In summary
The relatively light weight of Tamron’s 70-300 f/4.5-6.3 Di RXD III lens lens, coupled with its affordable price tag, will make it popular with photo enthusiasts. Support for Sony’s sophisticated focusing functions is an added bonus.
Although this lens is not stabilised, it can take advantage of the five-axis sensor-shift systems in Sony’s interchangeable-lens cameras. Up to 5.5 stops of shake correction is provided in the latest Alpha 1 camera on which this lens was tested.
Full review
Released in October 2020, the Tamron 70-300 f/4.5-6.3 Di RXD III lens (Model A047) claims to be the smallest and lightest of its type for Sony full-frame E-mount cameras. Weighing only 545 grams and only 148 mm long, it covers just over a four times zoom range from short to relatively long telephoto. Primarily designed for Sony’s ‘full frame’ cameras, it can also be used on its cropped-sensor models where it will cover the equivalent of a 105-450mm zoom range.
Angled view of the Tamron 70-300 f/4.5-6.3 Di RXD III lens without end caps and lens hood. (Source: Tamron.)
The optical design of this lens contains 15 elements in 10 groups with an LD (Low Dispersion) front element. Aberrations such as axial chromatic aberration, a common issue in telephoto lens designs, have been well corrected. The seven-bladed iris diaphragm produces a circular aperture to ensure attractive bokeh, while Tamron’s proprietary BBAR (Broad-Brand Anti-Reflection) Coating suppresses ghosting and flare.
This diagram shows the positions of the elements in the optical design. (Source: Tamron.)
Autofocusing is driven by an RXD stepping motor unit, which provides high-speed, high-precision and quiet operation and takes full advantage of in-camera features like Sony’s Fast Hybrid AF and Eye AF. Direct manual focus is supported and the lens is compatible with in-camera corrections for vignetting, chromatic aberration and distortion.
The aperture range is wide at both ends of the focal length scale as shown in the table below, shows the maximum and minimum apertures at selected focal length settings.
| Focal length | Maximum aperture | Minimum aperture |
| 70mm | f/4.5 | f/22 |
| 100mm | f/4.5 | f/22 |
| 135mm | f/5 | f/25 |
| 200mm | f/5.6 | f/29 |
| 300mm | f/6.3 | f/32 |
Because exposure levels are controlled by the camera, in all but the manual exposure mode, automatic exposure adjustments will be applied each time the focal length changes.
Who’s it For?
The 70-300mm zoom range is a popular extension to 24-70mm zooms and works well for sports and wildlife shooting, especially at longer focal lengths, where its weather-resistant construction will allow it to be used for outdoor shooting. At focal lengths between 70mm and about 105mm, it provides a natural-looking perspective for portraiture.
The apparent image compression and close-up effects characteristic of longer focal lengths can be used creatively in shots. The relatively light weight of this lens, coupled with its affordable price tag will make it popular with photo enthusiasts. Support for Sony’s sophisticated focusing functions is an added bonus.
The minimum focusing distance of 80 cm at 70mm provides a somewhat limited potential for close-up use. But at 300mm, the working distance of 1.5 metres will enable one fifth life size reproduction, which is a long way from true macro but adequate for taking close-ups of flowers and small animals.
Although this lens is not stabilised, it can take advantage of the five-axis sensor-shift systems in Sony’s interchangeable-lens cameras. Up to 5.5 stops of shake correction is provided in the latest Alpha 1 camera on which this lens was tested.
Build and Ergonomics
Most of the Tamron 70-300mm lens is made from a specially treated, high-strength aluminium-magnesium alloy, which partly accounts for its relatively light weight. This lens is the first time Tamron has used this material in the mount components of a lens for full-frame mirrorless cameras.
The smooth, low-sheen outer barrel, slim build and white lettering fit well with the design of Sony’s full frame cameras. Weather-resistant sealing is located at six points where ingress of moisture or dust is possible, as shown in the diagram below.
This diagram shows the locations of the various dust- and moisture-excluding seals in the lens. (Source: Tamron.)
The inner barrel extends by about 60 mm when it’s zoomed from 70mm to 300mm, rotating slightly as it extends. A 13 mm wide section at the front of the extension has an internal thread for 67 mm filters with an external bayonet mounting for the supplied lens hood.
The rubber-coated zoom ring begins 12 mm behind the front of the outer barrel. It’s 63 mm wide and ends in a 5 mm wide uncoated band that carries the focal length markings. Zooming is smooth, with less resistance than the 28-200mm provides and the lens has no zoom lock to prevent unwanted extension when it’s carried facing downwards.
The focusing ring 13 mm wide and is entirely ridged. It’s located aft of a 12 mm wide unridged section of the barrel that carries the lens name. This ring turns through 360 degrees when no power is available, since focusing is driven from the camera.
Behind the focusing ring is a 10 mm wide section before barrel slopes inwards to end in a solid metal mounting plate.
The lens is supplied with the HA047 cylindrical lens hood, which is made from plastic with a ribbed inner surface to minimise internal reflections. While it lacks a locking button it’s easy to fit and remove and reverses over the barrel for transport and storage.
Performance
We didn’t expect outstanding performance from the review lens, in part because of the compromises made in designing this type of lens. However, when tested on the Sony Alpha 1 camera, the review lens delivered acceptable results for an extended-range telephoto zoom.
Best of all, it was able to take advantage of the Alpha 1’s sophisticated autofocusing technologies. As a result, it could focus accurately on the eye of a Tawny Frogmouth setting on our Hills Hoist in extremely low light levels with minimal hunting. (Aan example is shown in the Samples section below). In fact, the only time hunting occurred was with subjects at the minimal focusing distance when the camera was set on focus priority.
