Sony FE 2x Teleconverter Review

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 especially intrigued by the prospect of paring it with the FE 100-400mm f/4.5-5.6 GM lens and Sony Alpha 9 camera body.

Lens Specifications

1. Mount Type: Sony FE
2. Lens Elements: 8
3. Lens Groups: 5
4. Optical Conversion Factor: 2.0x
5. Light Loss: 2 f-stops
6. Compatible Formats: Sony FE Full Frame, Sony APS-C
7. Autofocus: Yes
8. Direct Drive SSM motor: Yes
9. Dimensions: 2.5×1.7 in (Diameter x Length), 63.5×42.7 mm (Diameter x Length),
10. Weight: 7.3 oz (207 g)

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 from 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.

Focus Performance and Accuracy

Because of their design, 2x teleconverters significantly inhibit a camera’s focus operation due to the loss of light reaching the autofocus sensor. When you mount the Sony FE 2x Teleconverter on a f/2.8 lens such as the Sony FE 70-200mm f/2.8 GM OSS, it slows it down to f/5.6, and when added to a f/5.6 max aperture lens such as the Sony 100-400mm GM, you are left with a f/11 max aperture. Most camera bodies won’t even autofocus with a f/11 max aperture lens, but the Sony Alpha 9 camera body maintains autofocus and subject tracking even with such a slow max aperture. For this review, I was able to test the focus performance on the Sony FE 100-400mm f/4.5-5.6 GM OSS lens. In the future, I hope to test it on the Sony FE 70-200mm f/2.8 GM OSS and recently announced Sony FE 400mm f/2.8 GM OSS.

Performance on FE 100-400mm f/4.5-5.6 GM

Contrary to my preconceptions coming into this review, the speed and accuracy of the autofocus with the FE 100-400mm GM/ FE 2x combination is relatively high.  The word “relative” is an important distinction here, with overall focus operation seeing a dramatic drop in quality as compared to the bare lens but remaining highly functional under the right conditions. This significant drop is most noticeable when trying to lock on to your subject under dim lighting conditions. In such scenarios, there just isn’t enough light reaching the sensor to achieve consistently good focus. However, when using this combination in midday light, the overall performance can be very good and honestly, it’s quite shocking given that the max aperture is a very dim f/11. The below shot of a Black Hawk catching a fish illustrates that with good light and technique, sharp photographs of relatively tricky subjects are possible with the FE 100-400mm GM/ FE 2x combo when used on the Sony Alpha 9 camera body. The hit rate in such scenarios isn’t nearly as high as with the bare lens, but the fact that you can even manage such a shot with a 2x converter on a f/5.6 max aperture zoom lens is quite astounding. When photographing fast-moving subjects such as the birds found in the photographs above, it is imperative to use the focus limiter found on the Sony lenses as it more than doubles the overall speed of the system.

Sharpness

Inevitably, adding a 2x teleconverter reduces both the sharpness and contrast of even the best lenses. The Sony FE 2x Teleconverter is no different as it is multiplying the aberrations and weaknesses of the lens it is mounted behind by a factor of 2 and there are now 8 additional lens elements for light to pass through. The image quality produced by a lens/teleconverter combination is highly dependent on the quality of the lens, with the top of the line fast aperture prime lenses usually turning in the best performance.

Sharpness and Contrast on FE 100-400mm f/4.5-5.6 GM

Adding the teleconverter to the Sony 100-400mm GM creates an impressive 200-800mm OSS Lens with an f/9-11 max aperture. As expected, overall image quality is noticeably reduced with the FE 2x Teleconverter, though the lens’ strong starting point ensures a surprisingly solid performance. Sharpness takes quite a hit, with the corners of the frame becoming somewhat mushy. Thankfully, the center of the frame remains quite usable with the sort of sharpness that reminds me of entry-level 70-300mm zoom lenses. Interestingly, sharpness doesn’t seem to improve all that much by stopping down the lens, and so there is little incentive to narrow the aperture below f/11.

Another strong point is that the loss of contrast so often associated with 2x teleconverters well controlled and the images retain a reasonable level of contrast. Lateral Chromatic Aberration increases notably with the FE 2x converter, with strong magenta and cyan popping up in high contrast areas.   I would rate the performance with the FE 2x Teleconverter as surprisingly solid and far better than I had initially expected given my past experience with f/5.6 max aperture zoom lenses used in conjunction with 2x teleconverters.

Conclusion

The Sony FE 2x Teleconverter is an important addition to Sony’s full-frame mirrorless camera lineup. It significantly extends the reach of the compatible Sony lenses for a relatively low financial cost. It is very small and lightweight and proves an excellent companion for long hikes and situations where the size and weight savings are essential. While its best to use it with fast aperture lenses such as Sony’s 70-200mm f/2.8 lens, the converter works quite nicely even with the company’s FE 100-400mm f/4.5-5.6 GM lens. There is a noticeable impact on overall sharpness and an increase in chromatic aberration, but the image quality remains quite decent. Overall, the Sony FE 2x Teleconverter is a capable performer, and I highly recommend adding it to your camera bag if you have one of the three compatible Sony lenses.