Offering a super long reach beyond what most kit lenses offer, a telephoto zoom lens is a logical choice for photographers looking for a second or third lens. And if you need a small, lightweight, relatively affordable option, the RF100-400mm f/5.6-8 IS USM, may be just what you are looking for. A train photographer took the lens with him up mountains and on forest treks to catch different trains journeying through nature. He shares his experiences here. (Reported by: Atsushi Kubota, Digital Camera Magazine)

Amazingly light for a 100-400mm lens

Versatile 100-400mm focal length range in a compact, lightweight body

I was amazed by the features and specifications of the RF100-400mm f/5.6-8 IS USM when I first learned about it. It offers the same focal length range as Canon’s L-series EF100-400mm lens, but at a friendlier size, weight, and price.

For a zoom lens that covers 100mm to 400mm, the lens is unexpectedly compact and lightweight. This is something I was grateful for, since railway photography often involves a lot of walking around, and even long hikes and challenging upslope climbs to find the best vantage points. I tried this lens mounted onto the EOS R6, and the entire combination weighed only around 1.3kg—extremely light and easy to move around with. It fit into a small camera bag together with the RF24-105mm f/4-7.1 IS STM. Together, these two lenses were enough to cover most rail photography scenes, from quick snapshots of moving trains that I chanced upon, to works that required more effort.

100mm to 400mm is a rather versatile focal length range for outdoor photography. At 100mm, you can include more scenery whereas 400mm allows you to close in on specific parts of the train.

 

EOS R6 + RF100-400mm f/5.6-8 IS USM @ 400mm, f/11, 1/125 sec, ISO 3200, WB: Daylight

The 400mm end of the lens made it possible to catch this head-on shot of a train exiting the tunnel, all while standing in a safe position just outside a curve in the train tracks. This was shot just after the rain, and the soft foreground bokeh created from the dewy foliage in front expresses the depth of the forest.

An extra 100mm can change the visual impact of an image, and it’s not just because the subject looks closer! Learn about this in:
Lens FAQ #7: What is the difference between a 200mm and 300mm telephoto lens?

Image quality and bokeh

Excellent visual quality: Sharpness, clarity, lovely telephoto bokeh

The lens configuration includes one Ultra-low Dispersion (UD lens) and one aspherical lens, which contributes to its sharpness and excellent contrast. The details of subjects are rendered faithfully.

The soft and fluffy bokeh quality should delight users who want incorporate telephoto bokeh into their images. 

EOS R6 + RF100-400mm f/5.6-8 IS USM @ 135mm, f/8, 1/3200 sec, ISO 800, WB: Daylight

The lens’ portability and easy manoeuvrability make it suitable even for snapshots from a station platform like this one. The susuki grass glowing in the soft, even lighting and the train conductor who has popped his head out of the window are depicted clearly, yet at the same time, the mountains at the back and the steam from the steam locomotive are blurred into gentle bokeh.

EOS R6 + RF100-400mm f/5.6-8 IS USM @ 100mm, f/8, 1/3200 sec, ISO 800, WB: Daylight

One basic type of railway photo is the roster shot, where the head of the train all the way to its rear fills the entire frame. The RF100-400mm f/5.6-8 IS USM also covers the most common focal lengths used for such shots. The sharpness and detail of the lens’ rendering was impressive—I expected no less from an RF lens. The blue sky was rendered with clarity, and the colours of the train carriages were faithfully reproduced. The AF system swiftly found, locked onto and tracked the head of the train, helping to catch picture-perfect moments.

Note: Maximum apertures

The RF100-400mm f/5.6-8 IS USM is a variable aperture zoom lens, which means that the maximum aperture changes depending on the focal length. Here’s what I noticed regarding the maximum aperture at some key focal lengths.

To some photographers, the variable maximum aperture of f/5.6 to f/8 (where maximum aperture f/5.6 is effective only from around 100mm to 113mm) may seem too dark. However, as this lens is good even at its maximum aperture, you don’t have to stop down for better-quality images. Noise also shouldn’t be an issue when paired with a camera capable of relatively clean high ISO speed images such as the EOS R6.

Image stabilisation and AF

Fast, precise autofocusing; reliable image stabilisation

AF was fast and accurate. When shooting roster shots (see above) at 100mm, where you need the focus to lock onto the head of the approaching train quickly before it chugs out of reach, the AF was decisive and followed the head of the train tenaciously.

For one scene, I turned on the Face Detection + Subject Tracking Priority AF area mode on the EOS R6 to shoot a steam locomotive. From the time the camera first acquired focus on the train when I spotted it at 400mm, all the way to when I zoomed out to 100mm to change the composition, the train was kept in precise focus.

Optical IS helps you to catch sharp images even when changing the composition
The lens is equipped with a built-in Optical Image Stabilizer (Optical IS) which corrects camera shake by up to 5.5 stops' equivalent (up to 6 stops' equivalent when used with a camera with In-Body IS such as the EOS R6). This proved exceptionally useful for scenes that required making quick changes to the composition, where the slightest camera shake could cost you a fleeting photo opportunity. It also allowed me to take stable handheld shots, which would usually be challenging at longer telephoto lengths.

Extenders

Support for extender use across the entire focal length range

EOS R6 + RF100-400mm f/5.6-8 IS USM with Extender RF1.4x @ 560mm, f/11, 1/320 sec, ISO 800, WB: Daylight

Another major plus of the RF100-400mm f/5.6-8 IS USM is that it supports the use of extenders over the entire focal length range, so you can “add” extra reach when you need it. With the EOS R5 and EOS R6, you still enjoy the benefits of AF, especially since these cameras support a wide AF area even when using the Extender RF2x. The image above was shot with the Extender RF1.4x, which extends the focal length to up to 560mm. With the Extender RF2x, you get to shoot at up to 800mm! This will probably be useful for photographing subjects like bullet trains, where you need to put even more distance between yourself and an oncoming train for safety purposes.

 

A lens full of potential beyond just train photography

Besides genres such as trains, wildlife, and landscapes, the RF100-400mm f/5.6-8 IS USM should also benefit occasions closer to home, such as a child’s recital or school sporting events. With its small size, it should remain relatively unobtrusive. I imagine it will be quite satisfying to be able to capture super telephoto closeups of your child in action, from the gaps between fellow spectators in the stands!

EOS R6 + RF100-400mm f/5.6-8 IS USM

Key specifications and configuration

Key specifications

Lens construction: 12 elements in 9 groups
No. of aperture blades: 9
Minimum aperture: f/32 (at 100mm), f/45 (at 400mm)
Closest focusing distance: 0.88m (at focal length 200mm)
Maximum magnification: 0.41x (at focal length 400mm)
Filter diameter: 67mm
Size: φ79.5 x 164.7mm (retracted）
Weight: approx. 635g

Lens hood: ET-74B (sold separately)

Lens configuration

A: UD lens element
B: Aspherical lens element

What else can you do with a telephoto lens? Get some ideas in:
5 Things to Try with a Telephoto Lens