How to choose the right lens for your camera

Last updated on July 25th, 2023 at 03:53 pm

Choosing the optics to combine with your camera is a fundamental step to enrich your kit. Let’s see how to deal with it.

How to choose a correct lens for any camera

If you have just purchased a reflex or mirrorless camera, I imagine the idea of buying a new lens can also wander around your head. It is definitely the right thought to do because if you purchased the camera only with the standard lens of the kit, know that it will never show you its full potential. Yes, because the optics of the kits that are on the market are not exactly the best you can have, consider it rather a limit. In this guide, I explain how to choose a lens, what are the factors to consider and where to start building your photographic equipment. 

The standard lenses that are sold in kits with cameras, usually with medium-low range ones, are zooms with little focal range, often even lower than that of many compact cameras. The most common lenses of the kits are in fact 18-55mm or 14-42mm, depending on the manufacturer and type of camera. To be clear we are talking about 3x zoom and there are compact cameras that easily reach 20x. Furthermore, even from a constructive point of view, it is not that they are the best. 

But do not immediately think that there is a second important expense ahead of you and that your optic kit should never be used, because in any case great progress has been made in recent years.

And if you have not yet purchased your camera but you are thinking about it, you could read my guide to buying a camera.

There are some important considerations to make before purchasing a lens, which I want to share with you to help you choose consciously.

When you buy a camera with interchangeable lenses, whether reflex or mirrorless, you automatically make a choice and accept the consequences that derive from it. The first is having to choose lenses from the same brand or those made by third parties for that particular manufacturer. Quite simply a Canon lens doesn’t have the same mount for Nikon’s bayonet, so it will only go on Canon cameras. But, even within the same brand, there may be differences, such as between mirrorless and reflex systems, but not only.

There are exceptions though: Panasonic and Olympus share the same mount for Micro Four Thirds cameras and Panasonic, this time together with Sigma and Leica share the L-Mount mount developed by the German company. Basically what I am trying to tell you is that the first thing to check to make sure that your camera has the appropriate mount for the lens you are going to buy.

How to choose a lens: the focal length

Have you ever wondered what exactly those measures that characterize all objectives represent? What exactly does 18-55mm mean? These figures represent the focal length of the lens. Focal length refers to the distance between the optical centre of the lens and the focusing plane (which is the sensor in digital cameras) and is expressed in millimetres. This length also determines to belong to one of the macro-categories in which we can divide the objectives: fisheye, wide-angle, normal, telephoto and macro.

The fisheye lenses, translated to the letter “fish eye”, are those that offer a wide angle of extreme vision and that is why they are also called the ultra-wide angle. This category includes lenses with a focal length of less than 14mm.

The wide-angle lenses, between 14mm and 35mm, are mainly used for landscape and architectural photography because of the wide-angle of view offered, ideal in these areas.

Normal or standard lenses are so defined because they are those that have a viewing angle almost equivalent to that of the human eye. They have focal lengths around 50mm and basically reproduce things as we see them with our eyes.

The telephoto lenses, on the other hand, have a focal length greater than 70mm and have as main feature that of enlarging the photographed subjects, narrowing the angle of view. They are used in portrait photography, in sports and nature photography. But not only of course.

Finally, there are macro lenses that allow you to get very close to the subject to photograph the smallest details. They do not have a well-defined range of focal lengths, but a feature to be taken into consideration when choosing macro lenses is also the minimum focusing distance. It is a fundamental value, which indicates the effective minimum distance to which you can approach the subject managing to focus. 

How to choose the right camera

At the end of this speech, you must also know there is an important aspect to consider in evaluating the focal lengths: I am talking about the magnification factor of the sensor. If you have a full-frame camera this is not for you, but if you have an APS-C or Micro Four Thirds sensor instead then you must consider doing some multiplication. Almost all APS-C cameras have a 1.5x multiplication factor (Canon wanted to distinguish and has a 1.6x factor), while for Micro Four Thirds the factor is 2x. What does it mean? It is soon said. On a camera whose sensor has a 1.5x magnification factor, a classic 50mm has an angle of view equivalent to that of a 75mm (50 × 1.5 = 75). In the same way, it is easy to multiply by 2, therefore on Micro Quattro Terzi, a 50mm will be equivalent to a 100mm. So when choosing a target, keep this variable in mind.

Fixed zoom and focal length

All the categories I have told you about so far can then be divided into two further families, that of zooms and that of fixed focal lenses. The former offers a variable focal length, while the latter, as the name implies, offer a single focal length.

