Tamron's suite of new lenses, however, are designed for mirrorless cameras, which invariably means that they will be much smaller and lighter. It also means that we could be seeing them not just for Canon and Nikon bodies (including the Nikon Z50, for which they would be perfect), but potentially also Sony and Fujifilm's APS-C systems as well.
Accordingly, as APS-C optics, that 18-500mm focal length actually becomes significantly more thanks to the smaller format's crop factor; on Nikon, Fujifilm and Sony it would become a 27-750mm lens in equivalent full-frame (35mm) terms, while on Canon it becomes a whopping 28.8-800mm!
The patent for the six lenses was spotted by Japanese outlet Hi Lows Note, which monitors designs filed with the Japan Patent Office. The formulas for each lens are as follows:
Optical design for the Tamron 18-500mm f/3.5-6.5 (Image credit: Tamron / JPO)
Tamron 18-100mm f/4.0-5.6
Zoom ratio: 5.610
Image height: 13.323～14.200 mm
Focal length: 18.301 43.535 102.674 mm
F number: 4.080 5.350 5.660
Half angle of view: 39.191 17.680 7.605
Lens length: 87.002 101.835 129.999 mm
Back focus: 14.503 27.315 42.000 mm
Tamron 18-200mm f/3.5-6.5
Zoom ratio: 10.443
Image height: 13.364～14.200 mm
Focal length: 18.554 55.051 193.767 mm
F number: 3.600 5.075 6.450
Half angle of view: 38.673 13.734 4.106
Lens length: 97.735 117.599 180.000 mm
Back focus: 13.815 13.815 13.815 mm
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Tamron 18-260mm f/3.5-6.5
Zoom ratio: 14.097
Image height: 14.200 mm
Focal length: 18.566 70.020 261.733 mm
F number: 3.605 5.550 6.489
Half angle of view: 37.748 10.466 3.048
Lens length: 120.000 133.768 180.000 mm
Back focus: 18.272 16.100 14.646 mm
Tamron 18-300mm f/3.5-6.5
Zoom ratio: 15.668
Image height: 14.200 mm
Focal length: 18.558 70.005 290.760 mm
F number: 3.605 5.550 6.489
Half angle of view: 38.867 10.945 2.825
Lens length: 130.000 162.903 199.994 mm
Back focus: 22.929 17.476 14.750 mm
Tamron 18-400mm f/3.5-6.5
Zoom ratio: 20.894
Image height: 14.200 mm
Focal length: 18.556 85.026 387.712 mm
F number: 3.605 5.550 6.489
Half angle of view: 38.856 9.039 2.136
Lens length: 155.243 186.883 260.000 mm
Back focus: 24.232 17.831 14.746 mm
Tamron 18-500mm f/3.5-6.5
Zoom ratio: 26.125
Image height: 14.200 mm
Focal length: 18.549 95.016 484.592 mm
F number: 3.605 5.550 6.489
Half angle of view: 38.845 8.104 1.727
Lens length: 156.884 208.996 300.000 mm
Back focus: 23.776 19.470 14.746 mm
James has 22 years experience as a journalist, serving as editor of Digital Camera World for 6 of them. He started working in the photography industry in 2014, product testing and shooting ad campaigns for Olympus, as well as clients like Aston Martin Racing, Elinchrom and L'Oréal. An Olympus, Canon and Hasselblad shooter, he has a wealth of knowledge on cameras of all makes.
