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Products >> All Products In Focus: Key Specifications of RF Lenses- Part6

RF100mm f/2.8L Macro IS USM: 1.4x Macro with Adjustable Bokeh Flavour

On 14 April 2021, Canon announced the RF100mm f/2.8L Macro IS USM, its first true macro lens for the RF mount. The lens design harnesses the flexibility afforded by the RF mount’s large mount diameter and short back focus distance to achieve new possibilities, such as a maximum magnification of 1.4x and a Spherical Aberration (SA) control ring that allows users to achieve soft focus effects. Read on to learn more about this new red-line (L-series) medium telephoto macro lens that realises both excellent image quality and unprecedented functionality.

Key features of the lens

 

World’s first lens in its class* to achieve 1.4x magnification

The RF100mm f/2.8L Macro IS USM is a 100mm medium telephoto macro lens. Macro lenses in this class usually have a maximum magnification of 1x (life size), which means that a subject that is 1cm long will be depicted as 1cm on the image sensor.

To capture close-ups of a subject so that it fills more of the frame, your first instinct would be to move closer to it. However, on all lenses, there is a closest focusing distance, i.e., a limit on how close you can be before the lens becomes unable to focus. On the RF100mm f/2.8L Macro IS USM, this closest focusing distance is 26cm, shorter than the 30cm on the EF100mm f/2.8L Macro IS USM. This achieves a larger maximum magnification of up to 1.4x—more than life size—even while retaining the same focal length.

 

Difference in shooting distance, working distance, and magnification

On the RF100mm f/2.8L Macro IS USM, you can achieve the usual life size 1.0x magnification from focusing distance 28cm. Moving just 2cm closer to the 26cm closest focusing distance lets you achieve the 1.4x magnification. The working distance for both magnification ratios is 11.2cm and 9.2cm respectively, leaving enough space in between to ensure sufficient lighting.

1.0x

1.4x

How did Canon manage to achieve the world’s first* 100mm macro lens capable of up to 1.4x magnification? The answer lies in the characteristics of the RF mount, namely, the large mount diameter and short back focus distance, which allowed more flexibility in optical design. The resulting changes to the design and AF drive dynamics of the focus and floating lens groups made it possible to carry out fast, precise focusing from nearer than before.

* Of all AF interchangeable lens for full-frame mirrorless cameras. As of 13 April 2021, according to a Canon survey.

 

The electronic floating focus control system: Achieving more than just fast, accurate AF

On the RF100mm f/2.8L Macro IS USM, the autofocus (AF) is driven by two independent Nano USMs that make possible an electronic floating focus control system where the focusing lens group and the floating lens groups are controlled separately. This enables the RF100mm f/2.8L Macro IS USM to balance improved functionalities such as a shorter closest focusing distance and spherical aberration control alongside core performance qualities such fast, high-precision AF. The electronic floating focus system also helps to reduce focus breathing, which causes the angle of view to change during focusing.

The Nano USM (Ultrasonic Motor) is characterised by its capacity to perform both quick and precise movements, which are unique to a linear ultrasonic motor. This makes it capable not just of swift subject acquisition when shooting still images but also seamless subject tracking when shooting videos, therefore ensuring that viewers don’t feel uneasy when watching the video playback. Indeed, the AF capabilities of the RF100mm f/2.8L Macro IS USM also make it an excellent video lens.

 

Know this: What is an electronic floating focus system?

The rendering performance of a lens is usually not the same across all shooting distances—even for prime lenses with their reputation for being particularly sharp. At the design stage, the engineers will first determine a benchmark shooting distance, and then correct lens aberrations so that the image quality is the best at that “sweet spot”. This results in a reduced correction effect at shooting distances outside this sweet spot.

One of the solutions for this issue is to adopt a floating lens system, which involves moving a lens group other than the focusing lens group during focus adjustment. Such a system also improves lens aberration correction and close-up shooting capabilities.

