CN212341573U - Middle focus video lens with focal length of 35mm - Google Patents
Middle focus video lens with focal length of 35mm Download PDFInfo
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- CN212341573U CN212341573U CN202021402651.0U CN202021402651U CN212341573U CN 212341573 U CN212341573 U CN 212341573U CN 202021402651 U CN202021402651 U CN 202021402651U CN 212341573 U CN212341573 U CN 212341573U
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Abstract
The utility model discloses a middle focus video lens with a focal length of 35mm, which comprises a first lens group, an iris diaphragm, a second lens group and a third lens group from the object side to the image side in sequence; the first lens group has positive focal power and is fixed in position, the second lens group has negative focal power and is fixed in position, the third lens group has positive focal power, the position can move along the optical axis direction to be focused, the first lens group comprises a negative lens group, the negative lens group comprises at least two negative lenses, the second lens group comprises a positive cemented lens and a negative cemented lens, the third lens group comprises a negative and positive cemented lens, the lens can improve the light transmission amount, can effectively correct chromatic aberration and distortion, and improves resolution and definition.
Description
Technical Field
The utility model relates to a lens technical field, in particular to focus video camera lens in 35 mm's of focus.
Background
With the rise of video shooting in recent years and the vigorous development of the video industry, the demand of video lenses is more and more large, but the light transmission amount of the existing video shooting is low, distortion is easy to generate, object distortion is caused, the definition of a picture is influenced, and the resolution of an edge field is low.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a focus 35 mm's well burnt video camera lens, first lens are equipped with negative lens group and can improve the light flux volume to the camera lens is equipped with the cemented lens combination, can effectively correct colour difference and distortion, improves resolution ratio and definition, and it is higher to have solved present well burnt video camera lens distortion degree, the relatively poor problem of resolution ratio.
To achieve the purpose, the utility model adopts the following technical proposal:
a middle focus video lens with a focal length of 35mm sequentially comprises a first lens group, an iris diaphragm, a second lens group and a third lens group from an object side to an image side;
the first lens group has positive focal power and is fixed in position;
the second lens group has negative focal power and is fixed in position;
the third lens group has positive focal power, and the position can move along the direction of the optical axis for focusing;
the first lens group comprises a negative lens group, and the negative lens group comprises at least two negative lenses;
the second lens group comprises a positive cemented lens and a negative cemented lens;
the third lens group comprises a negative and positive cemented lens;
the first lens group, the second lens group and the third lens group satisfy the following formula:
-1.5<f1/f2<1；-0.75<f3/f1<0.8；
where f1 represents a focal length value of the first lens group, f2 represents a focal length value of the second lens group, and f3 represents a focal length value of the third lens group.
Therefore, the focal power of the first lens group and the second lens group meets the specific relation of-1.5 < f1/f2<1, enough rear working distance can be ensured, the normal use requirement is met, the focal power of the third lens group and the first lens group meets the specific relation of-0.75 < f3/f1<0.8, the bearable view field angle of the system can be ensured, the phase difference correction of the whole view field is facilitated, the first lens is provided with the negative lens group, the light flux can be increased, the relatively short close-range shooting distance is realized, the second lens group and the third lens group are provided with the matched cemented lens, the chromatic aberration and the distortion can be corrected, the distortion is reduced, and the resolution ratio is improved.
In some embodiments, the refractive index of the first lens group including at least one lens is between 1.8 and 2.0.
Thus, the plurality of lenses are set to a high refractive index to realize a compact optical structure, and the fourth lens is preferably provided.
In some embodiments, the abbe number of the second lens group including at least one lens is between 80 and 90.
Thus, the plurality of lenses are set to a high abbe number, which is advantageous for reducing dispersion, and the fifth lens is preferably provided.
In some embodiments, the third lens group comprises at least one lens with a refractive index between 1.85 and 2.0.
Thus, a plurality of lenses are provided with a high refractive index to realize a compact optical structure, and a tenth lens is preferably provided.
In some embodiments, the second lens group and the third lens group can constitute a double-gauss-like optical path structure.
