Sony FE 100-400mm f/4.5-5.6 Review

Announced alongside the Sony Alpha 9 body, the Sony FE 100-400mm f/4.5-5.6 GM is a crucial addition to Sony’s expanding full-frame E-mount lineup. The last few of years have seen Sony release some beautiful lenses for their full-frame mirrorless cameras, but a glaring hole remained at the telephoto range of the lineup. With the introduction of the Sony FE 100-400mm f/4.5-5.6 GM, Sony has released a lens that covers a very useful focal range that can appeal to a wide range of photographers.

Wildlife photographers will be especially satisfied with the release of this lens as the 100-400mm focal length range is one of the most useful for general-purpose wildlife photography. The wide end of the range is great for close wildlife and environmental portraits while the longer end is great for mammal and large bird photography. As part of the Sony G Master lens lineup, the FE 100-400mm f/4.5-5.6 GM aims for high resolution across the entire zoom range, fast and accurate focusing along with high-quality bokeh. Complementing the small form factor of Sony’s A7 and A9 mirrorless bodies, the lens measures a compact 94x205mm and weighs just 1395g.

I obtained a copy of the lens to test out with the Sony Alpha 9 body and I have been able to put it through its paces on a wildlife photography trip to Mexico.

Build Quality and Handling

As part of Sony’s top-of-the-line G-Master series lenses, the FE 100-400mm f/4.5-5.6 GM build quality is very high. It feels confident in the hand with its robust magnesium-alloy barrel construction that is weather sealed throughout. A quick look at the back of the lens shows a rubber gasket around the bayonet mount, which ought to protect both the back element of the lens and the sensor of the camera from moisture. Sony’s own illustrations suggest that the lens barrel and switches all have seals and in theory, the lens should hold up well under inclement weather.

Unfortunately, my experience with the lens’s weather sealing is somewhat of a mixed bag. I did use the lens during a couple of light drizzles without any issues, and I believe it can withstand some rain. That said, quite significant problems arose with the Sony FE 100-400mm f/4.5-5.6 GM lens along with the Sony FE 2x Teleconverter when I used them in very high humidity conditions. When taking the camera and lens out of my hotel room, which was cool and with low humidity, into the hot and very humid outside air a significant amount of condensation built up on the lens.

Now, condensation buildup is normal and occurs with all cameras and lenses, and my Canon 1Dx and 200-400 also had condensation buildup during the same time. The issue arose when I realized that the condensation wasn’t just building up on the front element of the lens (like with my Canon 200-400 and 70-200 lenses) but on both the back element and on some of the elements inside. This startled me as I experienced no such issues with my Canon gear. The internal condensation also took unusually long to dissipate (sometimes over 30 minutes). The Sony A9 body I was using with the lens continued to function normally during this time and the problem was never seemed to affect the camera body. My experience with the quality of the weather sealing on the Sony FE 100-400mm f/4.5-5.6 GM makes me suspect that Sony’s weather sealing isn’t up to the same standard I am used too from my Canon gear which is surprising given how Sony’s own diagram clearly highlights the lens is sealed.

Overall, my experience leaves me doubting the lens’s ability to be a workhorse in challenging shooting environments. I hope to test this lens again in the future, as I have seen other reviewers claim to have experienced no such problems while testing the FE 100-400mm f/4.5-5.6 GM and I might have received a problematic copy.

The lens’s front element features a fluorine coating to help prevent dirt and fingerprints from sticking along with making it easier to wipe off dirt and fingerprints from the front element. These coatings work very well in use and make the lens-cleaning process a simple one.

Measuring 94mm in diameter, 205mm in length, and weighing 1395 grams, the FE 100-400mm f/4.5-5.6 GM is relatively compact and balances very well when used on larger mirrorless bodies such as the A9 and A7RIII. Due to their small form factor and light weight, the combination of the A9 and FE 100-400mm f/4.5-5.6 GM is incredibly well balanced in the hands and is much more maneuverable than the likes of the Canon 1Dx and Canon 100-400 lens (a combination that weighs over 1kilo more than the Sony).

Both the rotating zoom and focus rings feel very smooth. A clockwise zoom ring rotation selects the focal length. Those familiar with Canon lenses might require some mental retraining as the zoom ring rotates in the reverse direction while Nikon and Sony users should be comfortable with the zoom design. The Sony 100-400 GM’s zoom ring is smartly located towards the rear of the lens, behind the focus ring, which is ideal from a functional standpoint and a differentiator in this class of lens. All other current 100-400mm lens designs feature the zoom ring located toward the front of the lens. With the Sony lens balanced in the left palm of your hand, the fingertips are free to quickly rotate the zoom without ever inadvertently moving the focus ring due to it being in the way. This design is beneficial in ensuring that you never have any accidental adjustments of the focus while you are changing the focal length.

Situated behind the zoom ring is a useful little feature: a twistable rotary torque adjustment ring. This allows you to adjust the stiffness of the zoom ring from a setting of Smooth to Tight. When set to Smooth, the lenses zoom ring quickly twists through the entire zoom range without any stiffness which works great for when you are photographing fast action and need immediate zoom changes. Of course, with the lens set to Smooth, there is quite a bit of zoom-creep and this is mostly taken care of with the adjustment ring set to Tight. Setting to Tight doesn’t completely lock the zoom ring, but I found that this setting helps prevent lens creep. I found myself setting the adjustment ring in between Smooth and Tight for general use which offers a good balance between the two settings.

At the front of the lens is a non-rotating 77mm filter thread, surrounded by a bayonet mount for the Sony ALC-SH151 lens hood that is supplied with the lens. The push-button release allows the hood to stay locked into place and is released with ease. The interior has anti-reflective flocking which ensures maximum reflection avoidance. A fantastic addition to the hood which I would love on my Canon lens hoods is the inset sliding door that can be used to adjust polarizing filters from beneath the lens. Without this little door in place, to twist a polarizing filter you must either remove the hood or poke in your fingers from the front (an act usually leads to finger smudges all over the filter). I commend Sony for including this genuinely useful feature in the lens hood.

The lens has four switches that adorn the side of the lens barrel. The first switch is a simple AF/MF switch. Next is the focus distance limiter which prevents the lens from focusing on anything closer than 3 meters. The last pair of switches deal with the lens’s image stabilization or as Sony calls it: Optical Steady Shot. There is an On/Off switch for the steady shot should you wish to turn it off. Below that is an Optical Steady Shot mode selector, with Mode 1 as the ‘standard’ setting that stabilizes in both dimensions and is best suited for general use. Mode 2 automatically detects panning and turns off stabilization in the direction of movement. Finally, there are three AF-stop buttons situated further up the barrel at 90-degree intervals between the zoom and focus rings. These can be set by the user to operate an array of different functions via the camera menu.

Towards the back of the barrel is a collar that holds the tripod mount foot. The foot rotates smoothly, but unfortunately, there are no click-stops at the 90-degree marks for portrait and landscape positions. While the foot is well made, I’d have loved to see an Arca-Swiss style quick-release shoe built-in to complement the foot and make it easier to operate on a tripod.

Overall, the FE 100-400mm f/4.5-5.6 GM is well built, handles very well, and it has some unique features which set it apart from other 100-400mm lenses I have used. The location of the zoom ring along with the ability to adjust the smoothness of the zoom ring are excellent additions, and the inset sliding door of the hood makes using polarizing filters a cinch. The only area of concern is the less-than-ideal handling of condensation, which found its way to both the lens’s back element and internal elements when used in high humidity conditions and left me questioning the effectiveness of the weather sealing.