While the EF100mm f/2.8L Macro IS USM had a mechanical system that used barrel-shaped cam gears, allowing movement only along one track, the Nano USMs on the RF100mm f/2.8L Macro IS USM, which are driven by high-performance microprocessors, can move on a variety of tracks. This, together with the RF mount design that affords more space to move the floating lens group, contributed to the significant improvement in functionality and performance on the RF100mm f/2.8L Macro IS USM.

 

SA control ring: Create soft focus images when you wish

A unique feature on the RF100mm f/2.8L Macro IS USM is the SA (Spherical Aberration) control ring, which utilises the electronic floating focus system to allow users to control the degree of spherical aberration correction.

Spherical aberration is usually believed to cause image quality deterioration, but it also affects how bokeh is rendered, i.e. its “flavour”. For example, the unique “bubble bokeh” with hard outlines rendered by vintage lenses, considered beautiful by some people, partly results from the under-correction of spherical aberration due to technological limits in the past. The more spherical aberration is corrected, the smoother the bokeh rendered, which eventually results in the soft focus effect.

On the RF100mm f/2.8L Macro IS USM, the use of Nano USMs makes it possible to control the floating lens group independently from the focusing group. This enables unprecedented control over the degree of spherical aberration correction without affecting the focus position. By turning the SA control ring, users can change how the bokeh in front of and behind the focal plane looks—whether it’s hard, vintage-style bokeh or soft, buttery bokeh—providing greater variety of expression.

 

The SA control ring

Turning the SA control ring towards ‘+’ or ‘-’ moves the floating lens group, so that you can intentionally allow spherical aberration.

SA Control 0

This is the standard look, with spherical aberration reduced throughout the entire image

 

SA Control -4

Turning the SA control ring towards ‘-’ softens the outlines of the bokeh behind the focal plane and hardens the outlines of the bokeh in front of the focal plane.

SA Control +4

Turning the SA control ring towards ‘+’ hardens the outlines of the bokeh behind the focal plane and softens the outlines of the bokeh in front of the focal plane.

*The effect of the SA control ring (the amount of variability in spherical aberration) varies depending on the shooting distance. As the shooting distance decreases from the infinity focusing range to when the lens achieves life size (1x) magnification, the amount of variability increases. However, due to structural factors, the spherical aberration will not change at the 0.26m closest focusing distance.

 

EOS R5/ RF100mm f/2.8L Macro IS USM/ FL: 100mm/ Aperture-priority AE (f/2.8, 1/3200 sec)/ ISO 800/ WB: Daylight/ SA Control

Using the SA control ring to create the soft focus effect can give your images a unique look—even for still life, flower and portrait photography.

 

Hybrid IS for stabler macro images; up to 8 stops’ image stabilisation

When a subject is more than a certain distance away, angular (rotational) camera shake is more likely to occur. The usual IS (Image Stabilizer) system is designed to compensate for this kind of camera shake. However, during close-up shooting, angular camera shake is less likely to occur. Instead, shift camera shake, which occurs when the sensor plane is moved in a parallel direction to the subject, becomes more obvious. The RF100mm f/2.8L Macro IS USM is equipped with the Hybrid IS (Hybrid Image Stabilizer) system, which compensates for both angular and shift camera shake. Hybrid IS can provide as much as up to two shutter speed stops’ equivalent image stabilisation when shooting close-up at life size magnification.

When shooting from a normal shooting distance, the in-lens Optical IS system provides up to five shutter speed stops’ equivalent image stabilisation. When attached to a camera with In-Body IS such as the EOS R5 or EOS R6, Coordinated Control IS is active, correcting camera shake by up to eight shutter speed stops’ equivalent.

EOS R/RP
EOS R5/R6
Optical IS
Coordinated Control IS
(Optical + In-Body IS)
Up to 5 stops
Up to 8 stops

*According to CIPA standards; in yaw/pitch directions

 

Tried and tested: A handheld urban nightscape

The urban nightscape images below were shot handheld at shutter speed 1 second to test the IS effect.