Autofocusing was also excellent in movie mode and the camera was able to track moving subjects very accurately, even at the 300mm focal length. Some frame grabs have been included in the Samples section below as illustrations of the capacity of the lens in this respect.
Our Imatest tests were conducted with all the in-camera corrections in the Alpha 1 camera enabled. We also checked a selection of raw files captured simultaneously to identify areas that were potentially problematic.
Whereas the Tamron 28-200mm f/2.8-5.6 Di III RXD lens came close to meeting resolution expectations for the test camera’s 50-megapixel sensor with both JPEGs and converted ARW.RAW files, the 70-300mm fell further back; more so with JPEGs than with raw files.
Limited space in our test setup meant we were unable to run tests at the 300mm focal length. The longest we could manage was 260mm, where we found lower resolution than at the other focal lengths we tested.
The best results were obtained at f/5 with the 100mm focal length. Fortunately, overall performance was relatively consistent from f/4.5 to f/16. Similarly high resolutions were maintained for the 70mm, 100mm, 135mm and 200mm focal lengths up to between f/11 and f/16, where diffraction kicked in, as shown in the graph of our test results below.
Lateral chromatic aberration in JPEG files remained well within the lower portion of the ‘negligible’ band for all focal length and aperture settings and only slightly higher with raw files, showing this aberration was not an issue for this lens. (The red line marks the border between ‘negligible’ and ‘low’ CA in the graph below.)
Because both vignetting and rectilinear distortion are automatically corrected by the camera’s JPEG processing, we had to assess these potential problems by looking at uncorrected raw files. Some vignetting was visible with the maximum apertures at all focal lengths but stopping down one stop caused it to disappear.
Shots taken at 70mm were almost distortion-free but as the lens was zoomed in it transitioned to just detectable pincushion distortion at 100mm. There was a very slight increase in pincushioning as the lens was zoomed in.
We found the review lens to be fairly resistant to ghosting and flare, thanks in part to the generous lens hood and BBAR coating. But flare artefacts could be produced when a bright light was included near the edge of the frame. Flare artefacts could also be produced when shooting sun stars.
Bokeh at the widest apertures was a bit choppy, especially at shorter focal lengths. Highlight outlining was common across the zoom range and normally circular highlights took on a slight oval shape as they approached the edges of the frame at all focal length settings.
Conclusion
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SPECS
Picture angle: 34 degrees 21 minutes to 8 degrees 15 minutes
Minimum aperture: f/22-f/32
Lens construction: 15 elements in 10 groups (including 1 LD element)
Lens mounts: Sony FE
Diaphragm Blades: 7 (circular aperture)
Weather resistance: Yes, 6 rubber gaskets plus fluorine coat on front element
Focus drive: an RXD (Rapid eXtra silent stepping Drive) stepping motor, internal focusing
Stabilisation: No
Minimum focus: 80 cm at 70mm, 1.5 m at 300mm
Max. magnification ratio: 1:5.1
Filter size: 67 mm
Dimensions (Diameter x L): 77 x 148 mm
Weight: 545 grams
Standard Accessories: End caps and cylindrical lens hood
Distributor: Blonde Robot; (03) 9023 9777
TESTS
Based on JPEG files taken with the Sony Alpha 1 camera.
Based on ARW.RAW files recorded simultaneously and converted into TIFF format with Adobe Camera Raw.
SAMPLES
Vignetting at 70mm f/4.5.
Vignetting at 135mm f/5.
Vignetting at 200mm f/6.3.
Vignetting at 300mm f/6.3.
Rectilinear distortion at 70mm.
Rectilinear distortion at 135mm.
Rectilinear distortion at 200mm.
Rectilinear distortion at 300mm.
300mm focal length, ISO 12800, 1/3second at f/6.3.
Crop from the above image enlarged to show Eye AF performance. (The image noise is a result of the high ISO setting used.)
Another example of Eye AF in low light; 300mm focal length, ISO 100, 1/400 second at f/11.
300mm focal length, ISO 12800, 1/6 second at f/6.3.
Crop from the above image enlarged to 100%.
Close-up at 100mm focal length, ISO 100, 1/640 second at f/4.5.
Crop from the above image enlarged to 100%.
Close-up at 70mm focal length, ISO 160, 1/40 second at f/4.5.
Close-up at 100mm focal length; ISO 160, 1/50 second at f/4.5
Close-up at 135mm focal length, ISO 160, 1/50 second at f/5.
Close-up at 200mm focal length, ISO 160, 1/50 second at f/5.6.
Close-up at 300mm focal length, ISO 160, 1/300 second at f/6.3.
Sun stars and a flare artefact at 70mm focal length, ISO 100, 1/2000 second at f/14.
Slight veiling flare in backlit shot at 70mm focal length; ISO 100, 1/640 second at f/4.5.
Flare artefacts at 70mm, ISO 100, 1/100 second at f/11.
Choppy bokeh in close-up at 70mm focal length, ISO 100, 1/320 second at f/3.5.
165mm focal length, ISO 100, 1/320 second at f/7.1.
258mm focal length, ISO 100, 1/400 second at f/6.3.
Three frames (not directly sequential) from a 4K 50p movie clip shot with the lens at 300mm focal length showing tracking AF.
Rating
RRP: AU$999; US$549
- Build: 8.9
- Handling: 9.0
- Image quality: 8.7
- Autofocusing: 8.9
- Versatility: 8.9
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