Sony's new super tele zoom lens impresses with high sharpness right at 400mm, fast focusing ability, accurate subject tracking and good use of the 66MP sensor of the A7R VI.

After nearly 10 years since introducing the first FE 100-400mm F4.5-5.6 GM OSS, Sony continues to expand its high-end telephoto lens line with the new FE 100-400mm F4.5 GM OSS version. The most noticeable differences are the fixed f/4.5 aperture throughout the zoom range, internal zoom mechanism and upgraded focus system, aimed at those who regularly shoot sports, wildlife or subjects at a distance.

In this experience, I combined the lens with the Sony A7R VI, a full-frame camera model with a sensor resolution of up to 66MP. This is an interesting duo because the high resolution of the camera body places great demands on optical quality, while AI subject recognition and tracking modes also need a lens with a fast enough focus speed to be effective.

The design is significantly larger, in exchange for flexible operation

The first thing I noticed when holding the Sony FE 100 - 400mm F4.5 GM OSS is that the size is much larger than the previous version. The lens is about 328mm long and weighs 1,840g, an increase of nearly 450g compared to the old model. When installed on the A7R VI, the entire apparatus weighs more than 2.5kg, enough to clearly feel the weight when held and operated for a long time.

However, the actual feeling of use is not as inconvenient as I initially imagined. The weight is distributed relatively reasonably, combined with the internal zoom mechanism to help stabilize the center of gravity when changing focal length. This is especially useful when shooting handheld, because users do not have to constantly adjust the way they hold the camera every time they zoom from 100mm to 400mm.

The internal zoom mechanism is also the change I appreciate most in terms of design. The entire process of changing focus takes place inside, the lens body does not extend outward like the old generation. When you need to constantly change the frame, the operation is therefore more seamless, while reducing the change of center of gravity when placing the camera on a tripod or monopod.

The zoom ring can adjust the rotation force between Smooth and Tight modes. Smooth mode makes focusing changes quicker and easier, while Tight increases resistance to limit unwanted changes. This is a small but useful detail, because with telephoto lenses, the transition from a relatively wide angle of view at 100mm to a close-up frame at 400mm often happens continuously.

Function buttons are also conveniently arranged, allowing quick operations without having to take the device down to search the menu. Sony includes a focus range limiter switch, OSS anti-shake modes, customizable focus hold button, and manual focus assist controls. The body is dust and moisture resistant, suitable for the outdoor use characteristics of this lens line.

A small detail that I appreciate on the Sony FE 100 - 400mm F4.5 GM OSS is the 40.5mm filter tray located behind the lens, near the location connecting to the camera body. Instead of having to use large 95mm diameter filters at the front, this design gives users more compact and cost-effective options, especially when needing to use ND filters to control light. The filter tray is also designed to be removed and installed separately, with a waterproof rubber seal, making it convenient to change the filter during shooting. Although working behind the lens, you still need to be careful to avoid dirt getting inside.

However, the weight is still a minus point that is hard to ignore. If you only hold the camera for a short time, it's not a problem, but when you have to move a lot or constantly hold the camera up to aim, the feeling of hand fatigue is difficult to avoid. The tripod base is also relatively large, sometimes a bit cumbersome when operating, so I think this is still a set of equipment more suitable for planned shoots and big jobs, but is difficult to carry for daily use.

Very high definition on 66MP sensor, cropped image still retains many details

Optical quality is what impressed me most when using the Sony FE 100 - 400mm F4.5 GM OSS with the A7R VI. With a 66MP sensor, limitations in the sharpness of the lens are easily revealed when enlarging the image, especially in small details or high-contrast areas.

However, Sony's new lens meets this requirement very well. Even at the largest aperture of f/4.5, the image has high sharpness, lines are clearly reproduced and there is no feeling of having to close the aperture further to achieve the desired quality. In particular, when increasing the focal length to 400mm, image quality is still maintained well, instead of clearly deteriorating like on some popular tele zoom lenses.

This is evident when viewing photos on a large screen and zooming to 100%. Small details at a distance are still clearly recorded, and areas with complex textures retain good separation. With a 66MP sensor, the amount of information captured is huge, making post-production or cropping significantly more flexible.

I especially like the A7R6's ability to switch between Full-frame and Crop-mode with just one button. At a focal length of 400mm, if the subject is still small in the frame, users can quickly zoom into the middle frame while still maintaining high enough resolution. When shooting in APS-C mode, the A7R VI still produces about 29MP images, equivalent to a 600mm focal length on full-frame.

This is the practical advantage of combining a sharp telephoto lens with a high-resolution camera body. In many situations, I may prefer to shoot a slightly wider frame to avoid cutting off the subject, then adjust the composition in post-production. Of course, cropping can't completely replace a 600mm or 800mm lens, but for a variety of shooting needs, this flexibility is well worth it.

The ability to reproduce colors and contrast is also a plus. Photos have good clarity, light and dark areas appear naturally, details are sharp but not harsh. For frames with a background far away from the subject, the long focal length combined with the f/4.5 aperture creates a clear background blur effect, helping the subject stand out more naturally.

However, bokeh is not always completely soft. With a background with many small details or interwoven bright areas, sometimes slightly clear edges can still be seen in out-of-focus areas. This is a characteristic that can be found on many telephoto zoom lenses, and in my opinion does not significantly affect the overall quality.

