Sony FE 600mm F4 GM OSS Review - Test

In nature photography, especially when capturing shy and wild animals, the use of telephoto lenses with focal lengths of 500mm or more is often necessary. Additionally, since many animals are active during the early morning or late evening, these lenses should also be as light-sensitive (fast) as possible. As a result, nearly all major camera manufacturers offer 600mm lenses with a maximum aperture of f/4.0.
After working extensively with Canon and Nikon systems, I'm currently exploring the Sony system. I've had the opportunity to thoroughly test the Sony FE 600mm F4 GM OSS lens, particularly with my Sony A6700. I will share about how it performed on my camera in this review. But first, let's delve into the technical specifications of the lens, which can also be found on a specific website.


Specifications of the Sony FE 600mm F4 GM OSS

The Sony FE 600mm F4 GM OSS is a prime lens with a fixed focal length of 600 millimeters and a maximum aperture of f/4, with a minimum aperture of f/22. It comprises 24 lens elements arranged into 18 groups, including a filter lens. The aperture consists of 11 aperture blades designed to produce pleasing bokeh. The lens has a minimum focusing distance of 4.5 meters, achieving a maximum magnification ratio of 1:7.14. Additionally, it features optical image stabilization and is compatible with both the 1.4x and 2x teleconverters from Sony.
The Sony FE 600 F4 GM OSS is equipped with several control features, such as switches for optical image stabilization, focus mode, Full-time DMF ON/OFF, focus range limiter, and four customizable focus hold buttons.
In terms of dimensions, the lens measures 163.6 x 449 mm and weighs 3040 grams.


AF Performance of the Sony FE 600mm F4 GM OSS

When used in combination with the Sony A6700 and A6400, the autofocus of the Sony FE 600mm F4 GM OSS operates extremely quickly and with precision. The subject recognition on the A6700 also responds rapidly and works nearly flawlessly, even with birds. This remarkable performance is not solely attributable to the camera but is also influenced by the lens. This becomes apparent when comparing it to a Sigma 150-600 Sports lens instead of Sony's 600mm. With the Sigma lens, the autofocus is noticeably slower, and subject recognition is less responsive. While photographing birds from a fixed position, I frequently switched between the Sigma and the Sony 600mm F4. The Sony 600mm performs significantly better in bird eye recognition. A bright super-telephoto lens not only improves autofocus speed but also appears to help the camera identify subjects more easily. I can't precisely determine the reasons behind this, but the difference is clearly noticeable.

The autofocus of the Sony FE 600mm F4 GM OSS, when paired with the Sony A6700, is highly accurate. In this instance, the subject recognition immediately identified the robin, and the focus was precisely set on its eye. The rate of correctly focused images is exceptionally high, and in a direct comparison to my R5 and the EF 600mm F4, Sony's hit rate is noticeably higher.

The subject tracking, such as when capturing flying birds, worked without problems with the A6700 and FE 600 combination. The autofocus system rarely had any issues, even when tracking fast-flying birds, whether they were approaching the photographer or moving parallel to the photographer.


Image quality of the Sony FE 600mm F4 GM OSS

The Sony FE 600mm F4 GM OSS produces very sharp images with natural and neutral color reproduction and great contrast. To compare it with the Canon EF 600mm F4 L IS USM (II), I used a Sigma MC-11 adapter to adapt the Canon lens to the Sony A6700. Both lenses showed similar contrast and sharpness characteristics. However, the Canon lens appears to resolve slightly more details, although this difference is practically negligible.

The Sony FE 600mm lens provides rich, high-contrast images with excellent sharpness. It is capable of resolving even the finest details in feathers. Furthermore, when paired with the A6700, the autofocus (AF) system is exceptionally accurate, ensuring precise focus.

Even with the 1.4x teleconverter, the image quality of the 600mm lens remains at a very high level, and only with the 2x teleconverter you can notice minor reductions in resolution. However, stopping down the aperture slightly can compensate for these reductions. On a day when test shots were taken with the Sony 600mm lens, I also worked with the Sigma 150-600mm lens, to compare both lenses in terms of image quality. It became evident that 600mm may not necessarily be 600mm when focusing at close distances. The Sigma 150-600mm lens, for instance, behaves more like a 500mm lens in close-range situations rather than the specified 600mm. This is a significant practical difference. Therefore, choosing a fast prime lens not only rewards you with significantly improved image quality and a better autofocus system but also provides you with "true" 600mm focal length in close-range situations, instead of often substantially less.

The specified focal length of 600mm is not always equivalent to true 600mm focal length, especially when using zoom lenses. The images show a comparison between two lenses: the Sigma 150-600mm and the Sony 600mm F4, both set to 600mm focal length and using the same camera settings and distance to the subject. The Sigma lens, in this instance, provides an actual focal length of just about 500mm, if it is used at the close focusing distance. In contrast, the Sony 600mm lens indeed delivers the full 600mm focal length. Additionally, it mentions that the bokeh, or the quality of the out-of-focus areas, is significantly more pleasant with the Sony prime lens, even when using the same aperture setting.

So the high price of fast prime lenses is indeed justified. While telephoto zoom lenses are popular and versatile, prime lenses offer even better performance in every aspect, except for zooming. When it comes to extending the focal length using teleconverters, this works in most cases only with prime lenses and there are only a few zooms working in combination with an extender.


Built quality and handling of the Sony FE 600mm F4 GM OSS

The Sony FE 600mm F4 GM OSS lens is crafted with exceptional quality. It features a smoothly operating focus ring along with various other control options, such as switches for the image stabilizer, focus limits, and customizable focus hold buttons. With a weight of 3040g, it is, to the best of my knowledge, the lightest 600mm telephoto lens with an aperture of f/4 and can be used handheld without any issues. Additionally, even though I've never personally used filters on my large telephoto lenses, this 600mm lens offers the option to use 40.5mm drop-in filters.


Conclusion

The Sony FE 600mm F4 GM OSS is a professional super-telephoto lens with a focal length of 600 millimeters. It delivers very sharp images with an appealing bokeh and great contrast. Even when used in combination with teleconverters, the image quality remains at a very high level. The ultra-fast autofocus is extremely precise. With a weight of only 3040g, the lens is also suitable for handheld use. So, for those who need great image quality and a fast and reliable autofocus , the FE 600 GM OSS is an excellent choice. Highly recommended.