IS OFF/ Shutter speed: 1 sec

When IS was turned off, all the images had camera shake.

 

EOS R (Optical IS up to 5 stops)/ IS ON/ Shutter speed: 1 sec

With the EOS R and Optical IS, camera shake seems to have been effectively suppressed in the overall image. However, when we zoom in, there is visible reduction in sharpness due to camera shake.

 

EOS R5 (Coordinated Control IS up to 8 stops)/ IS ON/ Shutter speed: 1 sec

With the EOS R5 and Coordinated Control IS, the image is still sharp even when we zoom in. It looks as though it were shot with a tripod!

Learn more about the kinds of shots made possible by In-Body IS here

 

The excellent image quality and durability true to an L-series lens

The EF100mm f/2.8L Macro IS USM was well-acclaimed for its excellent image quality. The RF100mm f/2.8L Macro IS USM, besides incorporating various new functionalities, realises the same excellent optical performance.

While it does not use any special coatings or lens elements, it does use the same kind of glass used in fluorite lenses—high-refractive glass with unique anomalous dispersion characteristics—which effectively corrects chromatic aberrations. The lens coatings and shapes of the lens elements are optimised to reduce ghosting. These, together with the smudge-resistant fluorine coating on the front lens surfaces and the dust- and drip-resistant design ensure the excellent optical performance and durability that equips an L lens to handle various shooting environments.

 

Lens construction

Smudge-resistant fluorine coating on the front lens surfaces

Dust- and drip-resistance design

With the various rings, switches, and other moving parts weather-sealed, the lens is designed to prevent dust and water droplets from entering, increasing its reliability.

 

Ring-type tripod mount for better stability, easier switching of camera orientations

For more secure tripod mounting, a new ring-type tripod mount that provides better stability is also available (sold separately). Attaching it to the barrel of the RF100mm f/2.8L Macro IS USM allows the camera and lens to be mounted at the centre of gravity, improving stability. When the lock screw is loosened, the camera can be rotated around the lens, allowing the photographer to change the orientation of the shot without having to tilt the tripod head.

 

Ring-type Tripod Mount E(B): Sold separately

 

When using a tripod, changing from a horizontal composition to vertical one usually involves tilting the tripod head. This movement causes the shooting position to change significantly, and having to re-adjust the entire setup can be cumbersome especially when shooting macro. The ring-type tripod mount allows the camera to be rotated while keeping the lens still, so that the subject stays in the centre of the composition and the optical axis is maintained even while the orientation of the shot changes.

 

RF100mm f/2.8L Macro IS USM

Key specifications

Lens construction: 17 elements in 13 groups
Closest focusing distance: 0.26m
Maximum magnification: 1.4x
No. of aperture blades: 9 (circular blade)
Filter diameter: 67mm
Size: φ81.5 x 148mm
Weight: approx. 730g


Lens hood: ET-73C (bundled)

 

Sample images


EOS R5/ RF100mm f/2.8L Macro IS USM/ FL: 100mm/ Manual exposure (f/3.5, 1/8000 sec)/ ISO 3200/ WB: Auto


EOS R5/ RF100mm f/2.8L Macro IS USM/ FL: 100mm/ Manual exposure (f/3.5, 1/160 sec)/ ISO 400/ WB: 5200K


EOS R5/ RF100mm f/2.8L Macro IS USM/ FL: 100mm/ Manual exposure (f/32, 1/160 sec)/ ISO 6400/ WB: 5700K/ With flash


EOS R5/ RF100mm f/2.8L Macro IS USM/ FL: 100mm/ Aperture-priority AE (f/2.8, 1/400 sec)/ ISO 400/ WB: Daylight/ SA Control


EOS R5/ RF100mm f/2.8L Macro IS USM/ FL: 100mm/ Manual exposure (f/5.6, 1/160 sec)/ ISO 160/ WB: 4800K
Shot at 1.4x magnification

 


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