In general, zoom lenses are clearly more practical since they can cover different situations with a single lens. Take the case of one of the most classic lenses, the 24-70mm: it is both a wide-angle and a standard one. But there is even more, there are handyman zooms, those like the 18-200mm or 28-300mm.

A common mistake is to consider zoom lenses all of the telephoto lenses, I often hear the two words used as if they were synonyms. I’m not at all! There are many zoom lenses that are born wide-angle and remain wide angle. An example would be the Sigma 12-24mm which has been hugely successful.

There is a reason, however, if professional photographers don’t use handyman lenses as their only perspective. Having to cover such a focal range, the image quality they can guarantee is not the same as zoom lenses with a smaller extension or fixed ones. They are less crisp and cannot offer the same brightness. This is due to the fact that the optical design would require very large lenses inside them to allow light to reach the sensor without excessive dispersion. The costs of elements of this type would be too high and this is why less valuable materials are used that allow keeping the price affordable.

The most common zooms for a photographer are the aforementioned 24-70mm, which is a good level kit is accompanied by a wide-angle zoom like a 16-35mm or something even more powerful like the 14-24mm. These lenses are usually associated with a telephoto lens such as the 70-200mm and in this way a photographer can try his hand in practically every photographic genre, relying on quality lenses. But building such a kit costs a lot of money, so before you get there I suggest you take another path, especially if you are a beginner.

In general, in fact, we have an incredible variety when it comes to zoom lenses: just take a look at the manufacturers’ sites to realize it. So to help you in choosing an initial zoom, the suggestion is to take a lens like a 55-200mm or a 70-300mm. The choice may depend on the type of camera on which the zoom will be mounted. A perspective of this kind, first of all, will not be too expensive (we can find it even for less than 200 euros) and will allow you to cover more or less all the focal lengths necessary for the first approach to photography. With the standard lens, you will have from wide-angle to normal and with the zoom from normal to telephoto.

This way you can try to find your way by having the tools you need to get started.

Don’t worry about buying third-party lenses, there are excellent manufacturers like Sigma and others like Tokina or Samyang that can offer really competitive prices.

The objective fixed focal instead, they do not have any focal range, this means that the zoom can only be achieved with your feet, physically approaching or moving you away from the subject. However, fixed lenses are those which in principle are able to offer the best image quality. Using a 50mm lens will surely guarantee sharper results than using a 50mm zoom. The optical structure is less complex than that of zoom and this allows the use of fewer lenses and therefore a better transmission of light. And if on the one hand, we have some that can cost an eye of the head, on the other, there are also at very low prices. As usual, the difference lies in the quality of the materials used for the realization: the more precious the glass used,

Among the fixed lenses we can also find many special lenses, such as macro or fisheye or as very high telephoto lenses such as 400mm, 600mm and even 800mm. 

Another feature that is common to almost all fixed lenses is the large aperture (indicated with the letter f) which allows a greater flow of light towards the sensor. More light that enters turns into a reduced depth of field and therefore a greater detachment of the floors.

Furthermore, the fixed ones are often an advantage also in terms of size, they can be very small and in particular, on mirrorless cameras, we can find them so thin as to be called “pancakes”.

The first steps in the world of fixed focal length lenses can be made by spending a little and bringing home lenses such as a 35mm f / 1.8 or a 50mm f / 1.8 that could cost you even less than 200 euros each. It depends from manufacturer to manufacturer and also from the sensor format of your camera.

How to choose a lens: the diaphragm

Once you have identified the focal length of the lens to be purchased, you will come across situations that are difficult to understand instantly. For example, you may have opted for a 50mm lens and find yourself facing two totally different prices despite the fact that the brand is the same: 150 euros (approximately) and over 1000. What does it depend on? One of the factors that most affect the price of a lens is the aperture or focal aperture. It is measured in f-stop and the lower the number the more the light that a lens is able to capture.

We remain on the example of the 50mm, to give exact figures we take into consideration the alternatives that Canon presents in the price list. There is a version sold for around 130 euros, one for 325 euros and the last one for 1130 euros. Next to each 50mm wording, you will also see the value of the maximum aperture that offers and despite very little changes the differences are great. The cheaper version has an aperture of f / 1.8, the middle version f / 1.4 and the more expensive one has a maximum aperture of f / 1.2. I must point out that the more expensive version also differs in the type of glass used for the lenses and body materials: these aspects also have their weight on the final price. The f / 1.2 version of the 50mm is part of the L range, which identify Canon’s professional lenses and you don’t need to aim so high to get started. But if you don’t think of using flash and above all of the shooting often in low light conditions it will be essential to opt for a lens with a maximum aperture of f / 2 or less . This aspect will allow you to shoot with even in critical conditions.

