Fixed focal length lenses between 35 and 50 mm: why you need one

We have already mentioned in a previous article 7 mistakes made when using a wide angle lens and today we explain why you should own one or more medium fixed focal length lenses (standard, between 35 and 50 mm) and always have them in your backpack for really successful photos.

When starting out in SLR photography, one usually buys a basic equipment composed of a medium-low range body and its corresponding access zoom lens (18-55 mm). That is to say the typical kit of initiation very often signed by the big brands that are Canon and Nikon.

These zoom lens kits fulfill an essential purpose, which justifies their purchase: their low price and their versatility make them excellent companions for all those who want to launch themselves into the magical world of photography.

Characteristics of the zoom lens kits

These lenses normally range from 18mm to 55mm and basically have apertures up to f/3.5 at best. With time, we observe that the results are not really up to the mark since their quality is generally quite limited.

First, the definition is poor and generally accompanied by a lack of sharpness, which is even more accentuated on the edges of the image. In fact, this sometimes results in images with little definition or even blurred. The distortions are striking, especially on wider angle positions. The chromatic aberrations sometimes generated color the "fine" elements of the edges of the image.

But the worst of all, at least from my point of view, is that everything gets worse as soon as you apply a little zoom: the aperture is reduced by one or two stops, for a maximum value at f/5.6. This gives tragic situations when you want to shoot in low light, for normal situations in many other cases.

All this leads us enthusiasts to consider the acquisition of a new lens, once we have acquired the equipment to access the photo. And this is the purpose of this article.

Therefore, the first thing we will see are the advantages and disadvantages of fixed lenses compared to zoom lenses. Further on, we will see the most attractive focal lengths and what is offered on the market.

Fixed lenses VS zoom lenses

The age-old question that every photographer asks: fixed or zoom lens? We will examine a set of elements to be taken into account:

Maximum aperture

The introductory zoom lenses have very low maximum apertures, so that if the light conditions get worse, you will have to play with the ISO, use a flash or pray that the image is not blurred at the time of release. On the other hand, on fixed focal length lenses, the maximum apertures are generally quite high (or bright). In most cases, they are less than f/2, which gives three or four extra stops of brightness. This will allow you to significantly reduce the ISO or lower the exposure times. Four stops would be like getting the same brightness at 1/20 as at 1/320 or at ISO 800 as at ISO 100, with all that implies.

At the same time, having a large maximum aperture will allow you to play with the depth of field of your images: you can reduce it well compared to the standard lens. You can play with selective focus and make one of the featured elements stand out in the image, compared to the other elements.

Conversely, the reduction in aperture is so applicable to either lens that you'll have no problem if you ever want to shoot with hyperfocal and take advantage of the greater depth of field.

Focusing on fixed focal length lenses

Still considering this factor, another interesting point, which cannot be ignored, is that fixed focal length lenses with larger apertures focus more quickly or faster than zoom lenses. And one might add that they are not only faster but also more accurate. This is because by opening the aperture wider, more light gets into the camera. Because of this, the sensors or focusing elements work better and faster because they have more information to work with.

Just look at the way an autofocus lens works: no matter how closed the aperture is when focusing, they let in as much light as possible for the sensors to work with, and just as they are about to take the picture, they close the aperture to take the picture. That's why the more advanced cameras have a button next to the lens, called the depth of field preview button, which, when pressed, closes the lens to the preset aperture. And there, the depth of field is observed with a generalized darkening, due to a much reduced passage of light (depending on the f value set).

Optical quality

Zoom lenses need more lenses than fixed focal length lenses, so at the same cost, the quality of these lenses is a bit lower. The fact that the light has to pass through a large number of lenses produces more filtering, more difficulty and loss of sharpness, as well as an increase in aberrations (and brightness too, discussed in the previous section).

Therefore, fixed focal length lenses give a higher image quality than zoom lenses, especially when comparing the same focal length. This increase in quality is valid on basic lenses, to increase considerably as we move to higher end lenses. This will clearly translate into a general improvement of the image, with sharper, less blurred photos, with greater definition and probably with less or no chromatic aberrations.

Weight and size of fixed focal length and zoom lenses

As we have seen before, fixed focal length lenses need fewer lenses than zoom lenses. This makes fixed focal length lenses significantly lighter and less bulky than zoom lenses. This detail, which may seem trivial, will become more and more important as you become a real photo aficionado. Of course, it's not the same to wear a lens that weighs twice as much as another one around your neck (or over your shoulder or in your backpack) if you have to carry it for hours.

