Testing and Detailed Review of the Lens Canon EF 50 f / 1.8 STM

Testing and detailed review of the lens Canon EF 50 f / 1.8 STM
Lens overview

Today we have a lens on the test, which promises to be a real bestseller. Why? Well, let’s start with the fact that it is a high-aperture “fifty dollars”, which is equally well suited to full-frame and non-full-frame Canon SLRs. Its cost is really low when compared with any other fast fix. Finally, it suffices to recall the popularity of its predecessor, who invariably accompanied any keen “canonist” over the past two decades. So, we meet Canon EF 50mm f / 1.8 STM! This test will begin with a historical retreat. Since we have already mentioned the predecessor lens, this is the time to talk about it in more detail. The legendary Canon EF 50mm f / 1.8 II successfully existed on the market (attention!) A quarter of a century. Its production began in the distant 1990. For plastic case from Western photographers, he received the nickname Plastic Fantastic. But let’s not forget that only the most legendary lenses received their own names. This is a kind of recognition. For thousands of photographers, this particular lens became the first high-aperture optics. And with the advent of the digital era and APS-C format sensors, he was re-trained as a portrait staffer from the “staffer”, which made him even more popular. But let’s be honest: cheap constructive, noisy and slow autofocus, not always perfect sharpness on an open diaphragm and offensive plastic bayonet were objective minuses of this model.


The Canon EF 50mm f / 1.8 STM is an updated, albeit outwardly a bit like its predecessor version of the legendary Plastic Fantastic. Of course, you should not expect a metal case from the budget optics. It is still made of polymeric materials. But the bayonet became metallic – a trifle, but nice!

On the changes in the autofocus system says the very name of the lens. The letters STM indicate the use of stepper autofocus actuator, adapted for video shooting. At this point it is worth staying in more detail. The key difference of the STM drive is the ability to move the lenses at different speeds: when photographing quickly, and when shooting video, slowly, smoothly.

It is impossible to call absolutely silent autofocus: in the process of work, it still emits a barely audible buzz. You can hear it with manual focusing: depending on the speed of rotation of the focusing ring, the sound frequency changes noticeably. After all, the autofocus ring is electronic here. Rotating it, you control all the same STM-drive autofocus. But the reaction of electronics is so fast and accurate that the lack of direct contact with the focusing mechanism is absolutely not felt. There is no problem with manual focusing: sharpness can be brought with precise precision.

In the design of the lens there were other changes. If the predecessor had only five aperture blades, then the Canon EF 50mm f / 1.8 STM had seven. Due to this, when shooting on a closed diaphragm in the area of ​​the bokeh are not formed glares in the form of nuts, they remain round. Such a diaphragm is called rounded. As a rule, a rounded aperture is used in portrait lenses to obtain the softest possible background blur, without distracting elements. Let’s not forget that on cameras with an APS-C format sensor, the Canon EF 50mm f / 1.8 STM lens just becomes a portrait painter.

Rounded diaphragm

During our test, we used the Canon EF 50mm f / 1.8 STM with different cameras: with full-frame Canon EOS 5D Mark III and Canon EOS 5Ds, as well as with the “sprinkled» Canon EOS 750D. One of the goals of such testing was to check the accuracy of autofocus operation. If the photographers had complaints about the previous version of the lens with regard to accuracy, then with the Canon EF 50mm f / 1.8 STM there were no such problems. He focuses exactly where the photographer indicated to him, choosing the appropriate focus point. During the test, both the central and lateral points of the Canon EF 50mm f / 1.8 STM focused without a miss.

 The minimum focusing distance of the Canon EF 50mm f / 1.8 STM is 35 cm from the plane of the matrix. Of course, this is not enough for a full macro shooting. However, a large-scale shooting of flowers, even such small ones as lilies of the valley, will have no problems.

