Cameras and lenses are the golden companions of photography. But we always talk about cameras more, but ignore the importance of lenses. Whether you are a novice or a veteran driver, you must have more than one lens on the road of photography. The original lens may have been forgotten long ago. So about the purchase of the lens, here are ten things I want to share with you.
1. What is the difference between a fixed focus lens and a zoom lens
lenses are divided into broad categories, mainly divided into two categories: fixed focus lens and zoom lens.
A fixed focal length lens, as the name implies, is a lens with a fixed focal length, such as Canon RF50mm F1.2 L USM. In other words, fixed-focus lenses cannot zoom, and zooming can only be done by moving the position of the photographer. Fixed focus lenses generally have the characteristics of a large aperture, such as F1.2 aperture, which has more advantages than zoom lenses. In theory, the picture quality of a fixed focus lens will be better than that of a zoom lens, but this sentence is also relatively speaking.
fixed focus lens Canon RF50mm F1.2 L USM
zoom lens, as the name implies, it can change the focal length, such as Canon RF24-70mm F2.8 L IS USM, the focal length can be changed from 24mm to 70mm. When using, the user can keep the position to take pictures of different focal lengths. The zoom lens is divided into constant aperture and variable aperture, which we will introduce to you separately later. The lens we give an example is a zoom lens with a constant aperture.
2, what is a wide-angle lens, standard lens, telephoto lens, etc.
If you carefully classify the lens, you can start from the focal length Proceed. Starting from the focal length classification, then the types of lenses are very rich, such as fisheye lenses, wide-angle lenses, standard lenses, telephoto lenses and super telephoto lenses. Of course, there are other categories such as shift lens, macro lens, because it is not a common lens, we will not discuss it.
fisheye lens, generally the focal length is less than 16mm can be called fisheye lens, such as Canon EF 8-15mm f/4L USM.
Wide-angle lens, generally a lens with a focal length greater than 16mm and less than 35mm can be called a wide-angle lens, such as Canon RF15-35mm F2.8 L IS USM.
Canon RF15-35mm F2.8 L IS USM
standard lens, generally the focal length is greater than 35mm, less than 70mm, can be called Standard lens, but in many cases it will have a wider range. For example, Canon RF24-70mm F2.8 L IS USM is a standard zoom lens.
Canon RF70-200mm F2.8 L IS USM
telephoto lens, generally the focal length is greater than 70mm, less than 200mm lens, can be called It is a telephoto lens, such as Canon RF70-200mm F2.8 L IS USM.
Super telephoto lens, generally the focal length is greater than 200mm can be called super telephoto lens, such as Canon EF 100-400mm f/4.5-5.6L IS II USM and Canon EF 800mm f/5.6L IS USM.
3. What is the “big three yuan”
If divided by focal length, there are two special The combination is called a “big three yuan” lens and the other a “small three yuan” lens.
”big three yuan” refers to the combination of wide-angle, standard and telephoto zoom lenses with a constant aperture of F2.8, such as Canon RF15-35mm F2.8 L IS USM, Canon RF24- The combination of the three lenses of 70mm F2.8 L IS USM and Canon RF70-200mm F2.8 L IS USM is the “big three yuan”.
Canon RF15-35mm F2.8 L IS USM and Canon RF70-200mm F2.8 L IS USM
Focal length: 190mm Aperture: f/4 ISO sensitivity: 800
Exposure time: 1/320 Exposure compensation: 0EV White balance: Auto
Here is one more thing. Generally, the “big three yuan” lens is a very good zoom lens, so the performance in terms of image quality is very good, even better than some fixed focus lenses. For example, the three lenses of the Canon RF series have outstanding overall image quality performance. This is also the outstanding achievement of Canon’s concentrated research on optics for many years.
4. What is “small three yuan”
“small three yuan” refers to a wide-angle, F4.0 constant aperture, The combination of standard and telephoto three zoom lenses, such as Canon EF16-35mm f4L IS USM, Canon EF 24-70mm f/4L IS USM and Canon EF 70-200mm f/4L IS II USM. This combination is a “small three yuan”.
Generally, after the photography has advanced to full-frame cameras, the first choice to buy is the “small three yuan” or “big three yuan” lens combination.
5. The aperture and the aperture blade of the lens
Then I will talk about the unfinished topic above, the aperture of the lens. The lens aperture value controls the blur effect of the picture and the amount of light. The larger the aperture, the smaller the value, such as F1.2, F2.0, the larger the amount of light entering, the more obvious the blur effect of the picture; the smaller the aperture, the larger the value, such as F8, F11, the smaller the amount of light entering, the virtual image The less obvious the chemical effect.
The aperture marked on the lens is the maximum aperture value that this lens can reach.
Constant aperture lens
General fixed-focus lenses have constant aperture value, and the aperture is generally larger, such as Canon RF50mm F1.2 L USM And Canon RF85mm F1.2 L USM, the aperture of the two lenses is F1.2.
variable aperture lens
If it is a zoom lens, the aperture is divided into two situations: constant aperture and variable aperture. For example, the Canon RF28-70mm F2 L USM is a lens with a constant F2 large aperture; another example is the Canon RF24-240mm F4-6.3 IS USM, the aperture can be changed from F4 to F6.3.
focal length: 50mm aperture: f/1.2 ISO sensitivity: 100
Exposure time: 1/2000 Exposure compensation: 1EV White balance: Auto
The numerical value of the aperture is changed, and the response on the lens is The opening size of the aperture blade. Generally, high-end lenses such as Canon’s RF series have a very rich number of aperture blades, so that the spot formed by the lens can be closer to a circle. In theory, the more iris blades, the better, to achieve a better light spot picture effect.
