50mm Archives - CanonWatch

Canon Patent: 24-70mm f/4, 28-200mm f/2.8-5.6, 20-60mm f/2.8-4 And 50mm f/1.4 (composite opticals)

March 22, 2024
Canon Patents
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A new Canon patent application for RF-mount lenses with composite optical elements.

Canon patent 2024039231 (Japan, published 3/22/2024) discusses optical formulas and methods for four lenses with composite optical elements:

24-70mm f/4
28-200mm f/2.8-5.6
20-60mm f/2.8-4
50mm f/1.4

Guess the most interesting of the bunch is the 50mm f/1.4 lens. From the patent literature:

An object of the present invention is to provide a composite optical element that is small and lightweight and has high optical performance.
BACKGROUND ART: In recent years, there has been an increasing demand for shorter overall length and lighter weight of photographic optical systems. In order to reduce the overall length and weight of the photographic optical system, there is a method of increasing the refractive power of each lens and introducing an aspherical lens to correct various aberrations that occur as a result.
As an aspherical lens for a photographic optical system, there is a composite element formed by molding a resin layer onto a glass lens.
Composite elements have a high degree of freedom in selecting the glass material for the glass lens, and are easy to mold, so they are characterized by being easy to introduce into photographic optical systems.
Patent Document 1 discloses an optical system in which chromatic aberration is corrected by using a material with a low partial dispersion ratio for the glass of a composite lens and combining it with a resin having a high partial dispersion ratio. If resin is used as an aspherical lens, chromatic spherical aberration and chromatic curvature of field will increase, which is undesirable.
Accordingly, an object of the present invention is to provide a composite optical element that is small and lightweight and has high optical performance.

Example 1

Focal length: 24-67.90
F value: 4.12
Half angle of view: 41.33-17.67
Image height: 19.39-21.64
Total length: 108.50-142.13
Back focus: 20.95-50.49

Example 2

Focal length: 15.30-45.00
F value: 4.12
Half angle of view: 41.68-16.51
Image height: 11.60-13.65
Total length: 83.50
Back focus: 17.67

Example 3

Focal length: 50.03
F value: 1.44
Half angle of view: 23.39
Image height: 21.64
Total length: 113.51
Back focus: 13.51

Example 4

Focal length: 28.40-197.00
F value: 2.90-5.70
Half angle of view: 37.30-6.27
Image height: 18.97-21.64
Total length: 151.14-220.00
Back focus: 13.50-47.04

Example 5

Focal length: 21.00-60.00
F value: 2.90-4.10
Half angle of view: 45.79-19.29
Image height: 18.37-21.62
Total length: 135.70-126.50
Back focus: 22.43

Example 6

Focal length: 390.03-275.02
F value: 2.91-3.08
Half angle of view: 3.21-4.52
Image height: 21.84-21.72
Total length: 347.00
Back focus: 46.20

More Canon patents are listed here.

[via asobinet]

Canon Patent: 50mm f/4 IS Macro And 90mm f/4 IS Macro

January 25, 2024
Canon Patents
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Canon patent application 2024010559 (Japan, published 01/24/2024) discusses optical formulas for two macro lenses for the RF mount:

50mm f/4 IS Macro
90mm f/4 IS Macro

From the patent literature:

An object of the present invention is to provide a compact and high-performance optical system in a macro lens, in which a focus lens group is made lighter and smaller, achieving higher focus stop precision and faster focusing speed.
BACKGROUND ART
A macro lens is known as a lens capable of close-up photography. In recent years, there has been a demand for a macro lens that has high optical performance with little aberration variation in the entire focus region.
Patent Documents 1 and 2 disclose macro lenses that correct aberration fluctuations during focusing by moving a large focus lens group during focusing.
However, in the macro lenses described in Patent Documents 1 and 2, the actuator becomes large in order to move a large focus lens group, and the focus lens group becomes large, resulting in a decrease in focus stop accuracy and focus speed. There was a problem.
The present invention provides a compact and high-performance optical system in a macro lens by reducing the weight and size of the focus lens group, achieving high focus stop precision and high speed focusing speed.