Optical properties

And what about sharpness? Despite the fact that the optical scheme has not changed dramatically compared to its predecessor (all the same six elements in five groups), the Canon EF 50mm f / 1.8 STM clearly added in sharpness. This becomes noticeable from the first frame, regardless of which camera you are shooting. Frankly, at first, out of habit, I covered up the aperture a bit to f / 2-f / 2.8. But it soon became clear that even with cameras with a high pixel density (for example, with the Canon EOS 750D or Canon EOS 5Ds), it is quite possible to shoot at the open aperture. If we talk about the Canon EOS 5D Mark III, then its lens sensor perfectly resolves over the entire frame area even by f / 1.8. Naturally, when aperture sharpness is still slightly increased, disappear barely

If you are shooting on closed diaphragms, then this budget lens can work even with top cameras. For example, at f / 4, it can provide excellent results even with Canon EOS 5Ds. The detail across the entire field of the frame is high, even the smallest elements are distinguishable in the photographs. Click on the photo to open it in a new window in full size. Cityscapes can be considered endlessly, to study the smallest details. And in the pictures with flowers, note the small drops of dew.

When you want an uncompromisingly high quality, close the aperture to f / 5.6 – f / 8. Even the strictest critic will not be able to find fault with the sharpness of the 50-megapixel image taken at Canon EOS 5DS.

The situation with chromatic aberrations has also improved significantly. Of course, on enlarged pictures you will find them. However, the level of aberrations is extremely low even at an open diaphragm. They appear only on the open diaphragm along very contrasting borders (look at the border of the black monument and the bright sky). The image quality is not significantly affected by chromatic aberrations, and when diaphragmed, their level decreases markedly.

There is a slight spherical aberration (visible on the head of the monument). But it appears only at the open aperture and closer to the edges of the frame. Like chromatic, this aberration cannot be detected without a 100% increase.

A significant officially announced change in the optical scheme compared to the predecessor lens was the replacement of the lens coating with the modern Super Spectra. Work in backlight has clearly become more confident. Falling contrast and flare is not formed. The appearance of glare is possible, but only in some cases, when a bright light source is close to the corner of the frame.

When shooting on a full-frame camera on an open aperture, there is noticeable vignetting, which is saved on both f / 2 and f / 2.8. However, already at f / 4 the darkening of the frame angles disappears.

Vignetting test

Evaluation of the bokeh – the image in the area of ​​unsharpness – one of the most difficult tasks, since each photographer in this regard may have his own opinion. Nevertheless, over the years, some conditional criteria have emerged in photography, according to which the lens side can be referred to as “right” or “wrong”. I have to say: the Canon EF 50mm f / 1.8 STM bokeh is not correct. Glare in the area of ​​unsharpness have a contrast, slightly brighter edging.

This trifle causes a rather specific, hard nature of the background blur. If the background is heterogeneous, contains single light sources, then there is a high risk of the appearance of the so-called scale effect, when instead of a blurred circle in the side we see a ring.

Canon EF 50mm f / 1.8 STM can be called an ideal lens for amateur photographer. It is extremely compact and light (only 159 grams), and it works equally well with full-frame and crop cameras. The sharpness that this lens provides is not what you expect from a budget class model. It is high already on the open diaphragm. If to cover a diaphragm, then problems will not be even when shooting on the most exacting cameras to optics. The developers also managed to minimize all possible distortions: chromatic and spherical aberration, parasitic flare and glare. They are present in small quantities, but absolutely do not interfere with getting a quality result. And the vignetting goes away at diaphragm up to f / 4.

Replacing the autofocus motor with a stepper STM drive benefited both precision and focusing speed. In addition, now when shooting video there is the possibility of working with a smooth and quiet autofocus. Although the manual focus ring has become electronic, it is just as comfortable as a mechanical one. Perhaps the most controversial characteristic of the Canon EF 50mm f / 1.8 STM is its bokeh: quite tough, with contrasting highlights. Someone may not like it. However, bokeh is very original and unusual, it can be used as an artistic effect. In any case, in this price category, you definitely will not be able to find a lens with the best optical quality and equally extensive creative possibilities. We recommend the Canon EF 50mm f / 1.8 STM to all owners of Canon Canon SLR cameras for both portrait and photo shooting in any other genres.


  • compact size and light weight;
  • fast and accurate autofocus;
  • Excellent implementation of the electronic focus ring;
  • smooth autofocus when shooting video;
  • high sharpness even on the open aperture;
  • low chromatic aberration;
  • small minimum focusing distance;
  • rounded diaphragm;
  • good work in backlight.


  • quiet but not silent autofocus;
  • spherical aberration (soft effect) is present on the open diaphragm;
  • noticeable vignetting to f / 2.8 inclusive;
  • specific bokeh with hard highlights.

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