Thus, the double-Gaussian-like optical path structure is beneficial to correcting the distortion.
In some embodiments, the back working distance of the lens is BFL, the focal length of the lens is f, and the following equation is satisfied: 0.85< BFL/f < 1.78. Therefore, the sufficient rear working distance is ensured, and the working requirement is met.
In some embodiments, a mirror surface of the first lens group is curved toward the object side.
From this, the mirror surface of first lens is crooked to the object side, and is the crescent, does benefit to the increase visual field, improves the luminous flux, improves marginal visual field resolution ratio.
In some embodiments, the total length of the first mirror to the last mirror of the lens is between 40 and 76.5 mm, and the maximum aperture of the lens is between 20 mm and 30 mm. Therefore, the lens is compact in structure, small in size, light and convenient to use.
The utility model has the advantages that: the first lens is provided with a crescent negative lens, so that a large field angle can be realized, and the back focal length can be effectively increased;
and the second lens group and the third lens group are provided with two cemented lenses which are matched with each other, and can form a quasi-double-Gaussian light path, so that the coma aberration, astigmatism, chromatic aberration and distortion of the front lens group and the rear lens group can be effectively balanced, the matching tolerance sensitivity of the front lens group and the rear lens group is greatly reduced, and the resolution of the system is improved.
Drawings
Fig. 1 is a structural diagram of a middle focus video lens with a focal length of 35mm according to the present invention;
fig. 2 is an axial coloring differential view of a mid-focus video lens with a focal length of 35mm according to the present invention;
fig. 3 is a schematic vertical axis chromatic aberration diagram of a middle focus video lens with a focal length of 35mm according to the present invention;
fig. 4 is a schematic view of field curvature distortion of a mid-focus video lens with a focal length of 35mm according to the present invention;
fig. 5 is a schematic diagram of light aberration of a mid-focus video lens with a focal length of 35mm according to the present invention;
fig. 6 is a schematic diagram of a diffuse spot of a mid-focus video lens with a focal length of 35mm according to the present invention;
fig. 7 is a schematic MTF diagram of a mid-focus video lens with a focal length of 35mm according to the present invention;
fig. 8 is a schematic view of MTF and field of view of a mid-focus video lens with a focal length of 35mm according to the present invention;
wherein: g1-first lens group; g11-negative lens set; g2-second lens group; g3-third lens group; l1-first lens; l2-second lens; l3-third lens; l4-fourth lens; l5-fifth lens; l6-sixth lens; l7-seventh lens; l8-eighth lens; l9-ninth lens; l10-tenth lens.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Referring to fig. 1, a mid-focus video lens having a focal length of 35mm includes, in order from the object side to the image side, a first lens group G1, an iris STO, a second lens group G2, and a third lens group G3;
the first lens group G1 has positive refractive power and is fixed in position;
the second lens group G2 has negative focal power and is fixed in position;
the third lens group G3 has positive power, and the position can be moved in the optical axis direction for focusing;
the first lens group G1 includes a negative lens group G11, and the negative lens group G11 includes at least two negative lenses;
the second lens group G2 includes positive and negative cemented lenses;
the third lens group G3 includes a negative positive cemented lens;
the first lens group G1, the second lens group G2 and the third lens group G3 satisfy the following formula:
-1.5<f1/f2<1；-0.75<f3/f1<0.8；
where f1 represents a focal length value of the first lens group G1, f2 represents a focal length value of the second lens group G2, and f3 represents a focal length value of the third lens group G3.
In a further illustration, the refractive index of the first lens group G1 includes at least one lens in the range of 1.8 to 2.0.
In further detail, the second lens group G2 includes at least one lens with abbe number between 80 and 90.
In a further description, the third lens group G3 includes at least one lens with a refractive index between 1.85 and 2.0.
Further, the second lens group G2 and the third lens group G3 can constitute a double-gauss-like optical path structure.
Further, the back working distance of the lens is BFL, the focal length of the lens is f, and the following equation is satisfied: 0.85< BFL/f < 1.78.