Example 1

Focal length: 111.29
F value: 4.12
Half angle of view: 11.00
Image height: 21.64
Total length: 125.00
Back focus: 34.03
Magnification: 1.0

Example 2

Focal length: 90.00
F value: 4.12
Half angle of view: 13.52
Image height: 21.64
Total length: 120.00
Back focus: 21.58
Magnification: 1.0

Example 3

Focal length: 110.00
F value: 4.12
Half angle of view: 11.13
Image height: 21.64
Total length: 119.99
Back focus: 43.07
Magnification: 0.5

Example 4

Focal length: 52.00
F value: 4.12
Half angle of view: 22.59
Image height: 21.64
Total length: 115.00
Back focus: 24.18
Magnification: 1.0

Canon Patent: 24mm F1.4, 35mm F1.4 And 50mm F1.4

August 30, 2023
Canon Patents
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And yet another Canon patent application. Fast primes for the RF mount.

Canon patent application 2022024113 (japan, published 8/30/2023) discusses optical formulas for three fast prime lenses:

24mm F1.4
35mm F1.4
50mm F1.4

From the patent literature:

Optical system and imaging device

A compact optical system capable of high-speed focusing with a wide angle of view and a large aperture ratio is provided.

Description of the Related Art

Imaging devices using solid-state imaging devices such as CCD sensors and CMOS sensors are required to have optical systems that have a wide angle of view, a large aperture ratio, a small size, and high optical performance. There is also a demand for high-speed autofocus in the optical system.

An optical system with a wide angle of view and a large aperture ratio has the problem that it is difficult to correct various aberrations. In particular, if the weight of the focus lens group is reduced in order to perform high-speed focusing (autofocus), it becomes difficult to suppress aberration fluctuations in focusing from an object at infinity to a close object.

According to the present invention, it is possible to provide a compact optical system capable of high-speed focusing while having a wide angle of view and a large aperture ratio.

Example 1 (24mm F1.4)

Focal length 24.36
F value 1.44
Half angle of view 41.61
Image height 21.64
Lens length 106.56
Back focus 12.72

Example 2 (35mm F1.4)

Focal length 34.09
F value 1.45
Half angle of view 32.40
Image height 21.64
Lens length 113.84
Back focus 13.67

Example 3 (50mm F1.4)

Focal length 48.50
F value 1.45
Half angle of view 24.04
Image height 21.64
Lens length 108.70
Back focus 11.47

More Canon patents are listed here.

[via Digicame Info]

Yongnuo Might Soon Release Another RF Mount Lens, The YN 50mm F1.8R DF DSM

August 11, 2023
News
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After the YN 85mm F1.8R DF DSM, Yongnuo might soon release a second lens for the RF mount.

It seems the YN 50mm F1.8R DF DSM has been displayed at P&I Shanghai (image on top). No information about the release to the general public and about the specifications.

[via asobinet]

Canon Recalls Some Batches Of EOS R10 Cameras And EF 50mm F1.2 Lenses

March 30, 2023
Canon News
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Canon Japan published a customer advice about some batches of Canon EOS R10 cameras and EF 50mm f/1.2L lenses.

Canon found the following issue with Canon EOS R10 cameras:

A small part of this product makes a loud noise […] when the built-in strobe fires.

Is your Canon EOS R10 part of this batch? Find out this way:

[EOS R10 cameras] with the serial number (on the bottom of the camera) of which the two digits from the left are “01” to “10”.

(For products sold in Japan, some products from “01” to “03” are eligible.)
See here to learn more…

CANON EF 50mm f/1.2L

Some units of the Canon EF 50mm f/1.2L lens might have this issue:

When shooting in a high temperature environment, the exposure may not be as intended, resulting in variations in the brightness of the images shot in the same scene, or an error “Err01” may occur.

How to find out if your lens is affected? Check the serial number. Canon states:

Some of the EF50mm F1.2L USM interchangeable lenses for single-lens reflex and mirrorless cameras produced in 2022.

Lenses with the 10-digit serial number printed on the lens body (see the figure on the right) whose four digits from the left are “1840”, “1940”, “2040”, “2140”, and “2240” are eligible.
See here to learn more…