What does focal ratio mean, what does focal mean Meaning of focal point

The focal ratio is the ratio of the focal length of the telescope to the aperture, f = f d.

This ratio is the aperture on the camera lens. If the focal length is not convenient, the larger the aperture of the telescope, the smaller the focal ratio, and the brighter the image.

The focal ratio size has a very big impact on astrophotography, because if the focal ratio is twice that of someone else, it means your ** time.

Four times as many as others.

Optical zoom. The English name of optical zoom is opticalzoom, digital camera.

Relies on an optical lens structure to achieve zoom. The optical zoom of a digital camera is similar to that of a traditional 35mm camera, and the lens movement is used to zoom in and out of the object to be captured.

The larger the optical zoom factor, the farther away the subject can be captured, and the long-range shooting with the focal length adjusted is relatively clear for cameras that do not have strong zoom performance.

The basic meaning of the focal ratio is:

In the field of ironmaking, the coke ratio is one of the technical and economic indicators of blast furnace ironmaking, that is, the tonnage of coke consumed by the blast furnace for every ton of qualified pig iron smelted.

In optics, the focal ratio in an optical system expresses the ratio of the focal length of a telescope to its aperture.

The zoom ratio refers to the multiple of the focal length of the camera lens from the short focus end to the long photo end - for example: 28mm 112mm is 4x zoom (that is, 28*4=112), and the zoom ratio of the lens is calculated from this!

In fact, it is the size ratio of the picture, and the same distance can be projected into different sizes of pictures.

What are you referring to?

The coke ratio is one of the technical and economic indicators of blast furnace ironmaking. That is, the tonnage of coke consumed by the blast furnace for every ton of qualified pig iron smelted. In optics, the focal ratio in an optical system expresses the relationship between the focal length of the lens and the size of the aperture diameter.

Coke ratio = coke consumption per day and night (tons) Pig iron production per day and night (tons) or the amount of coke consumed per ton of pig iron smelted on average, expressed in kilograms.

Explanation of the joule ratio.

The ratio of the amount of coke consumed to the amount of pig iron smelted during iron smelting. Generally, it is expressed as the average amount of dry coke (tons) consumed per ton of qualified pig iron.

Word decomposition Explanation of coke Burnt ā The object is burned into black and yellow and is hard and brittle: burnt. Ravages of war.

Burnt out. Irritability, anxious: anxious.

Anxiety. Anxious. Restlessness .

Crispy, crispy: charred crispy. Burnt dates.

Yu is extremely dry: the lips are burnt and the mouth is dry. Scorched.

Scorched. Parched. An explanation of a hard, porous, and high calorific ratio ratio ǐ contest high and low, length, distance and proximity, good or bad, etc

Race. Than. Contrast.

Rating. Matchable: Not what it used to be.

Unbeatable. Indicates that the comparison between the wins and losses of the two sides in the game is three to two.

Represents the relationship between two numbers such as multiples, fractions, etc.: proportion. Ratio.

Metaphor, imitation: for example. Compare.

1. Original meaning: The object becomes black and yellow after being burned and becomes hard and brittle. Such as: scorched, scorched earth, scorched head.

2. Derivation: By extension, it means "irritability, anxiety". Such as: anxious, anxious, anxious, restless.

3. Derivation: By extension, it refers to "the metaphor is dry to the extreme". Such as: lips are scorched, dry, scorched, and thirsty.

4. Derivation: also used as a surname.

The meaning of coke is: too much heat or too much fire, making things hard and brittle or burning into charcoal; Disturbance due to lack of moisture, become dry and dry; Worry; Refers to coke; Abbreviation for Joule.

The pinyin of Jiao is: jiāo, the radical of Jiao is 隹, the stroke is 12, the stroke order is apostrophe, vertical, point, horizontal, horizontal, horizontal, vertical, horizontal, point, five elements of fire, five strokes is wyou. It is scorched, and it is injured by fire.

Say slow grasp of the text". The grains are scorched. - Mozi Fei Conquered.

If it is young, it is scorched but not cooked. ——Lü's Spring and Autumn Period: Ying Yan".

Compound words of Jiao. 1. Anxious: (shaped) very anxious.

2. Burned: The appearance of the head being burned by fire is a metaphor for the situation or situation is very embarrassing.

3. Coking: refers to the process of introducing air into the catalyst bed and burning the carbon deposits on the catalyst by combustion, so as to restore the activity of the catalyst.

