What are the rules for using zoom lenses?
Zoom lenses can change the focal length without changing lenses. A zoom lens has a variable focal length. For example, with an 80-200mm zoom lens, you can usually get any focal length between 80-200mm by simply turning the lens barrel. Today’s optical industry uses computers to design lenses and has produced many excellent zoom lenses. So how to use the zoom lens well? Follow these 10 rules to get the most out of your zoom lens.
1. Ten principles to follow for a good zoom lens
(1) Use long focal length to focus
When using zoom lenses, the correct focusing method is to focus on long focal length first, and then choose the appropriate focal length for shooting; At long focal lengths, the image of the subject is the largest and the depth of field is the smallest, making it easy to focus accurately.
In the case of backlighting or complex lighting situations, it is also helpful to select appropriate local metering without approaching the subject for metering. In the usual shooting, often with a medium or long focal length zoom lens, with the longest focal length focus and metering, lock exposure and then choose the ideal focal length shooting, so that there is no need to move back and forth footsteps.

(2) More attempts should be made on each focal length
Although most photography enthusiasts are extremely concerned about the zoom ratio of the zoom lens, the specific use of long focal length is often used most, some even treat it as a fixed focus telephoto lens. In fact, when you try to use different focal lengths to get a completely different picture, you will find that the zoom lens as a variable viewfinder has considerable potential.
(3) Familiar with zoom lens operation
On early zoom lenses, zoom and focus were adjusted separately by two rings. Most zoom lenses are now controlled by a single ring, which is characterized by pushing and pulling the lens back and forth to change the focal length and rotating it left and right to focus.
Therefore, for photography enthusiasts who have just bought a new mirror, they should be familiar with and keep in mind the direction of the zoom and the left and right positions of the focus, so as to avoid affecting the clarity of the zoom by slightly rotating the adjustment ring after accurate focus. This is why many “conservative” photographers prefer to use the old dual-ring zoom lens.
(4) Appropriate use of support
When using a zoom lens with a focal length of 200mm or longer, the lens should be fixed on a tripod and other supports to ensure the stability of shooting.

(5) Choose a suitable hood
Zoom lenses are more prone to flare than other types of lenses, so a proper hood is essential. Sometimes the shade created by the hood is not visible on the frame screen of a single-lens reflex camera, but it shows up on film. This is most obvious when shooting with a small aperture, often causing the hood to fall into the depth of the field.
In addition, some shades are effective at the long focal length end, but when zooming to the short focal length end is used, the picture will have a halo effect caused by occlusion that is not visible on the framing screen. Therefore, it is very important to choose an appropriate hood for the zoom lens and use it reasonably.
(6) Add the distance increasing lens
Below the circumstances that need to use extremely long focal length, spend very little money to buy a lens of 2 multiplication distance, can change your 70-210mm lens into 140-420mm super long zoom lens immediately at will, the lens of 3 multiplication distance can achieve 210- 630mm more, make your lenses into the ranks of astronomical telescopes immediately. However, the cost will be the loss of aperture levels and the clarity of the photos taken.
For example, an F4 zoom lens with a multiplier of 2 will lose two steps of aperture to F8. The maximum aperture becomes F11 with the addition of 3 multiplier lenses. As you know, the best way to get the most out of a lens is to shoot at an aperture two notches below the maximum aperture. Therefore, high-speed film and a tripod must be considered when adding an extender lens, and the subject should be still.

(7) Be careful with the filter
Under normal circumstances, they do not easily zoom lenses with filter lens. In a beach or saltwater environment, you really need a protective mirror. Polarizers are used to change color temperatures and create special effects, such as darkening the sky and eliminating reflections. On top of that, adding some optional filters will only add to the already frustrating problem of light reflection from inside the lens.
(8) Control the depth of the picture
A 60mm focal length shot with a zoom lens 1.5 meters from the subject is the same size as a 300mm focal length shot at 7.5 meters from the subject. The difference is the depth of the image. Photos taken with a 60mm focal length have a sense of depth and space in the background. And 300mm focal length shooting, giving the impression that the scenery is compressed, the subject and the scenery seem to be “close”.
(9) Keep a distance to prevent deformation
When shooting at the wide-angle end of the zoom lens, it is important to keep a proper distance from the subject to avoid distortion. Keep in mind that distance, not focal length, is the main factor that affects perspective.

(10) Tricks to control depth of field
An experiment can be done by taking two pictures at the same aperture and at the same distance at 25mm and 50mm focal lengths, and then enlarging the picture taken at 25mm focal length so that the subject image in the picture is the same size as the one in the 50mm one. When you compare the backgrounds of the two photos, you can see that the background in the enlarged photo is not as hazy as the first one, and you actually get a more useful depth of field. This method is also effective for wide-angle lenses with a fixed focus.
2. How to ensure the clarity of the whole focal segment of the zoom lens?
Short focal length lens, wide-angle perspective, commonly known as wide-angle lens or fisheye lens, the focal length is generally 16mm, suitable for shooting large landscape photos, large depth of field image clear. Standard lens center, the focal length is about 50mm, is one of the most commonly used lenses, telephoto lens, focal length in 100mm to 1000mm, commonly known as a telephoto lens, its narrow perspective of short depth of field can shoot distant objects, you can configure 25mm to 125mm zoom lens is the most practical, of course, You can also choose a zoom lens of 80 to 200mm according to your own needs.
This lens can highlight the theme of portraits or flowers, blur the background. The optical glass of the camera lens is very soft and easy to scratch. Be careful to protect it and avoid rubbing it as much as possible. When really rubbing it, professional lens paper or deerskin should be used to prevent the scratched lens from affecting the shooting effect in the future.

FAQ:
What is the most practical zoom lens segment?
For zoom lens focal length should be the most practical is the most SLR camera lenses used set of 18 to 55 mm and 18-105 – mm lens.
How to zoom a DSLR camera when shooting a video?
Optical zoom can be achieved by turning the zoom ring on the lens, which is not operated by the camera body.
Do prime or zoom lenses have better picture quality?
There is a saying in the camera circle: fixed focus has no weakness! This means that almost all prime lenses are fairly good (relative to zoom lenses at the same price). As the prime lens does not need to consider multiple optical requirements like the zoom head, it is much simpler than the zoom head in structure, so it is not difficult to understand that at the same price, the prime lens can use a better light transmission lens, and can use a larger aperture.