Overall performance is good. Canon 35mm F 1.4L USM evaluation.

IT 168？ Editor's note: Canon EF 35mm F 1.4L USM lens is one of the early L lenses. First, it has attracted the attention of many photographers. Although there is a saying that there is no weakness in focusing, Canon EF 35mm F 1.4L USM is also facing such a huge impact with the gradual improvement of lens quality in some sub-factories. What I bring to you today is that in the comparative evaluation of three EF bayonet lenses of @ Image Rubik's Cube, Canon EF35mm F 1.4DG HSM, Canon EF 35mm F 1.4L USM and Canon EF 35mm F2 are the evaluation contents of USM.

"Model Description"

Canon EF 35mm F 1.4L USM

EF: Suitable for 35mm Quan Huafu image field.

35mm: The focal length on Quan Huafu is 35mm, which is equivalent to 56mm on APS-C frame.

F 1.4: maximum aperture F 1.4.

L: Canon's high-end lens series has a red decorative line in front of the lens, which is also called "red circle lens".

USM: Canon's ultrasonic focusing motor, here is the ring focusing motor.

"Product introduction"

Canon EF 35mm F 1.4L USM was released in199865438+February, and appeared at the same time as EOS-3 film SLR camera. It is one of the earliest L-shaped lenses in service. Together with EF/KOOC-0/35mm F2L USM (/KOOC-0/996) and EF/KOOC-0/00-400mm F4.5-5.6L IS USM (/KOOC-0/998), it is an L-shaped lens with updated sound.

After the latest round of price adjustment, the licensed price of EF 35mm F 1.4L USM has dropped to about 9000 yuan. The second-hand market has been impacted by Sigma's 35mm F 1.4 DG HSM, which is also greatly reduced compared with previous years.

"Configuration Description"

Mirror group structure: nine groups 1 1 lens structure, with telescopic field of view, and the penultimate lens is an aspheric lens. Compared with the number of special lenses, the "stacked" Sigma 35mm F 1.4 DG HSM is very common.

▲ Mirror group structure of Canon EF 35mm F 1.4L USM

Focus design: The floating back focus (RF) design is adopted, and the front end of the lens does not rotate when focusing. Equipped with USM ring ultrasonic motor, it supports full-time manual focusing.

Close-up capability: the nearest focal length is about 30cm, and the maximum magnification is about 0. 18 times.

Aperture blades: 8 blades, non-circular blades.

Coating: Optimized hyperspectral coating.

Filter aperture: 72mm, one level larger than Nikon and Sigma lenses of the same specification.

Control function: AF/MF switching.

Lens workmanship: made of metal and composite materials.

Size and weight: 79mm×86mm. 580 grams.

Accessories: petal-shaped hood (EW-78C) and soft bag are standard, and there is flocking inside the hood.

▲ Size comparison of three 35mm fixed-focus lenses

▲ Diameter comparison of three 35mm fixed-focus lenses.

"image quality performance"

Distortion:-1.45% (very slight)

Scattered: slight

Dark corner: basically disappears after reaching F8.

Resolution:

The resolution test uses Sony A7R and EOS-E electronic adapter rings. When shooting, it is stored in RAW format, and then converted to JPG with Adobe Camera Raw 8.5, and the sharpness is set to zero. ISO 12233 4000 line test card is used as the resolution test standard, and Imatest 3. 10 software is used to read and analyze. During the test, four points are selected on the screen, and the distances from the center of the screen are 17% (phase field radius), 30%, 60% and 80% respectively. For users in APS-C format, 60% of the points can be regarded as edge areas in APS-C format.

The minimum aperture of Canon EF 35mm F 1.4L USM is F22, but on A7R, the image quality will obviously decrease from F8 to F 1 1, so we choose F 16 as the minimum aperture in the test.

▲MTF50 test results

▲MTF50 test results

▲MTF30 test results

▲MTF30 test results

"How to read MTF curve"

We were very surprised by the test results of Canon EF 35mm F 1.4L USM. Its 30% score is higher than 17% and its 80% score is higher than 60%, which violates the common sense that the farther away from the center of the picture, the worse the picture quality. Because three lenses are tested at the same time, the interference of standards and lighting is eliminated. We have repeated the test several times, and the result is still that the edge score is higher than the center score. Finally, we found evidence from Canon's official MTF chart, which proved that our test was indeed accurate.

In the MTF diagram, 10 line /mm reflects the contrast of the lens, and 30 line /mm reflects the resolution of the lens. Our test data focuses on resolution, so we mainly focus on the performance of 30 lines /mm, which is the thin line in Canon's official MTF diagram. 5, 10, 15, and 20 on the abscissa in the MTF diagram represent the distance from the center of the picture. The diagonal of 35mm Quan Huafu is about 43mm, so the longest radius is 21.5mm. In our test, 17%, 30%, 60% and 80% represent the length of relative radius, which is about 3.7mm, 6.5mm, 13mm and/kloc-0 after conversion.

With the above preparations, let's take a look at the official MTF curve of Canon EF 35mm F 1.4L USM. The two thin solid lines in the picture do not descend smoothly. They first have a peak around 5mm, and then around 17mm, the blue thin line representing F8 aperture has a more obvious peak-the highest point of the peak is even higher than the starting point of the whole thin solid line, which is the performance of the most central area of the picture. This is basically consistent with our test data.

There are many possibilities for this. Later, we will ask another core member of @ Image Rubik's Cube @ Pseudophotographer Xiao Q to explain why the edge resolution of the picture is higher than the central resolution.

▲ Canon EF 35mm F 1.4L USM official MTF curve.

"focusing performance"

Canon EF 35mm F 1.4L USM is equipped with USM ring ultrasonic motor, which can drive the focusing lens group quietly and stably, and the actual focusing speed and stability are ideal.

"test notes"

According to the test data, Canon EF 35mm F 1.4L USM needs to reduce the aperture to F4.0-5.6 to achieve the highest image quality. Starting from F2.8, 80% of the picture quality is higher than 60%, that is, the edge performance is better than the sub-edge performance. Sticking on APS-C model, 60% becomes the edge of the picture, and the imaging at this time conforms to the characteristics of most lenses.

By testing Canon EF 35mm F 1.4L USM, let me re-examine the value and significance of the official MTF curve. Although this is not particularly helpful for practical use, it can improve your understanding of lens temper for equipment lovers.