Most economic optics, except the fixed ones I just told you about, have a variable diaphragm. This means that based on the focal length at which we shoot we will have a different maximum available aperture. For example, in the case of the classic 18-55mm kit lens, the aperture is usually f / 3.5-5.6. It means that at the minimum focal range (18mm) you can count on a maximum aperture of f / 3.5, while at the maximum range (55mm) only off  f / 5.6. In practice, this means that photographing at 55mm this lens loses 1 and a half f-stops and therefore the light that can filter through the optical scheme will be less than half of what happens at 18mm.

Professional zooms, like the 24-70mm that I have already mentioned above, instead have a fixed aperture of f / 2.8. Thanks to the optical construction, therefore, they are able to maintain the same maximum aperture throughout the focal range. It is no coincidence that these targets cost around 2000 euros.

To give you some more examples, almost only for information, there are also objectives that see more than the human eye in practice and have smaller apertures at f / 1. In particular, I mention two, the Leica Noctilux 50mm f / 0.95 and the almost homonymous Nikkor Noct 58mm f / 0.95 for Nikon’s Z series mirrorless cameras. The price of such lenses is really high, the Leica one exceeds 10,000 euros, while the Nikkor branded one is on sale for “only” 8990 euros!

Optical image stabilization

If on the one hand many mirrorless cameras today offer integrated optical stabilization on the sensor to reduce blur is not the same for SLR cameras. It is for this reason that many optics can count on an optical stabilization system, which serves to prevent involuntary movements at the time of shooting to make images sharper. Each manufacturer has its own wording for these systems: for Canon, there is IS (Image Stabilization), for Nikon the VR (Vibration Reduction), Sony has its OSS (Optical Steady Shot) and so on.

Image stabilization is a function that is not necessary for every photographic genre and for every situation, but, especially in low light conditions when shutter speeds are longer, it allows us to bring home the results. It is also very useful when photographing with long focal lenses, while we can do without with fixed lenses with a large aperture. In fact, it is not common to find a stabilization system on fixed objectives.

How to choose a lens: autofocus

Last but not least there is one last, but very important topic to be addressed before choosing a goal. I’m talking about autofocus. There are some photographic genres for which today it is essential to have good autofocus, such as street photography, sports photography or nature photography. In all three cases, these are situations in which it is essential to capture the moment and therefore speed, but also silence, are fundamental. There are various types of focusing systems, more or less performing and also, in this case, the choice can be mainly determined by the budget. Keep in mind also that some manufacturers still have many options in the list with only manual focus and that with lenses equipped with AF we can always choose to use manual focus too. In some cases even when automatic mode is activated, perhaps to intervene and choose the focus point more precisely.

How to choose a goal: conclusions

Choosing the right lens mostly depends on what you want to photograph. As already mentioned, the first step in building a photographic kit is to choose which allow us to cover all focal lengths between 18 or at least 24mm and 200mm. You can do it by investing everything on a single handyman lens that allows you to travel light and never having to change your lens when you are out and about, or by selecting lenses other than the smaller focal range and which will surely offer greater image quality. The choice may clearly also depend on the budget available. Personally, I took the first steps in the world of photography with a 50mm f / 1.8, a 24-70mm and a 70-300mm.

The first because it represents a big step forward compared to the 18-55mm that I had in the kit on my reflex and it allowed me to start playing with the depth of field and the blurred thanks to the wide aperture. The 24-70mm because apparently every photographer must have one in their backpack, but above all because it is a zoom with which to deal with most photographic genres.

The 70-300mm zoom was a forced choice because professional optics, such as the 70-200mm have significant costs that are not worth tackling unless it is strictly necessary. With the 70-300mm zoom, you just have to be careful not to use it in low light conditions or maybe to photograph sports that take place in indoor buildings. But it certainly represents one of those optics that is better to have in your bag.

And to start expanding your kit, also remember that it may be wise to think of targets made by manufacturers such as Sigma, Tokina or Tamron to save some money to invest perhaps in other useful equipment. These manufacturers, however, guarantee excellent optics so do not be put off by the fact that they do not have the same brand as your camera.

I almost forgot, don’t call lenses the lenses, the lenses are the ones inside the lenses!