A very interesting Tamron tidbit has appeared on Sony Alpha Rumors – an optics diagram of a patented 200-800mm f/6.7 for Sony E-mount cameras. And I’m pretty excited about the prospect and its potential to liven up the best 150-600mm lens ballpark. The rumor site has quite rightly likened it to the Canon RF 200-800mm f/6.3-9 IS USM, which my colleague, Gareth Bevan, reviewed very favorably.
Sony Alpha Rumors revealed that the patent lists the lens at 41.5cm in length, which is 10cm longer than Canon's effort. But the upside, of course, is that constant f/6.7 aperture. Let’s face it, the Canon's f/6.3 is fine in a pinch but most photographers would want a much wider aperture at 200mm, so losing less than 1/3 of a stop – in my opinion – is much of a muchness. But at the telephoto end, the difference between f/6.3 and f/9 is roughly a whole stop. Now that does make a difference.
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