Do you need focal lengths longer than those natively available in your current Sony telephoto lens? If the lens is compatible with teleconverters, adding a 1.4x teleconverter will provide a significant focal length increase.
A 1.4x teleconverter is a small lens that mounts between a compatible lens and a camera, increasing the focal length or focal length range of the lens by a factor of 1.4x, a very noticeable amount. With a 1.4x behind it, a 70-200mm lens becomes a 98-280mm lens, a 100-400mm lens becomes a 140-560mm lens, and a 200-600mm lens becomes a 280-940mm lens. It is not hard to be impressed by those numbers.
From a functionality standpoint, teleconverters change little. With a teleconverter mounted behind it, a lens's native minimum focus distance remains the same, while the maximum magnification spec is increased by the teleconverter's magnification factor. With a teleconverter mounted, lenses continue to support OSS (Optical SteadyShot) if present, continuing to provide image stabilization functionality. Sony cameras continue to function as usual with a teleconverter installed, including providing autofocus and autoexposure support.
Shown above and below are the Sony FE 1.4x and 2x Teleconverters side-by-side.
Sony explicitly indicates which of their FE lenses are compatible with their teleconverters. With lens elements protruding from the front of the primary lens barrel, Sony and most other brand teleconverters do not fit behind a non-compatible lens. This physical limitation also prevents teleconverters from being natively stacked (without a workaround such as an adequately-long extension tube mounted between them), and it prevents a standard camera body cap from being used on the teleconverter.
The sole advantage of a teleconverter is the substantial focal length increase it provides, a benefit worth all of the disadvantages I'll share later in this review. Here is an example of the focal length increase provided by 1.4x and 2x teleconverters (Sony brand teleconverters were not used for this illustration).
The difference in framing (angle of view) is quite noticeable between the three images shown. Again, the focal length increase is the lone significant advantage provided by teleconverters.
The focal length increase numbers are very attractive, but there are costs to be paid for this feature, and this list is a bit longer than the list of advantages.
I'll bullet this list for quick reading and then will discuss the points. Here is the list of teleconverter disadvantages:
Universally true is that when magnifying the image transmitted by a lens, the aberrations are magnified and, along with the effect of six additional lens elements for light to pass through for this specific teleconverter, at least somewhat-reduced image quality is expected. Decreased sharpness (resolution and contrast) is often noticeable. While none of us want to sacrifice image quality, perhaps the biggest surprise is how minor the degradation is when using the Sony FE 1.4x Teleconverter.
Because teleconverter-compatible lenses vary in their native optical capabilities, the suitability of the results captured with teleconverters differs greatly. This site's Image Comparison Tool has with-teleconverter results for most teleconverter-compatible Sony lenses. An optically excellent lens should be selected for evaluation of the optical performance of a teleconverter. The link shared above illustrates the performance of the outstanding Sony FE 600mm f/4 GM OSS Lens with and without the 1.4x teleconverter.
The addition of the Sony FE 1.4x Teleconverter to the 600 f/4 creates a very impressive full-frame 840mm OSS lens with overall optical performance that departs little from the native lens. Only very minor sharpness (resolution and contrast) decrease and lateral CA increase is seen in the with- and without-teleconverter comparison.
The Sony FE 1.4x Teleconverter adds a modest amount of barrel distortion. Teleconverters are used to increase focal length, and that means teleconverters are most needed and most used at the longest focal lengths natively available in a lens; therefore, we only test teleconverter performance at the longest focal lengths. While increasing distortion is unwelcomed, it is not unusual for telephoto lenses to have some native pincushion distortion, especially the longest focal lengths in a zoom lens. Adding barrel distortion to pincushion distortion is equalizing, and most of our tests are showing improved overall geometry with the 1.4x in use.
Overall, the Sony FE 1.4x Teleconverter performs exceptionally well from an optical standpoint.
For most of us, the disadvantage second only to the image quality degradation is the loss of 1 stop of maximum aperture. The aperture value (f-stop) is the ratio of the focal length to the diameter of the entrance pupil. Increase the focal lengths without increasing the width of the entrance pupil, and the lens will have a narrower maximum aperture.
Fast lenses are especially advantaged when using teleconverters. An f/2.8 lens with a 1.4x mounted behind it becomes a relatively-fast f/4 lens. An f/4 lens with a 1.4x mounted behind it, such as illustrated in the 600mm image quality comparison, becomes an f/5.6 lens. An f/4.5-5.6 lens with a 1.4x mounted behind it becomes a slow f/6.3-8 lens.
Autofocus performance can be reduced with a teleconverter in use, but the with and without FE 1.4x difference is minor under reasonable light conditions. Low light levels increase the autofocus challenge, and the narrower aperture presented by the 1.4x teleconverter can increase hunting in such conditions.
Three remaining facts are that teleconverters increase the in-use size of the lens, teleconverters increase the in-use weight of the lens, and teleconverters have a cost.
I'll address the two minor facts first. The Sony FE 1.4x Teleconverter is impressively small and light, increasing the overall lens length by only 0.68" (17.3mm) and total weight by only 5.8 oz (165g). Here is the FE 1.4x mounted on the FE 600mm f/4.
Here is the FE 1.4x mounted on the Sony FE 70-200mm f/2.8 GM OSS Lens.
The mounted teleconverter shifts the lens weight forward slightly for a tiny change of balance. Zoom and focus rings also shift away from the camera body very slightly.
Sony teleconverters are expensive relative to the rest of the class. Still, the cost of Sony teleconverters is considerably less than the cost of the lens required to gain the target focal length natively (if it exists).
A single aspherical lens element is included in this lens's 6/5 (6 elements in 5 groups) design.
The Sony FE 1.4x Teleconverter features quality construction that includes weather sealing, extending the protection most compatible lenses also have. The Sony teleconverters have protective rubber around the front element to protect the teleconverter and the lens from misalignment issues while mounting.
Sony ships the 1.4x teleconverter in a very nice protectively-padded, surround-zippered, compact, rigid nylon case.
As an "FE" lens, the Sony FE 1.4x Teleconverter is compatible with all Sony E-mount cameras, including both full-frame and APS-C sensor format models. Sony provides a 1-year limited warranty.
The Sony FE 1.4x Teleconverter used for this review was purchased online/retail.
Buying a teleconverter over a longer lens for financial reasons can make sense. The very long focal length lenses are considerably more expensive than teleconverters. Using teleconverters to save space (vs. carrying a second, larger lens) when traveling or hiking can be a good decision. Utilizing a teleconverter to reach a focal length that does not exist natively is a great idea.
Sports and wildlife photographers often need longer focal lengths, and these are two of the groups most commonly utilizing teleconverters. Photojournalism, law enforcement, and many other types of photography can utilize teleconverters.
I always prefer to use a lens with my desired focal length natively available, but I often have the Sony FE 1.4x Teleconverter with me, and I use it.
The Sony FE 1.4x Teleconverter is a small and light addition to your kit, a moderate hit on your wallet, and in terms of versatility and capability increase, is a big hit to have in the gear bag.
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