AP was the first UK outlet to get hands-on with Tamron’s new superzoom, which covers an astonishing zoom range and benefits from a light and compact form factor. Michael Topham tests the first working sample
Tamron 18-400mm f/3.5-6.3 Di II VC HLD review: Resolution, shading and curvilinear distortion
Our Image Engineering Tests tell us the lens is at its sharpest when it’s used at the wide end of the zoom and gets progressively less sharp as you zoom in. For the sharpest results at 18mm you’ll want to use the lens around f/5.6, whereas at 70mm you’ll want to close down to f/8 to see an improvement in corner sharpness. The level of sharpness drops off quite noticeably when you push towards 400mm, with diffraction visibly softening images throughout the focal range from f/16 onwards.
Use the lens at any point in its zoom range at its maximum aperture setting and you’ll notice the corners appear darker than the centre. Vignetting is at its strongest at 18mm, but improves considerably by stopping the lens down a few stops to f/8. Corner shading is less of a concern at around 70mm, but gets more obvious again at longer telephoto lengths. Stop the lens down from f/6.3 to f/11 at 400mm and the light fall off towards the corners subsides.
At 18mm, the lens displays strong signs of barrel distortion, whereby straight lines towards the edge of the frame bow outwards. The amount of barrel distortion subsides as you begin to extend the zoom; however you’ll find it very quickly turns to pincushion distortion. Users will find they’re able to correct distortion by applying lens profile corrections, however at the time of testing a lens profile wasn’t available.