I was very interested in this portrait zoom lens. I spoke to a Tamron representative as I couldn't find detailed specs anywhere on the internet. Speaking to a Tamron rep, she mounted a 35-150mm lens on a Canon 5Div body and checked focal lengths in Aperture Priority AV to find the widest aperture at each focal length. Here's what we found: 35-49mm f2.850-84mm f3.285-104mm f3.5105-150mm f4
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