factbook

The formula for determining the focal length of any lens is: 40/D. = inches of the focal length.

Focal Length of a Diverging Lens - Physics Forums

The magnitude of the focal length of the lens is 20.0 cm. Find the image position and size.

Focal Length of a Lens

The principal focal length of a lens is determined by the index of refraction of the glass, the radii of curvature of the surfaces, and the medium in which the lens resides. It can be calculated from the lens-maker's formula for thin lenses.


Focal length is the distance at which a lens focuses parallel rays of light.

How to use the Thin Lens Formula to model a thick... --

The internet is full of formulas for converting between 'angle of view' and 'focal length', but what most don't disclose is that these calculations are

Stopping Camera Shake and the 1/(Effective Focal Length) Formula

The "effective focal length multiplier" formula is, by all accounts, an arbitrary value in the camera shake negating formula. In the above scenario, we multiplied the lens' focal length by 1.6 (the crop factor arrived at by comparing the 60D's sensor size to that of a full-frame camera).

Lens focal length calculator

These equations use the focal length f of the lens, which is a characteristic of the lens and is usually expressed in millimeters.

Solved: Lens Maker's Formula... -

This relation always gives a negative focal length f as expected for a double concave lens (because it is a diverging lens). Consider such a lens composed of quartz with R1 = R2 = 29 cm and n = 1.54 for blue light.

Is there any formula to find the focal length of a lens? - Quora

If the lens is constructed of homogeneous material of constant refractive index with centered spherical surfaces, then. The formula for the focal length of a lens in a vacuum is given by

Gaussian lens formula

The formula for field of view is shown in the lower-left corner of the applet, and the field of view for your current slider settings is shown in the

Lens Experiment - Focal Length

Theory. A key formula when working with lenses is the Thin-Lens Equation: where f is the focal length of the lens, do is the object distance and di is the image distance.


f = 1/D f = focal length in metre D = lens power in dioptres, - for concave lens and + for convex lens. Vergence formula.

Formula for adjusting Focal Length with Close-up Lenses - Forum

Anyone know of a formula -- or other way -- to calculate the "new" focal length when you add a close-up or supplementary filter/lens to a given lens? I know that a CU lens has its own focal length and it will shorten the focal length of the lens...

Question 1: Calculate the focal length of a lens whose refractive index...

Lens maker's formula helps to construct a lens with specified focal length.

Spherical Lenses

The center rays, on the other hand, are coming to a focus behind the film plane; when the lens is stopped down, only those (out of focus) center rays are left. On the remainder of this page, we'll find an exact formula for the focal length of a spherical lens...

Measuring Focal Length

focal length = (d)/((m-(1/m)). Example: Lets say the magnification was 6x and the distance the lens had to be moved was 345mm.

For a lens ... 1/image distance + 1/object distance = 1/focal length of...

A very simple method to calculate the focal length of a lense is to focus it front of the sun and find out a sharp, small point at ground and you have to

Chapter 36 - Lenses - Object at Focal Length F

Converging and Diverging Lens. The Focal Length of Lenses. The Principal Focus.

How Does Lens Thickness Affect Focal Length? - Sciencing

A lens surface that is concave to the outside is a diverging lens with a negative focal length.

Focal Length of a Lens

German: Brennweite. Category: general optics. Formula symbol: f. Units: m. How to cite the article; suggest additional literature.

Methods for measuring a lens focal length

The focal length is one of the most important parameter of a lens.

Macro photograpy calculators, including extension tube, stacked lens...

This is a formula for a thin lens, but still works, although for complex zoom and/or inner focus lenses it is less precise.

Lens Focal Length Calculator - Applying The Lens Formula

Focal Lengths: As rays of light enter a camera through its lens they converge to a point of focus some distance behind the lens.

Thin Lens- Concave and Convex Lenses - Formula

Thin Lens Formula with Magnification for Concave and Convex Lenses. First of all, what is a thin lens?

PhysicsLAB: Determining the Focal Length of a Converging Lens

5. Use the thin lens formula or equivalently, , along with your measured values for so and si to calculate the focal length of your lens. Show your work on this paper and record your values in the table below.

Effective Focal Length - Rod Lenses

Effective Focal Length. A lens forms an image of the source on a target on which it is focused at an appropriate distance away.

Lenses. Field of view and focal length

The focal length of a lens is an inherent property of the lens, it is the distance from the center of the lens to the point at which objects at infinity focus.

Focal length drops out of the Bercovitz infinity formula and...

Wattie magnification formula. Stereo base, not focal length of the lens, determines magnification. A stereoscopic photography paradox, when stereoscopic infinity is in the picture. 1/30 rule for stereo pairs: mathematics of the 2 meter stereo window.

Focal Length and Magnification of a Thin Lens by Michel Najm on Prezi

Converging lens of known focal length1: 100mm and 200mm. Screen: to receive the image created by the light source.

Optical formulas - Focal length of lens with close-up lens

The formula for G is only an approximation for the real relationship and is only accurate enough for large distances (i. e. d >> f). Many modern photo lenses use internal focusing, and with that the focal length changes with the focus distance.

Concave Lens - Focal Length (Theory) : Class 12... : Amrita Online Lab

Since a concave lens will not produce a real image, a convex lens is used to measure its focal length. There are two methods to find the focal length of a concave lens.

Equivalent Focal Length and Field of View

Focal length is an optical attribute of a lens, which has nothing to do with the camera or the type of sensor it uses.

To find the focal length of a concave lens using... - Learn CBSE

A Short Description about the Arrangement As a concave lens always forms a virtual image, its focal length can not be found directly as for a convex lens.

