Here are the two lenses under consideration. On the left, the Tamron AF 28-75mm f/2.8. On the right, the Nikon 18-105mm f/3.5-5.6. They’re about the same size, though the Tamron weighs a few more ounces (12 v. 9.6). Considering the Nikon looks a little bulkier, where does the weight come from?
One word. Plastics. This Nikon lens is plastic and glass, where the Tamron has metal, too. Here’s a look at the docking ring of these lenses. The plastic on the Nikon lens makes it lighter… and less rugged, too. Worse, there’s an electrical connection that takes place in the ring, and for this lens, that’s the tiny spot at about 5:00 on the image below. That tiny brass spot replaces the full metal ring on the Tamron. This is known to create issues for some Nikon owners, as it produces an intermittent connectivity issue that will cause the camera to malfunction. My first lens starting having problems within a week. I exchanged it, and the second one started having problems a few weeks later. In the end, I had to send it in for repairs.
The other telling part of this is how much smaller the back element is on the Nikon lens. The Tamron lens can open up to f/2.8 (the smaller the number the bigger the shutter opening). The Nikon lens only opens to f/5.6 when it is zoomed in, which is a smaller opening, and allows 1/2 the light to pass through. What does this mean to you as a photographer?
The f/5.6 aperture on Nikon means that to get the same amount of light through the lens, the shutter has to be open twice as long. Sometimes that doesn’t matter. If you’re at the beach on a sunny day, you might want to close the aperture even more. A lot of amature photographers like to shoot at f/8 or higher. But if you’re in lower light (anything indoors, for example), you’re going to want to open your shutter up wider, and the Nikon lens can’t do it. In my experience, this means blurry shots because the camera moved a little while you took the picture, or because you’re photographing a human (tip: people move). Some of the worst pictures I ever took were indoors on Christmas morning. My subject blinked, and half the exposure was with her eye open, the other half with it closed. She looked like she had cataracts… or was a zombie. Either way, not pretty.
The Nikon lens has dropped to $329 in price, and that’s a better price than the $400 I paid. Still, if you want the longer zoom range of 18-105, and you don’t care about aperture, drop me a line here, and I’ll sell you mine for far less than that.
I’d be doing Nikon a disservice if I didn’t mention that they do have a medium range zoom that reaches f/2.8. It’s the Nikon 24-70mm f/2.8G ED AF-S. This is serious glass… you literally cannot buy a better lens… but it will cost you a little over $1,700 US. Worth every penny? Yes… if you sell your photos. Me, I give ’em away, so the Tamron is my lens for now.