6. Lens bayonet
The lens bayonet system is a bridge between the camera and the lens. Especially in the past two years, as many manufacturers have joined the competition of full-frame mirrorless camera products, a brand-new bayonet system has also been ushered in. For example, Canon, from the EF mount of the SLR system, ushered in the RF mount of the full-frame mirrorless system.
From the EF mount of the SLR to the RF mount of the micro-single, in fact, Canon does not have the inner diameter of the mount Change, but the flange distance is shorter. The flange distance is the distance from the lens to the sensor. Since the Canon EF series lens itself has the tradition of F1.2 super large aperture, after coming to the RF series lens, it has also launched a number of high-end lenses with F1.2 super large aperture.
RF mount to EF mount lens adapter ring
officially benefits from the advantages of the short flange distance of the RF mount, so Canon’s full-frame mirrorless EOSR and EOSRP two cameras can be non-destructively connected to the EF mount system lens through the official adapter ring, so that the lens selection is more abundant.
In the camera and lens bayonet system, the larger the inner diameter of the bayonet, the larger the aperture lens can be manufactured; the shorter the flange distance, the more possibilities for transfer. This is the current advantage of Canon’s RF mount system.
7. Anti-shake technology of the lens
For the standard focal length or long focal length lens, it is easy to use daily The shooting is virtual, so the anti-shake technology of the lens is very important. Canon has long introduced image stabilizer technology on the lens, which effectively solves the problem of hand-held telephoto lenses that are prone to jitter when shooting. The image stabilizer developed independently by Canon compensates for shake by moving part of the optical system in parallel, thereby reducing shooting failures caused by shake.
”IS” anti-shake logo
Focal length: 70mm Aperture: f/2.8 ISO sensitivity: 6400
Exposure time: 1/10 Exposure compensation: 0EV White balance: Auto
All Canon lenses with IS logo are equipped with image stabilizers, such as RF series “big three yuan” lens Canon RF15-35mm F2.8 L IS USM, Canon RF24- 70mm F2.8 L IS USM and Canon RF70-200mm F2.8 L IS USM and “small three yuan” Canon EF16-35mm f4L IS USM, Canon EF 24-70mm f/4L IS USM and Canon EF 70-200mm f/4L IS II USM.
8, the focusing speed depends on the motor
The focusing motor has a very large impact on the lens focusing experience, so choose the lens At that time, be sure to choose products equipped with excellent focus motor technology.
Since the advent of autofocus technology, the focus motor of the lens has made considerable progress, and Canon’s USM ultrasonic motor is a word that must be mentioned. The full name of USM is Ultrasonic Motor, which means “ultrasonic motor”. Its principle is to achieve focus drive by using ultrasonic vibration as a rotating energy source. Compared with ordinary focus motors, it has high efficiency, high torque, high sensitivity, low energy consumption and low noise The advantage of this, while also achieving full-time manual focus.
USM motor includes ring USM, micro USM and NANO USM
In 1987, Canon first applied this technology to the lens, and it has been Very mature. Almost all Canon EF and RF series lenses are now equipped with this technology. In daily applications, USM allows users to experience a faster, more accurate and stable focusing experience, ensuring that users can experience the ideal focusing effect when taking all photos.
9. The impact of coating technology on the lens
When it comes to coating, it is necessary to mention two Canon coating technologies, SWC And ASC.
SWC coating forms a wedge-shaped microstructure on the surface of the lens that is smaller than the wavelength of visible light. This structure can continuously change the refractive index, thereby eliminating the boundary where the refractive index will suddenly change, and suppressing reflection through structural characteristics Therefore, it has excellent effects in ghost and flare suppression.
RF lens coating
ASC coating is called air spherical coating, and its structure can be regarded as a composite coating, which consists of two parts Composition, the lower layer is a vapor coating, and the thicker part is a low refractive index layer formed by uniformly injecting low refractive index bubbles into the coating. ASC coating is still to solve problems such as glare and ghosting.
Canon’s RF series lenses have widely used SWC and ASC coating technologies. The SWC coating is used in conjunction with the ASC coating, where SWC is used for large arc surfaces, and ASC is used for flat or small arc surfaces, which fully suppresses the glare and ghosting caused by light reflection.
In daily shooting, don’t underestimate this small coating. For backlighting environments, Canon’s SWC and ASC can help EF and RF series lenses achieve better picture performance.
10, custom function ring
When we used to take pictures, the adjustment parameters were mainly based on the camera. As the lens developed, more functions were added. In Canon’s RF series lenses, a user-friendly design of a custom function ring has been added. Now, this custom function ring design is the standard configuration of Canon RF series lenses, bringing more convenience for users to adjust operations during shooting.
RF lens custom function ring
When in use, the customization of the control ring can greatly improve the EOS R system. Level menu operation efficiency. Controlling body parameters through the lens further improves the interaction between the body and the lens. This is a revolutionary change in the lens.
In fact, when we buy lenses, in addition to the purchase budget and price, the selection of other parts is more important. After all, many people buy lenses that will accompany them for many years. The focal length of the lens, the size of the aperture, anti-shake technology, coating technology, and other functions should all be in the reference category. Just like Canon’s RF series lenses, on the basis of excellent optical quality, it also has a more user-friendly design. With the EOSR micro system, it can take photos to the next level.
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