Thiery Legault - How to adjust the focal length ?

Once the resultant focal length of the telescope is chosen, the amplification factor must be adjusted to reach this value, by changing the distance between the Barlow lens and the focal plane. The formula can be reversed to obtain D from A and FB: D = FB (A - 1).

Derive the formula for combined focal length of two lenses, when...

0. Consider two lenses L1 and L2 separated by a small distance 'd' apart, as shown below. A ray of light AB initially parallel to the principal axis hits the lens L1 and deviates and then hits lens L2.

Lens Focal Length and Field of View

The calculator below converts between the focal length f and the field of view (FOV) of a rectilinear lens. The formula that it implements is FOV = 2 arctan (x / (2 f)), where x is the diagonal of the film. The FOV is measured across the frame's diagonal...

Angle of View - Focal Length

Select the best suited lens for optimum performance in each application. Focal Length. Rays from infinitely distance objects are condensed internally in the lens at a common point on the optical axis.

Focal length - does this change when a camera focuses? - Forum

The focal length of some lenses changes significantly with focus though - e.g., Canon 100mm macro is apparently closer to 70mm when it's at minimum focus.

To Determine the Focal Length of a Convex Lens. - A-Level Science

I have obtained a formula for this: - 1 + 1 = 1 or 1 = -1 + P U V F U V AND Problems that might arise: In this experaments there might be a number of problems.

Lens Focal Lengths for Common Situations :: Digital Photo Secrets

Longer focal lengths, like those found on a telephoto lens, provide a narrower angle of view with greater magnification. If your lens is marked with a focal length range, like 18-105mm this means it is a zoom lens capable of a range of different focal lengths.

How to Find the Focal Length of a Lens

f is the focal length of the lens, do is the distance of the object from the lens, and di is the distance of the image formed by the lens. Lens Formula Sample Problem. Let's say your teacher gave you this problem

Focal Length of Convex Lens Experiment - A Plus Topper

Definition: The equation relating the object distance (u), the image distance (v) and the focal length (f) of the lens is called the lens formula.

Camera Sensor Crop Factor and Equivalent Lens Focal Length.

The Focal Length of the lens is as marked, 50 mm. The sensor crop factor cannot change the physical lens focal length.

Focal Length of Lenses

Objective: To measure the focal length of convex (positive or convergent) lenses and concave (negative or divergent) lenses.

Formula for finding focal length

When the lens focuses on infinity, the focal length of a lens is fixed.

Focal Length - Finding a Lens Example

Focal length is measured in millimeters (mm) and it represents the distance from the optical center of a lens to the digital camera sensor when the subject of the photo is in focus. This is the standard textbook definition...

What is Focal Length of a Lens and How to Use It to Your Advantage

The focal length of a lens determines the magnification and compression of a scene.

Name - Table 1: Lens-screen distance for distant

Table 7: Focal length from the compound lens formula. Lens or Lens Combination: RG.

Physics 6C

The power of a lens (units are called DIOPTERS) is just the reciprocal of the focal length, in meters.

Diopter and Lens Power

In fact, it is usually referred to as lens power. Normally, the focal length of a lens uses millimeter as a unit such as 50mm, 100mm, 8.9mm and

Abridged Formula For Reference. Positive Lens

If f represents the focal length of an ordinary positive lens, nf any multiple of it, By the law of conjugate foci: f2 =xy.(1) where x=nf, and y=1/nf.

Lens Focal Length - Photography Know How

Focal length is a term that refers to the optical length of a lens.

Lenses - 6.2 Focal Length of Concave Lens

6.1 Focal Length Of Convex Lenses. Check that the laser beam is parallel to the axis of the optical bench by letting the laser beam hit a mark on the screen, and then moving

Rearrange Formula Focal Length Object Image Length Reciprocals

Determination of the Focal Length of a Convex Lens UV Method - Продолжительность: 2:38 TutorVista 125 785 просмотров.

focal length of converging glass lens in water... - Wyzant Resources

Find its focal length when it is immersed in water, which has an index of refraction: nw = 1.33.


Focal length is the distance at which a lens focuses parallel rays of light.

Magnifying Power and Focal Length of a Lens -

Calculate the magnifying power of each magnifying lens. Use the following formula. Where Mp is Magnifying power, LDDV is the least distance of distinct vision you found in step 7, and Lf is the focal length of the lens.

DSLR Camera Basics: Understanding Focal Length

Learn the effects of a camera lens' focal length to help you choose the right lens for a particular scene and your photography style.

Focal Length Equation - Formula & Problems

The focal length formula helps to determine the focal length in both concave and cave lenses.

Focal Length Definition - Photography Glossary - SLR Lounge

This next diagram is also inaccurate compared to the actual optical formula of the particular lens, however it depicts the general concept of a multi-element


a formula for the focal lengths and aberrations of a lens of uniaxal crystal bounded by any two infinitely near surfaces, which have the optical axis of the crystal for their common axis of revolution: all cases of cusps or other singular curvatures at the common vertex being set aside.

Focal Length and F-Stop Explanation - Lens Focal Length Chart

Very simply, it is the distance from the lens to the film, when focused on a subject at infinity. In other words, focal length equals image distance for a far subject.

Fundamental - Example 1: Object outside Focal Point

To determine the appropriate focal length, set the spherical aberration formula for a plano-convex lens equal to the source (spot) size

Focal Length Multiplier Explained

That's important because the focal length of a lens is based on that full frame 35mm format.