Released in 2016 alongside the Sony FE 70-200mm f/2.8 GM OSS and Sony FE 1.4x Teleconverter, the Sony FE 2x Teleconverter is an essential addition to Sony’s full-frame E-mount lineup. Given the relative lack of dedicated telephoto options available to the mount, the Sony FE 2x Teleconverter dramatically enhances the versatility of the lenses it is compatible with: the Sony FE 70-200mm f/2.8 GM OSS, the Sony FE 100-400mm f/4.5-5.6 GM OSS, and the recently released Sony 400mm f/2.8 GM OSS. The teleconverter maintains full communication between the lens and the E-mount mirrorless camera body it’s mounted on, which ensures the proper function of the camera’s exposure metering, autofocus, and image stabilization. The 8-element / 5-group optical design includes one Aspherical Element to minimize chromatic aberration while maximizing resolution.
Additionally, Sony claims the lens is dustproof and moisture-resistant, which means it should continue working well when used in inclement weather conditions. However, the dramatic teleconverter effect comes with some distinct penalties, including a loss of 2 stops of brightness compared to your lens’s usual maximum aperture, along with a reduction in overall image quality.
While all 2x teleconverters degrade the quality of an image, some are better made than others, with the high-performing Canon’s EF 2x III Teleconverter coming to mind. I was keen to see if the Sony FE 2x could perform at the same high level and was especially intrigued by the prospect of pairing it with the FE 100-400mm f/4.5-5.6 GM lens and Sony Alpha 9 camera body.
Build Quality and Handling
Like the rest of Sony’s GM lens lineup, the Sony FE 2x Teleconverter is well-built with a magnesium-alloy barrel and metal lens mount. You might think that the teleconverter would be relatively hefty given the optical design which features 8 elements including one aspherical element, but it’s incredibly light at only 207 grams. It is also quite diminutive in size being just 62.4 x 42.7 mm. The small size is very appealing and aids in maintaining the relatively small form factor of the system. Sony claims the converter is dustproof and moisture resistant which should allow the lens to continue working as intended in inclement weather conditions. It shares this dust and moisture-resistant design with the Sony 100-400mm f/4.5-5.6 GM lens and the Sony Alpha 9 camera. My experience in the field with the Sony Alpha 9 camera, Sony 100-400mm GM lens, and the FE 2x Teleconverter left me with some questions regarding the weather sealing’s reliability, especially when it comes to handling high humidity.
In my review of the Sony 100-400mm GM lens, I stated that the moisture resistance of the Sony lens is not up to the same standard as that found in my Canon EF 200-400mm F/4L and Canon EF 70-200mm f/2.8L lenses. A few of our keen readers pointed out that this might not be such a fair comparison. After all, the Sony lens, which extends in and out as one changes its focal length and thus “breathes,” could never hope to be as resilient to the air outside as the Canon lenses I compared it to that employ an internal zoom design which doesn’t allow any air from the outside to enter internally. Unfortunately, the same explanation doesn’t work with the Sony FE 2x Teleconverter which experienced internal condensation buildup on both the front and back elements when mounted on the Sony 100-400mm GM lens.
I encountered this on two occasions. It first occurred 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 and teleconverter. The same thing had occurred two days earlier when I used the Sony 100-40mm GM without any teleconverters. Now, condensation buildup is normal and occurs with all cameras and lenses, and my Canon 1Dx and 200-400, and 70-200 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, including when I mounted Canon’s second generation and non-weather sealed EF 1.4x Teleconverter onto my Canon lenses. The internal condensation also took unusually long to dissipate (sometimes over 30 minutes).
The second time that condensation found its way onto the back element of the teleconverter/lens combo was during a heavy rain shower that caught us by surprise while our boat was in the mangroves. Due to the heavy rain, I placed all my lenses and cameras in a nylon bag to protect them. The downpour only lasted for five minutes, as is common on the coastline in the Yucatan. While in the sealed bags, the high humidity created an environment where condensation formed on the front elements of all the lenses. Again, the Sony lens and teleconverter picked up internal moisture while my Canon gear, including Canon’s older generation x1.4 teleconverter, exhibited no such issues.
There is a case to be made that I am expecting too much of a lens without an internal focus design that isn’t in the same price range as the Canon 200-400 lens. Nonetheless, the incidence of condensation on the front and back elements of the Sony FE 2x Teleconverter is cause for concern. For many users, this won’t matter in the least, and it’s certainly rare to use your camera in such humid environments. For users like myself, who spend a bulk of their time in the tropics where high humidity is a daily struggle, it’s essential that the lens and matching teleconverters exhibit a greater resilience to internal moisture buildup than what I experienced with the Sony 100-400mm GM lens and FE 2x Teleconverter.
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