The Sony 100-400mm Lens Thoughts and Field Test

A Post By: Suzi Pratt

The Sony 100-400mm f/4.5-5.6 lens was announced in 2017 along with the Sony A9. Both the camera and lens were highly anticipated by many professional photographers because they offer features that were long lacking in the Sony E-mount lineup. In particular, this lens with its far-reaching focal length appeals to sports and wildlife photographers. But with a price tag of just $2,500, this lens is pretty accessible to amateur and hobby photographers as well. In this post, I’ll give an overview of specs for this lens plus my thoughts after using it to photograph birds.

Lens Specs

The Sony 100-400mm lens is a variable aperture lens for Sony full-frame cameras. You can use it on Sony crop-sensor cameras, but its physical size might make it awkward to shoot with, especially if used on a tiny camera like the Sony a6000. There is optical image stabilization (OIS) that provides a degree of stability when shooting handheld photos and videos with this lens.

Size-wise, it has a diameter of 3.7 inches and a length of 8.07 inches. The lens weighs approximately 49.2 ounces or 1395 grams. If those numbers don’t mean much to you, the 100-400mm is a very similar size and weight to the Sony 70-200mm f/2.8. Some might consider this lens to be big and bulky, but for the focal range, I think its size is reasonable and comparable to similar lenses made by other manufacturers.

One thing is for sure: you’ll get the best quality if you use a monopod with this lens.

In terms of physical buttons, there are two that are particularly helpful. One button is a focus range limiter that restricts the range of distances the camera will attempt to lock focus on. This boosts the speed of focus as well as focus accuracy, preventing focus hunting. The other feature is the ability to adjust zoom smoothness to prevent the lens from sliding out when carried.

Best uses

With a variable aperture of f/4.5-5.6, this isn’t a particularly fast lens, so it is best used in ample lighting conditions. Think broad daylight scenarios such as sports, nature, and wildlife. Portraiture may even work well with this lens, although most swear by the 70-200mm f/2.8 for people shots.

For the field test, I paired the 100-400mm with the Sony A7rIII. Using a camera with more resolution (42.4 megapixels) is especially beneficial as the extra megapixels allow you to crop in. You can also take advantage of shooting in APS-C mode on the camera, which effectively doubles your focal range. The A7RIII can also shoot at up to 10 frames per second, and has the newly added animal eye autofocus tracking, making this camera very ideal for wildlife photography. Both the camera and lens have weather sealing. However, I did not test this feature on this shoot.

Size comparison of the Sony 100-400mm to the Fujifilm 100-400mm.

Lens alternatives

If you plan to shoot in low lighting, the Sony 300mm f/2.8 or 400mm f/2.8 lens will be more appropriate. However, those lenses are $5,800 and $12,000 respectively, so you’ll need deep pockets. Considering these prices, $2,500 for the 100-400mm is quite reasonable. You may even want to consider the newly announced 200mm-600mm f/5.6-6.3 lens, which is just $2,000, but considerably larger in size.

So how was it?

I took the 100-400mm on a weekend trip to go birding in Eastern Washington.

Birds were aplenty, and this lens excelled at shooting them in daylight conditions at every focal length. Its size and weight made it possible to shoot handheld. But for extended periods of time and for optimal performance, it was best used when mounted on a monopod.

Performance-wise, autofocus was fast and accurate. Animal eye autofocus (new to the Sony A7RIII and several other camera bodies) was hit or miss for birds, but I’ve heard that it currently works best on dogs and cats.

Would I buy this lens?

If I was an avid wildlife and birding photographer, I absolutely would. The price of $2,500 is more than reasonable for a lens with this focal range. Although, third-party lens makers such as Sigma and Tamron are producing some stellar pieces of glass lately and I would love to see them make a version of this lens for Sony E-mount.