CN102073193A - Method for testing focal distance of camera lens by utilizing field angle - Google Patents

Abstract

The invention relates to the field of cameras, and provides a method for the focal distance of a camera lens by utilizing a field angle without detachment of the lens. The method comprises the following steps of: arranging the lens between a charge coupled device (CCD) panel and a test board, and focusing and regulating angles of the lens and the two ends of the test board to be theta; and making the target surface width of the CCD panel l, extending a distance of which the width is l' from the center of the test board to two ends, setting a focusing angle between the lens and the two ends of the test board with the distance of l', namely a field angle of the lens, setting a distance between the test board and the optical center of the lens as d and a distance between the optical center of the lens and the CCD panel, namely a focal distance of the lens as f, and obtaining the focal distance of the lens by utilizing the field angle through a formula.

Description

A kind of method of utilizing field angle test camera lens focal length

Technical field

The present invention relates to field of cameras, exactly is a kind of method of utilizing field angle test camera lens focal length.

Background technology

The traditional method of test camera lens focal length adopts the parallel light tube method of testing, its proving installation as shown in Figure 1, comprise eyepiece 1 ', eyeglass 2 ', parallel light tube 3 ', template 4 ' and light source 5 ', eyepiece 1 ' amplifies usefulness is observed in the back for eyes optics with the camera lens imaging, parallel light tube 2 ' mainly is the optical instrument that is used for producing parallel beam, wherein f ₁' be the measured lens focal length, f ' is a parallel light tube focal length measured value (being affixed on the parallel light tube tube wall), be known data, h is the spacing distance that is positioned at a pair of groove on the graticule of locating parallel light tube camera lens focal plane, its size also is in advance known, h is imaged on unlimited distance through behind the parallel light tube object lens, pass through tested eyeglass 2 ' again after, on its focal plane, obtain the picture h of h ₁The principle of this method is exactly by measuring as h ₁Size, then according to formula

Calculate the focal distance f of measured lens ₁'.Can not pull down after but the lens wearer that has installs, the method that then cannot adopt traditional parallel light tube to survey focal length obtains the focal length of camera lens.

Summary of the invention

At the problems referred to above, the present invention proposes a kind of method of utilizing field angle test camera lens focal length that needn't take lens wearer apart.

For solving this technical matters, the present invention takes following scheme: a kind of method of utilizing field angle test camera lens focal length, and realize by following step: camera lens is located between CCD plate and the test board, and the angle focusing at camera lens and test board two ends transfers to θ; CCD plate target surface width is 1, and the mind-set two ends extend that to get one section width be 1 ' distance from test board, and camera lens with test board apart from the focusing angle that is 1 ' two ends is

Be that the angle of view is

The distance at test board and lens optical center is d, and the distance of lens optical center and CCD plate is f, and promptly lens focus is f, and then lens focus is:

$f=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HSA00000364657700011.png"\; state="\{\{state\}\}">l</figure-callout>}}{2\mathrm{tg}\frac{\&PartialD;}{2}}$

Wherein, 1=1 ', and d＞＞f.

By adopting the aforementioned techniques scheme, the invention has the beneficial effects as follows: the present invention is located at camera lens between CCD plate and the test board for a kind of method of utilizing field angle test camera lens focal length, and wherein 1 be the target surface width of known CCD plate, only needs the measurement field angle Numerical value, need not to pull down camera lens and take out eyeglass, can calculate the size of focal distance f by formula.

Description of drawings

Fig. 1 is the synoptic diagram of known parallel light tube method of testing;

Fig. 2 is the synoptic diagram of the principle of the invention.

Embodiment

Now the present invention is further described with specific embodiment in conjunction with the accompanying drawings.

With reference to figure 2, present embodiment discloses a kind of method of utilizing field angle test camera lens focal length, and realize by following step: adopt 1/3 inch CCD plate 4, its target surface is of a size of wide 4.8mm, high 3.6mm, diagonal line 6mm; Camera lens 2 is located between CCD plate 4 and the test board 3, and camera lens 2 transfers to θ with the angle focusing at test board 3 two ends; CCD plate 4 target surface width are 1, and wherein 1 is 4.8mm, and the mind-set two ends extend that to get one section width be 1 ' distance from test board 3,1=1 '=4.8mm wherein, and camera lens 2 and test board 3 distances are that the focusing angle at 1 ' two ends is

Be that camera lens 2 field angle are Test board 3 is d with the distance of camera lens 2 optical centres, and the distance of camera lens 2 optical centres and CCD plate 4 is f, and promptly the focal length of camera lens 2 is f, and d＞＞f.Then can utilize following formula to calculate the focal length of camera lens 2:

$f=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HSA00000364657700011.png"\; state="\{\{state\}\}">l</figure-callout>}}{2\mathrm{tg}\frac{\&PartialD;}{2}}$

The present invention is located at camera lens between CCD plate and the test board for a kind of method of utilizing field angle test camera lens focal length, and wherein 1 be the target surface width of known CCD plate, only needs the measurement field angle

Numerical value, need not to pull down camera lens and take out eyeglass, can calculate the size of focal distance f by formula.

Claims (1)

1. method of utilizing field angle test camera lens focal length, it is characterized in that realizing by following step: camera lens is located between CCD plate and the test board, and the angle at camera lens and test board two ends is focused and is transferred to θ; CCD plate target surface width is 1, and the mind-set two ends extend that to get one section width be 1 ' distance from test board, and camera lens with test board apart from the focusing angle that is 1 ' two ends is

Be that the angle of view is

The distance at test board and lens optical center is d, and the distance of lens optical center and CCD plate is f, and promptly lens focus is f, and then lens focus is:

$f=\frac{l}{2\mathrm{tg}\frac{\&PartialD;}{2}}$

Wherein, 1=1 ', and d＞＞f.

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