Further, the mirror surface of the first lens L1 of the first lens group G1 is curved toward the object side.
Further, the total length of the first mirror surface to the last mirror surface of the lens is between 40 and 76.5 mm, and the maximum aperture of the lens is between 20 mm and 30 mm.
The working principle is as follows:
the video lens includes a first lens group G1, a second lens group G2, and a third lens group G3, wherein the third lens group G3 is movable in the optical axis direction to perform focusing and magnification-varying.
The first lens group G1 includes, in order from the object side to the image side, a first lens L1 with negative power, a second lens L2 with negative power, a third lens L3 with positive power, and a fourth lens L4 with positive power, wherein the first lens L1 and the second lens L2 form a negative lens group G11, and the mirror surface of the first lens L1 is curved toward the object side and is crescent-shaped, so that a large field angle and a light transmission amount can be realized, and a back focal length can be effectively increased.
The second lens group G2 is a positive and negative cemented lens formed by a positive power fifth lens L5 cemented with a negative power sixth lens L6.
The third lens group G3 includes, in order from the object side to the image side, a seventh lens L7 with negative power, an eighth lens L8 with positive power, a ninth lens L9 with positive power, and a tenth lens L10 with positive power, wherein the seventh lens L7 and the eighth lens L8 are cemented into a cemented lens, and the cemented lens is capable of correcting chromatic aberration and distortion in cooperation with the cemented lens of the second lens group G2.
In addition, the second lens group G2 and the third lens group G3 make the optical path substantially similar to a double-gauss optical path, that is, the optical path is diffused first, then diffused, then polymerized, and then polymerized, so that the lens combination structure can effectively balance coma, astigmatism, chromatic aberration and distortion of the front and rear lens groups, so that the matching tolerance sensitivity of the front and rear lens groups is greatly reduced, and the resolution of the system is improved.
A planar tenth lens L10 is disposed close to the image side.
The first lens group G1 and the second lens group G2 can be provided with a plurality of lenses with high refractive index, so that the total length of an optical path can be effectively shortened, and the number of the lenses can be reduced.
The second lens group G2 can be provided with a plurality of lenses having a high abbe number, thereby reducing dispersion, reducing distortion, and improving resolution.
Referring now to Table one, numerical data for some embodiments, such as radius of curvature, thickness, refractive index, Abbe number, etc. of the lens are shown, where S1-S21 represent the mirror surface of the lens from the object side to the image side, and the numerical data are typically in "mm" units.
Table one:
| radius of curvature | Thickness of | Refractive index | Coefficient of dispersion | ||
| S1 | 73.8 | 1 | 1.65 | 37 | |
| S2 | 25 | 7.2 | |||
| S3 | -36.022 | 6.42 | 1.72 | 52 | |
| S4 | 235 | 1 | |||
| S5 | -250 | 5.8 | 1.78 | 52 | |
| S6 | -35.658 | 0.2 | |||
| S7 | 27.165 | 5.55 | 1.80 | 46.5 | |
| S8 | 230.051 | 15.35 | |||
| STO | Infinity | 1.25 | |||
| S10 | 32.874 | 4.5 | 1.5 | 81.5 | |
| S11 | -16.156 | 1 | 1.63 | 34.2 | |
| S12 | 23.333 | 8.25 | |||
| S13 | -15.105 | 1 | 1.7 | 35 | |
| S14 | 120.555 | 5 | 1.62 | 57 | |
| S15 | -18.7 | 0.2 | |||
| S16 | -138.292 | 3.5 | 1.72 | 52 | |
| S17 | -35.155 | 0.2 | |||
| S18 | 78 | 8 | 1.88 | 40 | |
| S19 | -85 | 26 | |||
| | Infinity | 2 | 1.52 | 64.5 | |
| | Infinity | 2 | |||
| IMAGE | Infinity |
Fig. 2 is a diagram of spherical aberration on an axis according to an embodiment of the present disclosure, fig. 1 is a diagram of vertical axis chromatic aberration according to an embodiment of the present disclosure, and fig. 4 is a diagram of field curvature distortion according to an embodiment of the present disclosure. Fig. 5 is a light aberration diagram according to the embodiment of the disclosure, fig. 6 is a diffuse speckle diagram according to the embodiment of the disclosure, fig. 7 is an MTF diagram according to the embodiment of the disclosure, and fig. 8 is an MTF and field diagram according to the embodiment of the disclosure. From above-mentioned chart, this disclosed camera lens can realize the intermediate focal length, can compromise the full field of view high definition of low distortion, can realize the little volume of big clear aperture, low distortion, and the aberration is rectified well, can all reach better formation of image effect at the full field of view.
