Tamron 28-75mm F/2.8 Di III RXD (model A036): Tamron’s premier with a Sony FE mount.

The Tamron 28-75mm F/2.8 Di III RXD is the first step in Tamron’s strategy to bring more lenses to the market for full-frame mirrorless cameras, such as the Sony A7R III, Sony A7 III or Sony A9. The Tamron 28-75 mm F/2.8 Di III RXD is designed for excellent image quality and beautiful background blur (bokeh). Close-up shots are also possible with this Tamron standard zoom with Sony mount, thanks to a minimum focusing distance of only 0.19m in the wide-angle setting. The usability and versatility of this new Tamron lens are enhanced by its compact size and light weight; it has a length of only 117.8 mm and a weight of 550 grams. Tamron was able to achieve this size and weight by limiting the wide-angle range to 28mm and using plastic. As far as that range is concerned, all else being equal (weight, dimensions, quality, brightness and price), then 24mm is naturally nicer than 28. But that’s not how it works. Sony makes a standard zoom with the brightness of this Tamron and a range that does go to 24mm. That zoom, the Sony 24-70 mm f/2.8 Gmaster, weighs more than twice as much, is also much bigger and costs three times as much as the Tamron. So what Tamron has accomplished with the 28-75mm is significant. The Tamron 28-75 mm F/2.8 Di III RXD offers users of the Sony E-mount system an option they have not had before. The promise of smaller and lighter lenses for mirrorless systems is also partly fulfilled.

BUILD

The design of the Tamron 28-75mm has the modern, fluid lines that are characteristic of all new Tamron lenses. The lens is slim and relatively long. The Sony Vario Tessar 24-70 mm f/4 has a zoom range that is slightly larger but is shorter. The weight of the Tamron 28-75mm is low, especially for a f/2.8 lens. That low weight is achieved with, among other things, the use of a lot of plastic. The lens does not give you the feeling that you can hammer the proverbial nail into the wall with it. However, that does not mean that the build quality is not good. The Tamron 28-75 mm F/2.8 Di III RXD is built with very small tolerances. There is no excessive play anywhere, and everything turns smoothly. The focus ring is very smooth. The zoom ring, which differently than on Sony lenses sits at the front, feels a little bit stiffer, but also turns very well. The lens has no further control elements. No AF-MF switch and no function button. The Tamron also has no image stabilization. That’s no problem when you use the lens on one of the newer cameras (see below for our test results for the image stabilization of Sony A7R II with the Tamron 28-75 f/2.8), but it’s problematic if you want to combine it with a first-generation A7. The Tamron 28-75mm F/2.8 Di III RXD has a dust and moisture-resistant construction and is fitted with a gasket on the mount. The hydrophobic Fluorine coating developed by Tamron further ensures that the front lens is highly resistant to fingerprints, moisture and dirt. The shortest focal distance is 0.19m in the 28mm setting and 0.39m in the 75mm setting, making close-up shots possible. At 28mm, you get a magnification of 1:2.9, and 1:4 at 75mm.

Sharpness of Sony A7R III shots with IBIS remains constant at 75 mm f/2.8 from 1/200 sec to 1/6 sec.

Modern Sony cameras have built-in image stabilization (“IBIS”), so that – especially for lenses with a focal length of <100mm – the need for built-in image stabilization is not so great. The sharpness of pictures taken by hand at 75 mm f/2.8 1/200 sec turned out to be the same as that of a picture at 75 mm f/2.8 1/3 sec with IBIS. That is a gain of 6 stops! In both cases, the sharpness is already less than that of a shot taken at 1/ 5-stop image stabilization gain.

IMAGE QUALITY

With the Tamron 28-75 mm F/2.8 Di III RXD, we were very curious about the image quality. Of course, we are with all lenses, but with the Tamron, we were just a bit more curious. Why? Because the Sony Vario Tessar 24-70 mm f/4, the logical competitor when it comes to a compact and affordable standard zoom, is a bit disappointing on this point. The Sony is not bad, but you do not get the maximum out of your camera with it. Especially at wide angle and full aperture, the Vario Tessar loses some points. The Tamron is another stop brighter. Great, of course, but only if the lens also performs well at full aperture, so that you can really use that beautiful f/2.8 aperture. In terms of image quality, the Tamron is indeed a step forward compared to the 24-70 mm Vario Tessar.

