Significant enhancements have been made to the new EF50mm f/1.8 STM, the successor model to the best-selling EF50mm f/1.8 II. In the second article of this series that tests the capabilities of this much-talked-about lens, I will report on its expressive power as observed in the actual shots I have taken. (Reported by: Takeshi Ohura)

Testing the bokeh effect created by the circular aperture diaphragm

The number of blades in the diaphragm blade unit has increased from five on the predecessor model to seven on the EF50mm f/1.8 STM. The specs are also updated with the use of a circular aperture diaphragm. Bokeh created by the lens is natural, and the transition from the point in focus toward the large blur is smooth. At the same time, the defocused subjects blend harmoniously to produce a softer depiction than that by its predecessor.

As with the background blur, foreground blur is also natural, suggesting that there is well-balanced control of the occurrence of spherical aberrations. It is likely that many users will employ the EF50mm f/1.8 STM frequently to create bokeh effects because of its angle of view, and I believe this lens is capable of producing satisfactory results as expected.

Photo taken at the maximum aperture and from the closest focusing distance (approx. 35cm).

EOS 5D Mark III/ Aperture-priority AE (f/1.8, 1/2,000 sec., EV +0.7)/ ISO 100

Photo taken at the maximum aperture and from a few metres away.

EOS 5D Mark III/ Aperture-priority AE (f/1.8, 1/4,000 sec., EV +0.3)/ ISO 100

Photo taken at f/2.8 and from a few metres away.

EOS 5D Mark III/ Aperture-priority AE (f/2.8, 1/1,250 sec., EV +0.3)/ ISO 100

Photo taken at f/4 and from a few metres away.

EOS 5D Mark III/ Aperture-priority AE (f/4, 1/640 sec., EV +0.3)/ ISO 100

Significantly enhanced backlighting resistance with the new coating and flare cutter

Regardless of whether the sun is included in the composition or just outside of it, we can tell from the examples that there is no serious ghosting or flare. Although no changes were made to the lens construction of the EF50mm f/1.8 STM, a new coating has been adopted to optimise the digital characteristics. Furthermore, thorough measures have also been introduced to prevent internal reflection, such as the flare cutter feature to eliminate unwanted incident light. These efforts have contributed to the reduction of the ghosting and flare effects.

Backlit shot with the sun included in the composition.

EOS 5D Mark III/ Aperture-priority AE (f/5.6, 1/8,000 sec.)/ ISO 100

Backlit shot with the sun excluded from the composition.

EOS 5D Mark III/ Aperture-priority AE (f/5.6, 1/3,200 sec.)/ ISO 100

With the 35cm closest focusing distance, you can get even closer to your subject

Next, let's look at the depiction power of the EF50mm f/1.8 STM when taking close-up shots. To make the best of its 35cm closest focusing distance, I took street snapshots. Here is how the lens performed.

EOS 5D Mark III/ Aperture-priority AE (f/2, 1/1,000 sec., EV +0.3)/ ISO 100

With the closest focusing distance reduced to 35cm on the EF50mm f/1.8 STM, this lens allows you to draw the subject closer than before for a larger view. The transition from the plane in focus toward the bokeh is smooth.

EOS 5D Mark III/ Aperture-priority AE (f/2.8, 1/1,600 sec.)/ ISO 100

Here, I set the aperture to f/2.8, which is a little more than one stop lower the maximum setting. As the lens adopts a circular aperture diaphragm with seven blades, the bokeh effect created is, as the name suggests, perfectly round with no corners.

EOS 5D Mark III / Aperture-priority AE (f/3.2, 1/100 sec.)/ ISO 1600

I stopped down the aperture slightly to f/3.2, and the resulting image is natural with no aberrations such as astigmatism. The shorter closest focusing distance allows you to get up close to the subject, even for close-up photos of the kind shown above.

EOS 5D Mark III/ Aperture-priority AE (f/2.8, 1/3,200 sec.)/ ISO 100

This photo was taken near the closest focusing distance. The area that is in focus appears sharp. Judging from the background of the shot, the result might be better if I had narrowed the aperture slightly further.

Astoundingly sharp depiction of the area in focus

Let's now see how the EF50mm f/1.8 STM fares in mid- and long distance shots.

EOS 5D Mark III/ Aperture-priority AE (f/5.6, 1/400 sec., EV -0.3)/ ISO 100

Narrowing the aperture to f/5.6 increases the apparent resolution and contrast substantially. The image looks crisp, including the four corners that lack sharpness at the maximum aperture.

EOS 5D Mark III/ Aperture-priority AE (f/4, 1/1,600 sec.)/ ISO 100

The foreground blur looks natural. I set the aperture to f/4, but there is no noticeable peripheral light fall-off as far as this shot is concerned. The sharpness of the area in focus is also excellent.

EOS 5D Mark III/ Aperture-priority AE (f/5.6, 1/1,000 sec.)/ ISO 100

There is sharpness and dimensionality in the overall expression. The aperture setting I used was f/5.6. Though not comparable to that at the centre of the image, expression of the peripheral areas is still considered satisfactory.

EOS 5D Mark III/ Aperture-priority AE (f/2.8, 1/2,000 sec., EV +0.3)/ ISO 100

Although the level of contrast produced by this lens may not be as outstanding as other prime lenses, it is sufficient for this class of lenses. As can be seen from the example, there is a slight amount of barrel distortion in the pole on the left.

EOS 5D Mark III/ Aperture-priority AE (f/2, 1/6,400 sec., EV -0.7)/ ISO 100

Taken at f/2. With an aperture value that is brighter than that of a large-aperture zoom lens, you can enjoy greater diversity when creating bokeh effects in your shots.

EOS 5D Mark III/ Aperture-priority AE (f/5.6, 1/1,000 sec., EV -0.7)/ ISO 100

The texture of the subject is faithfully reproduced with a high level of contrast and sharpness characteristic of prime lenses. The resulting image is refined with a realistic feel.

Astoundingly sharp depiction of the area in focus

After taking the test shots, my conclusion is that the EF50mm f/1.8 STM is the befitting successor of the EF50mm f/1.8 II, which is well loved by entry-level users, advanced amateurs who have their own views, as well as professionals. With features such as a coating optimised for digital cameras, enhanced exterior texture and smooth AF made possible by the STM, I am certain everyone will be satisfied with what this lens has to offer.

As a user of the predecessor models, the EF50mm f/1.8 and EF50mm f/1.8 II, and based on the result of the tests, it goes without saying that I will be getting the EF50mm f/1.8 STM for myself too.

This lens appears to be set to offer even greater versatility than its predecessors, both as a user-friendly standard lens when you are using a full-frame EOS camera, and as a medium-telephoto lens for magnificent close-up shots when you are using an APS-C sized EOS camera.