What has been described above are only some embodiments of the invention. For those skilled in the art, without departing from the inventive concept, several modifications and improvements can be made, which are within the scope of the invention.
Claims (8)
1. A mid-focus video lens having a focal length of 35mm, comprising, in order from an object side to an image side, a first lens group (G1), an iris, a second lens group (G2), and a third lens group (G3);
the first lens group (G1) has positive focal power and is fixed in position;
the second lens group (G2) has negative focal power and is fixed in position;
the third lens group (G3) has positive focal power, and the position can be moved along the optical axis direction for focusing;
the first lens group (G1) comprises a negative lens group (G11), the negative lens group (G11) comprises at least two negative lenses;
the second lens group (G2) comprises a positive cemented lens and a negative cemented lens;
the third lens group (G3) includes a negative positive cemented lens;
the first lens group (G1), the second lens group (G2), and the third lens group (G3) satisfy the following formula:
-1.5<f1/f2<1；-0.75<f3/f1<0.8；
wherein f1 represents a focal length value of the first lens group (G1), f2 represents a focal length value of the second lens group (G2), and f3 represents a focal length value of the third lens group (G3).
2. The mid-focus 35mm focal length video lens according to claim 1, wherein the refractive index of the first lens group (G1) comprising at least one lens is between 1.8 and 2.0.
3. The mid-focus video lens with the focal length of 35mm as claimed in claim 1, wherein the abbe number of the second lens group (G2) comprising at least one lens is between 80 and 90.
4. The mid-focus 35mm focal length video lens of claim 1, wherein the refractive index of the third lens group (G3) comprising at least one lens is between 1.85 and 2.0.
5. The mid-focus 35mm focal length video lens of claim 1, wherein the second lens group (G2) and the third lens group (G3) are capable of forming a double Gaussian-like optical path structure.
6. The mid-focus video lens with a focal length of 35mm as claimed in claim 1, wherein the back working distance of the lens is BFL, the focal length of the lens is f, and the following equation is satisfied: 0.85< BFL/f < 1.78.
7. The mid-focus 35mm focal length video lens according to claim 1, wherein the first lens (L1) of the first lens group (G1) has a mirror surface curved toward the object side.
8. The lens of claim 1, wherein the total length of the first mirror to the last mirror of the lens is between 40 mm to 76.5 mm, and the maximum aperture of the lens is between 20 mm to 30 mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202021402651.0U CN212341573U (en) | 2020-07-16 | 2020-07-16 | Middle focus video lens with focal length of 35mm |
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| CN202021402651.0U CN212341573U (en) | 2020-07-16 | 2020-07-16 | Middle focus video lens with focal length of 35mm |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111694131A (en) * | 2020-07-16 | 2020-09-22 | 北创光电科技(邵阳)有限公司 | Middle focus video lens with focal length of 35mm |
| CN111694131B (en) * | 2020-07-16 | 2024-05-31 | 北创光电科技(邵阳)有限公司 | Medium-focus video lens with focal length of 35mm |
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2020
- 2020-07-16 CN CN202021402651.0U patent/CN212341573U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111694131A (en) * | 2020-07-16 | 2020-09-22 | 北创光电科技(邵阳)有限公司 | Middle focus video lens with focal length of 35mm |
| CN111694131B (en) * | 2020-07-16 | 2024-05-31 | 北创光电科技(邵阳)有限公司 | Medium-focus video lens with focal length of 35mm |
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