In both photography and video, lenses (also called lenses) are a set of converging and diverging lenses that allow light beams to be redirected to create an optical image in a photosensitive format. The lenses are placed on the front of the camera just in front of the sensor.
Absolutely all cameras need a lens, although it depends on the camera, this lens can be interchangeable and very bulky, as in the case of reflex cameras, or fixed and very small, as is the case of mobile phones.
In the market there are all kinds of lenses, some have zoom, others are fixed focal, there are able to capture 180 degrees, others only capture the image at a small point, etc. Next we will see the different types of lenses and their characteristics.
The focal length
The focal length of a lens is the range that this lens will have, that is, the greater the focal distance, the more zoomed and we can photograph objects or things that are farther away. Depending on the focal length, the lenses are used for different types of photography.
These lenses have an angle of vision that is around 180º. Its focal length is usually between 6 and 16mm. The main characteristic of these lenses is that they distort the lines a lot, as you can see in the following image. They are usually used mainly in landscapes and especially in cities.
The angle of vision of this type of lens goes from 63º to 180º and the focal distance is between 18 and 35mm. These types of lenses are mainly used for landscapes, although they can also be used for cities or towns. The following photograph is made with a 24mm lens.
The angle of vision of this type of lens is 45º and the focal length is between 35 and 50mm. The proportion they are able to show is similar to that of the human eye. These goals are often the favorites of many photographers because they are the ones that cover the greatest amount of possibilities, there are those who use them for landscapes, others for urban exploration, portraits or for still lifes to give a few examples. The good thing about these lenses is that they do not produce any distortion in the lines, something that does happen both in those that we have already seen and those that are still to be seen. The next picture was taken with a 50mm lens.
The angle of vision is 30º downwards and the focal lengths range from 70mm onwards and can reach 600mm and even much more. They are widely used by journalists, especially sports and also by animal photographers, because it allows you to photograph animals in the foreground that are quite far away. Imagine that you want to photograph a bear, I do not think it’s funny to approach you less than 100 meters to give an example. This type of lenses generate the bokeh effect, which I will talk about in another article but for you to get an idea are those photographs where the background is blurred and out of focus and only the main character comes out completely clear. The following photograph is made with a distance of 105mm.
The luminosity of the lenses
Apart from the focal distance another of the most important characteristics of the lenses is its luminosity.
When we are going to buy a lens other than the focal distance, another number appears accompanying an f, such as ¨f / 2.8¨ or ¨f / 1.4¨. Well, this tells us what is the maximum aperture of the diaphragm that can reach the target for a certain focal distance. The smaller the number the brighter the target is.
We must bear in mind that the greater the focal distance, the lower the brightness of the lens. For example, if we buy a lens with a fixed focal length of 24mm and an f / 4 we can say that it is not too bright, however for a 300mm it would be just the opposite. The reason is that the greater the focal distance the more difficult it is to make a luminous lens.
On the other hand, the lenses with fixed focal points are normally brighter than those with zoom. The latter must be taken into account when buying them that come with two values f. For example, an 18-50 f / 3.5 – f / 5, means that at 18 the opening will be 3.5 and at 50 it will be 5. The reason is the one that we explained before, at a greater focal distance less luminosity, and when varying it in the zoom the aperture limits of the diaphragm also vary.
Advantages of luminous lenses
The lenses with a maximum opening from f / 2.8 usually generate a much better bokeh effect than in more closed apertures. You can see it in the photograph of the daisy.
In low light conditions we can shoot at lower speeds, which is very beneficial if we shoot without a tripod, since the image at high speeds can get out of shape, as if we shoot with it, because when increasing speed or ISO we run the risk of that grain appears in our photographs.
The lenses lose some sharpness when used at maximum and minimum opening. The good thing about a luminous lens, for example a ¨f / 1.8¨ is that if we shoot at ¨f / 5.6 “we will obtain a higher image quality than if we use a ¨f / 4.5¨. The reason is because in this second the opening is very close to its limit.
Disadvantages of luminous lenses
The problem with this type of lens is its price, which shoots up. Before buying one of these lenses we must be clear so that we will use it and if we really need it.
The focus distance is the minimum distance at which the subject must be in order for the lens to focus on it.
This point must be taken into account for macro photography. If we want to photograph flowers or very small bugs we must have a lens with a rather high focal length and a small focusing distance. To give an example, to photograph flowers a good combination would be a 105mm and a focus distance of approximately 25cm. The following picture is made with that focal and focus distance.
The focusing motor
Most of the lenses are incorporated with a focus motor, although there are still some that do not, so it is important to note if our camera has its own focusing motor, otherwise we can only focus in manual mode.
When buying a goal you have to take into account the speed and accuracy with which it focuses. For example, if we want to do sports photography or birds the focus motor should be as fast as possible, otherwise it may be that when we make the photo our protagonist has already ¨volado¨. If we are going to take pictures of landscapes, this point will not be so important.
I do not need to tell you that the more precise and fast a target is when focusing the more expensive it comes out.
The image stabilizer is a small help that can take some lenses or cameras so that the photographs do not move. It is important to know that the image stabilizer always subtracts a quality pelin from the final image, so if your lens has a stabilizer, you have to have it disconnected except for those occasions when it is necessary.
Fixed and zoom lens
The difference between a fixed and a zoom lens is that the second has different focal lengths and the first one does not. Haber if I explain myself better. A fixed lens only has a focal length, for example 50mm and we can only shoot at that distance, on the other hand the zoom has several “positions” for example with an 18-50, we can shoot at any focal distance between these two numbers.
And now you are thinking, and for what are fixed lenses? Everything has a reason, and that is that the fixed lenseshave a number of advantages over zoom that some photographers take very much into account. Let’s see them.
Advantages of a fixed lens
Better image quality Go, we already have a very important advantage, and because, because these lenses need less crystals inside, which improves the sharpness, but beware, that does not mean that all the fixed ones are better than the zoom, there are always exceptions
More bright. And the reason is also because they have less crystals and allow more light to pass to the sensor. That a goal is luminous is very important as we have seen before.
They are cheaper: For the quality of image that they take out they are usually cheap, but beware, it also has a disadvantage that we will see later.
They are smaller: As a general rule they are smaller and weigh less, although there are exceptions.
Disadvantages of a fixed lens
You need to buy more lenses: Before we said that they are cheaper, and it is true, but if you need a 24mm and a 50mm the sum of the two prices may exceed a 24-50 zoom.
You will carry more goals in the backpack: If you are one of those who go out to make your photos in the countryside or in the city, it is normal for you to take more than one lens behind, something that is not necessary with the zoom.
Stains on the sensor: If you use fixed focal points you will have to change the lens of your camera many times, this can cause dust to get in and the sensor to get dirty. Cleaning it is possible but, but it is a disadvantage more.
You will have to move: If you use a fixed one and you do not like a frame you should move, if you were to zoom, you should simply adjust the focal length.
I’ll leave it in a draw, four advantages and four disadvantages for not giving more advantages to one or the other.
The last thing you have to take into account is that depending on the brand of our camera we will have to have one mount or another. When we buy a goal is something that we must take into account, but quiet, when you buy it as normal is that in the name of the product put something like “for nikon saddles” or “for canon mounts”. Obviously this does not happen when Nikon or Canon among other brands that make the goal, but there are other brands such as Sigma or Tamron where we should look at this detail.
Regarding which brands are better there is no clear answer, each photographer will tell you something different, but there is something I can tell you, cheaper brands such as Sigma or Tamron have very good quality lenses, such as the Sigma 50mm of his Art collection