Another issue associated with size is that because they are smaller, these lenses are also more discreet, allowing them to go relatively unnoticed in certain photo situations that require it. Like, for example, street photography where you don't want to attract attention to better capture the essence of a city street.


Another aspect to mention is the reliability of fixed focal length lenses, and I'm not saying here that the photos are more reliable, although it is true that since they have fewer lenses, they produce less geometric distortion as well. What I am saying here is that zoom lenses have certain mechanical elements that allow you to move from one focal length to another. These mechanisms, normally based on gears or other elements, are usually made of plastic to reduce costs, so they often end up getting damaged. They cause the lenses to lock into certain positions or, in the best case, to play with the focal lengths.

Fixed focal length lenses do not have these mechanisms, so the possibility of them getting damaged and damaging your equipment is largely reduced, making them more reliable.

In short: the more mechanisms there are, the more likely it is that something will get damaged.

Versatility of fixed focal length and zoom lenses

This is perhaps where zoom lenses have an advantage over fixed focal length lenses, since the ability to choose from several focal lengths gives them more versatility. But this reality can change since with a fixed lens, you can also zoom. Yes, you can! How can you do that? Well, by moving closer or further away from the subject to be photographed. This is a "manual" zoom.

Just by changing the position, you can achieve almost the same results as with a zoom lens. You will not be able to move closer or further away in very few cases, especially since we are dealing here with introductory zoom lenses, i.e. cheap and with relatively short zomms.


Starter kit lenses are often offered at fairly low prices and are often even "offered" by the manufacturers. Fixed focal length lenses with high brightness are more expensive, especially if you go from f/1.4 to f/1.2. But there is a segment of fixed focal length lenses with apertures around f/1.8 that are excellent value for money and affordable for everyone. Look at brands like Canon, Nikon, Sony or Pentax, all of which have a 50mm f/1.8 lens with a price tag around 100-130 euros.

So, considering the price and the many advantages that fixed focal length lenses have over zoom lenses, we strongly advise you to buy them as they will help improve the quality of your shots.

Available fixed focal length lenses

There are many fixed focal length lenses available depending on the type of photo you want to take, from wide angle to telephoto, but we recommend the focal length range from 35mm to 50mm, both for Full Frame and APS-C cameras, because of their greater versatility and their very good quality-price ratio.

35mm Focal Length

This is the ideal lens for street photography because it's wide enough to include a lot of the environment, in addition to the featured object. It is also a great lens for indoor photography, where you want to capture an intimate scene with little light, such as the interior of an artist's studio, for example, or the room of a bride who is putting on her dress.

For portraits, its use is rather limited because you will have to get very close to your subject. You can always look for more medium shots and include them in the environment, for more striking and evocative results since you will not only capture the "who is it" but also include the "what is it doing". This will make the portraits all the more interesting.

As we said, their angle of view encompasses a wide area, so they're great for landscapes. Not to mention that with their large aperture, they will also be perfect for night landscapes and selective blurring of objects in the foreground of the scene.

50mm Focal Length

This is the lens that comes closest to the angle of vision of the human eye, allowing you to take pictures with zero distortion. This approximation to the human angle of view allows for even greater simplification of the lens and provides even greater quality in terms of sharpness and resolution.

This is quite an interesting lens for portraiture, especially if you use cameras with a reduction factor (APS-C). You will get interesting foregrounds and very good medium shots as it will allow you to add many elements to your characters. And it will also allow you to photograph details because without being a macro lens, it will bring you significantly closer to different elements and highlight the essential areas of the scene if you play on the selective blur.

For landscapes, it is a little more limited because it is not very wide angle but conversely, it will allow you to take beautiful panoramic shots, especially if you place the camera vertically. You can use it to bring out elements of the landscape that appear quite distant in wide-angle photos.

Other focal lengths

Other fixed focal length lenses similar to these and equally versatile are their equivalents for APS-C sensor cameras. Thus, you have, for example, 20 mm lenses that are almost equivalent to 35 mm on APS-C cameras or 30 mm that are almost equivalent to 50 mm.

One of my favorite lenses for my Canon that is almost at an intermediate level is the EF 40mm f/2.8 STM Pancake. As noted, it is midway between the 35mm and 50mm and has the respective advantages of both. Moreover, its extremely small volume and weight almost allow me to store it in my coat pocket, once mounted on my Canon 6D. Mounted on it, it would almost go unnoticed. The STM focus is relatively faster and quieter than the USM, which also allows me to shoot video with barely any noise. Its brightness isn't as strong as the 50mm f/1.8 or f/1.4, but its reduced weight and bulk make it possible to shoot camera-in-hand with fairly slow shutter speeds, while almost correcting for that stop down light it presents.