4. Focus: (name) The key point of the metaphorical problem or the focus of the argument.

5. Restlessness: Anxious and irritable, uncertain. From Shen Shixi's "The Last War Elephant".

6. Thirst: very thirsty.

7. Focus: Refers to the concentration of a beam of light at one point, which is a metaphor for the concentration of sight and attention at one point.

8. Anxiety: (formal) anxious and worried.

9. Focal length: the distance from the apex of the parabolic mirror or the center of the thin lens to the main focus.

10. Coke: bituminous coal is a kind of iron-making fuel prepared under high temperature and closed conditions.

Example sentences containing coke

1. Anxiously waiting for someone to come, anxious, like an ant on a hot pot, sitting or standing, constantly repeating the action of doing and standing, his eyes are fixed in the direction of the door, and the whole person looks extremely anxious.

2. There is a faint smell of burnt smell in the field, the sun bakes everything that is ripe into a skin and is quietly ripe, and the yellow maple leaves are mixed with ochre oak leaves, all the way to the sky.

Focal length is originally a quantity in optics, when a beam of parallel light passes through the Convex Lens with the principal axis of the convex lens, the other side of the convex lens will be converged by the convex lens into a quiet mode point, which is called the focal point, and the distance from the focal point to the optical center of the convex lens is called the focal length of the convex lens. A convex lens has a focal point on each side.

Optical center: The center of the convex lens can be approximated as the optical center.

The lens of the camera we use is equivalent to a convex lens, and the film (or the sensor of the digital camera) is located near the focal point of the convex lens, or in other words, the distance between the film and the center of the convex lens is about equal to the focal length of the convex lens.

The convex lens can be imaged, and when the convex pin lens is used as the lens of the camera, the clearest image it becomes generally does not fall exactly on the focal point, or in other words, the distance from the clearest image to the center of light (image distance) is generally not equal to the focal length, but slightly larger than the focal length. The specific distance is related to the distance between the illuminated object and the lens (object distance), the larger the object distance, the smaller the image distance, (but in fact it is always greater than the focal length).

Because when we take pictures, the distance between the object being photographed and the camera (lens) is not always the same, for example, when we take a picture of someone, sometimes, if we want to take a picture of the whole body, we are far away, and if we take a picture of half of the body, we are close. In other words, the image distance is not always fixed, so in order to get a clear image, it is necessary to change the distance from the film to the center of the lens according to the distance of the object, and this change process is what we usually call "focusing".

From the above description, the focal length of a convex lens is a fixed number. In other words, the focal length of a convex lens cannot be adjusted. The focal length of the lens of a considerable number of cameras cannot be adjusted, which is called a "fixed focus (distance) lens", so the "focusing" mentioned above (we usually speak) is not really adjusting the focal length of the lens!

There is only another part of the camera, and its lens is a "zoom lens", that is, those lenses that can be "zoomed", and with such a camera is the real "adjustment of the focal length" when doing the zoom!

The "zoom lens" is more complex than the "prime lens", so it will generally be higher.

1.The object turns black and yellow and becomes hard and brittle after being burned. Earth. Head rotten.

2.Irritable, anxious: Anxious. Consider. Burn. Resistant to wide restlessness.

3.Crispy, crispy: Crispy. Chang sells bright dates.

4.Dry to the extreme: lips and mouth. Withered. Crack. Thirsty.

5.A hard, porous, high-calorific solid fuel: charcoal. Coal. Refine.

6.Surname.

The zoom ratio refers to the multiple between the focal length of the camera lens from the short focus end to the round telephoto end - for example, 28mm 112mm is 4x zoom (that is, 28*4=112), so as to calculate, the zoom ratio of the lens is collapsed!

The basic meaning of the focal ratio is:

In the field of ironmaking, the coke ratio is one of the technical and economic indicators of blast furnace ironmaking, that is, the tonnage of coke consumed by the blast furnace for every ton of qualified pig iron smelted.

The focal ratio in an optical system expresses the ratio of the focal length to the aperture of the telescope.

The biggest advantage of this type of lens is that it is small and easy to carry. People say that they are special lenses for tourism or "one shot to go all over the world", it is precisely because of their lightweight characteristics, but also because of their wide focal length coverage, so in fact, it is suitable for all kinds of shooting needs. In contrast, beginners in photography are more suitable for this type of lens.

On the one hand, because it is lightweight, and on the other hand, because it can effectively save the initial investment, and at the same time can meet a variety of shooting needs. Frequent travelers should also be equipped with one of these lenses, after all, it is important to reduce the weight of the load during long journeys.