Another notable upgrade is that the f/4.5 aperture is maintained across the entire focal range. Compared to the previous generation, which only reached f/5.6 at 400mm, the new lens captures about 2/3 stops more light. This advantage allows the use of higher shutter speeds or reduced ISO in the same lighting conditions, which is especially useful when shooting fast-moving subjects in the early morning or late afternoon.

The good thing is that users don't have to think much about the aperture changing when zooming. Whether shooting at 100mm or 400mm, the maximum aperture remains the same, allowing for more consistent exposure control. For those who regularly use manual mode, this is a valuable improvement.

Fast focusing, combined very well with the A7R VI's AI recognition capabilities

If image quality is the optical strength, focusing ability is what makes the experience of using this lens much more pleasant. Sony says the new AF system has a maximum speed of about 3 times faster than the previous generation, and when combined with the A7R VI, the actual focus response is very fast and decisive.

During use, I often prioritize AF-C mode combined with AI subject recognition. What is easy to see is the almost instant response speed when bringing the camera towards the subject, the focus point quickly determines the correct position to monitor. When the subject changes distance, the lens also adjusts focus quickly, rarely feeling like you have to wait for the system to detect.

Compatibility with the A7R VI's recognition modes is also very good. From detecting faces and human eyes to animals, birds and vehicles, the lens responds effectively to focus information processed by the camera body. This is an important combination, because no matter how intelligent a camera body has the ability to detect, it will be difficult to take full effect if the lens responds slowly.

I most appreciate the ability to continuously track as the subject moves. Instead of having to manually adjust the AF point according to every small change, the photographer can let the camera recognize and follow the subject, thereby focusing more on the composition and timing of the shot. When the subject changes distance, the system also changes focus quickly and stably.

Of course, AI AF still has certain limitations. When the subject is too small in the frame, obscured, or located in front of a complex background, the system can sometimes misidentify it. However, the lens's response speed makes refocusing quick, reducing the risk of missing important moments.

This is also where I see the difference between a high-end telephoto lens and mainstream options. High sharpness is easy to see when viewing photos, but the ability to focus quickly and accurately is the factor that directly impacts the shooting experience. With moving subjects, being able to trust the AF system makes operations much more comfortable and proactive.

OSS optical image stabilization also helps significantly. When used at a focal length of 400mm, small hand vibrations can cause the frame to fluctuate clearly, especially when viewing through the electronic viewfinder. The anti-shake of the lens combined with the stabilization system in the A7R VI body makes images easier to observe, convenient for composition and subject tracking.

With stationary subjects, the anti-shake system also allows more flexibility when using slow shutter speeds. However, when shooting fast-moving subjects, users still need to prioritize a high enough shutter speed, because anti-shake only limits hand shake and cannot eliminate blur caused by the subject moving itself.

Another plus is the ability to focus at close distances, from 0.64m at 100mm focal length and 1.5m at 400mm. Thanks to that, the lens can also be used to capture flowers, small details in nature or subjects at close distances with beautiful background blur effects. This is an advantage that makes the 100 - 400mm focal range more flexible than specialized super telephoto lenses.

Very valuable in terms of performance, but not necessarily suitable for everyone

After experiencing the Sony FE 100 - 400mm F4.5 GM OSS with the A7R VI, I think this is one of the notable tele zoom lenses for the Sony Alpha system. The biggest strength is the balance between optical quality, focus speed and flexibility, instead of just focusing on upgrading a few individual parameters.

With a 66MP sensor, the lens still provides high sharpness, especially at 400mm focal length. Flexible image cropping capabilities, fast and accurate AF speed, and good compatibility with AI subject recognition modes help this duo effectively meet many different shooting situations.

The internal zoom design is also a valuable improvement, making operation and changing focal length more convenient. The fixed f/4.5 aperture, although not too large for a professional telephoto lens, still provides a clear advantage over the previous f/4.5 - 5.6 version, especially when needing to maintain a high shutter speed.

In return, users must accept the large size, weight of nearly 1.84kg and announced price of about 120 million VND in Vietnam. This is a significant investment, especially when Sony still has options like the old FE 100 - 400mm F4.5 - 5.6 GM OSS or FE 200 - 600mm F5.6 - 6.3 G OSS at more accessible prices.

For people who mainly photograph small birds at very long distances, the maximum focal length of 400mm may not be enough, and 600mm or 800mm lenses still have their own advantages. On the contrary, if you regularly shoot sports, wildlife at moderate distances, outdoor events or need to quickly change composition, the 100 - 400mm range is significantly more flexible.

Personally, I most appreciate the ability to combine with the A7R VI. The high-resolution sensor allows for the exploitation of a large amount of detail, while the AI ​​AF system and lens focus speed make the shooting process faster and more convenient. This is the type of upgrade where the real value lies in the image quality and the rate of capturing the desired moment, rather than just the numbers on the spec sheet. For those who want an even better focusing experience, Sony still has a "card" called A1 II - a super camera line with AI AF focusing capabilities that promises to be 2 times faster than the A7R VI.

Sony FE 100-400mm F4.5 GM OSS is clearly not the choice for the majority. However, for those who prioritize image quality, focusing performance and need a telephoto zoom lens good enough to exploit high-resolution camera bodies, this is a product worth considering, as long as you can accept its price and weight.