In the wide-angle mode, the sharpness in the center at full aperture is already excellent, the edges are good, and the corners are reasonable. Stopping down increases the quality of the edges and corners, which are at their best at f/8. The center sharpness is then slightly reduced, but the lens then achieves very good values from corner to corner. At 35mm, you see about the same pattern. At 50mm, the lens is almost flawless, with excellent scores across the entire image at every aperture. Only at 75mm does the sharpness drop somewhat at full aperture. You get that back if you stop down two stops. Chromatic aberrations are already corrected in the camera but are also minimal without those corrections. We could hardly find them in the practice shots. This also contributes to the impression of good sharpness with the lens. The lens also does not suffer much from flare with backlighting, although you do have to be careful with shots into the sun. Even with flare, the contrast usually stays reasonably good.

The Tamron has a lot of vignetting at full aperture, both at 28mm and at 75mm. But it’s reduced in the camera with the lens corrections in both RAW files and jpegs to just over a whole stop, and that’s not very much. For some photographers, vignetting is not a lens error, but part of the character of a lens. If you want it completely gone, then you can correct it in the post-processing. Although you will then of course have a chance of a little more noise in the corners. As mentioned, the Tamron uses the lens corrections in the camera. On one of our test cameras, a Sony A7R II, the distortion in jpegs was corrected, but not in the viewfinder image or the RAWs. Perhaps this is a matter of a firmware upgrade of the camera.

Autofocus

Fast AF: At 50mm, the Tamron 28-75mm F/2.8 Di III RXD focused from infinity to 1.5 meters in 0.13s.

One of the advantages of mirrorless systems is that you can easily use lenses that are actually made for other camera systems via adapters. What does not always work well is the autofocus or part of the autofocus functions. The Tamron has been specially developed for the Sony FE mount. There is therefore no problem with the use of advanced autofocus capabilities such as Eye-AF or the “Direct manual focusing system” (DMF) on Sony mirrorless cameras. It all works as it should, and at full aperture, the focus is very fast. The Tamron 28-75 mm F/2.8 has a completely new, fast and accurate Tamron AF drive system. The Tamron RXD (Rapid eXtra silent stepping Drive) focus motor is reasonably quiet. The 28-75 mm zoom is therefore suitable for video recordings with autofocus. It is not a really ideal lens for really experienced filmmakers, because the manual focus is not linear. Big changes in focus depend on how quickly you turn the focus ring. This makes it nearly impossible to create a good focus pull manually. For photography, on the other hand, it’s nice, because you can focus very accurately on a stationary subject.

Bokeh

With a brightness of f/2.8, you can use the Tamron at 75mm to blur the background. That is ideal for portrait photography. The quality of the bokeh is good. There are some “onion rings,” but not terribly much. You can, certainly at 75mm, have trouble with hard edges around the bokeh balls with really shiny subjects. If you have a busy background with a lot of glitter, that can be disturbing. But on the whole, the bokeh of the Tamron 28-75 mm F/2.8 Di III RXD looks good.

AlternatiVES

For most of the lenses on the market today, there are so many alternatives from different manufacturers that it is impossible to discuss them all. But for the Sony system, the choice is still clear. Those looking for a standard zoom for Sony E-mount cameras had three options before the release of this Tamron: the Sony 24-70 mm f/2.8 GMaster, the Sony 24-105 mm f/4 and the Sony FE Vario-Tessar 24-70 mm f/4. The first is much bigger, heavier and more expensive, but optically and mechanically also better, and the range is also bigger in the wide-angle range. So if you want the best and are willing to pay for it, then this is the lens you need. But if you don’t have that much money and still need that brightness, then the Tamron is the best alternative. The Sony 24-105 mm f/4 is also slightly bigger, heavier and more expensive than the Tamron. For that you get a bigger range on both sides and image stabilization. On the other hand, you lose a stop of brightness. The Sony Vario Tessar 24-70 mm f/4 is slightly smaller and lighter than the Tamron and now costs about the same. It offers slightly more wide-angle range. The Tamron wins in terms of image quality and brightness.

ConclusiON: Tamron 28-75mm F/2.8 Di III RXD

PROS

• Light
• Compact build
• Bright
• Fast autofocus
• Competitively priced

CONS

• No stabilization
• No switches on the lens
• Plastic body
• Zoom ring in front of focus ring