Far from a simply conversion of one of its existing DSLR lenses, the new Tamron 70-300mm f/4.5-6.3 Di III RXD has been engineered from the ground up for mirrorless systems – specifically the E-mount ecosystem, where Tamron hopes it will sit proudly next to the best Sony lenses.
Tamron says that the lens was "developed with the concept of bringing the joy of easy telephoto shooting to photographers everywhere." Certainly, its compact and lightweight form factor is the smallest among full-frame 70-300mm lenses for mirrorless cameras, at just 148 x 77mm and 545g (19.2 ounces).
Helpfully, it also features the same 67mm filter diameter as the rest of Tamron's family of full-frame mirrorless lenses, so you can easily swap attachments between your optics. There are now eight lenses in the Tamron Di III range for the Sony E-mount mirrorless camera lens mount.
• Read more: Tamron 28-75mm f/2.8 Di III RXD review
Model number: A057
Lens mount: Sony FE
Full frame: Yes
Image stabilization: No
Optical construction: 15 elements in 10 groups
Diaphragm: 7 blades
Filter size: 67mm
Dimensions: 148 x 77mm
Built specifically with Sony systems in mind, the lens is fully compatible with Sony's Fast Hybrid AF and highly regarded Eye AF systems, making it adaptable to all shooting subjects and scenarios. And the Tamron's RXD stepping motor drive system ensures quick, quiet, high precision autofocus performance. The Tamron 70-300mm is also weather sealed, with moisture-resistant construction, again enabling you to shoot in all manner of situations.
And of course, Tamron is also promising "superb optical performance with high image quality and aberration correction", as you would expect of the best telephoto lenses on the market.
The Tamron 70-300mm f/4.5-6.3 Di III RXD will go on sale from 29 October for an recommended retail price of $549.95 / £649.99.
Tamron's Di III range