I had a owned a Tamron 24-70 f2.8 G1 lens for two years and just traded it in on a G2 version. This post will focus on some of differences between the two lenses, so it’s not intended to be a complete review of the Tamron 24-70 f2.8 G2. More of answering the question, is it a worthwhile update, that you should consider.
Both versions have basically the same optical formula, my G1 needed about +6 AF fine tune to obtain the best images at 70mm @ f2.8. The new G2, is at 0 AF fine tune in camera. I tweaked it just a little with the Tamron docking station, mainly because I wanted to try it out. You can set AF fine tuning at four focal lengths – 24, 35, 50 and 70mm, with three distances at each focal length. I added +3 at mid distance for the 70mm end only. Tamron lets you adjust how the VC works, you can set focus limits if you need to tweak the focusing performance. It also lets you update the firmware, but currently there is only version one.
The G2 version focuses at least 50% faster compared to the G1. Just slightly slower than the Nikon 24-70 version one (which I also owned), but fast enough for most action. When I first purchased the Tamron 24-70 G1, I tested it at home in low light at home using static objects with my D700, and I didn’t have an issue with hunting. I have not tested either version in extreme low light, but specific bodies and AF settings would probably have a big impact on low light performance.
Regarding bokeh, in looking at a background image I shot of a tomato plant on the patio. I wasn’t actually testing bokeh at the time, just wanted a closer subject to shoot. I don’t really see harsh onion rings, just a smooth out of focus area. If bokeh is important in what you photograph, you may want to rent a copy and perform additional testing, but I don’t think you will be disappointed.
On VC, I can say that it’s at least a stop better compared to the G1. At 70mm with the G1 version, I still needed to be at 1/30 sec. The new G2 can get pretty consistence 70mm results at 1/15 a second. At 50mm I am getting good results at 1/8 sec with VC on, so it’s comparable to the VR on most Nikon lenses. There is stabilization in the view finder, and this can be adjusted with the dock, to bias it more toward the view finder or the subject. It’s set in the middle by default, so both the subject and the view finder benefit equally.
Handling, filter size, length and weight are all about the same. So while it isn’t a small lens, it feels fine on a FX body with a grip like the D700 or D810. The zoom ring on the G1 was ok, but the G2 zoom ring is much smoother. Overall the build quality is better, and it has weather sealing. Plus you can use the dock with it, if you do need specific fine tuning, just keep in mind that dock tuning would need to take into account any other bodies. It’s a combination of all those small improvements that I believe make it worthwhile to upgrade to the G2 version.
However, if VR / VC and AF speed are not a big deal to you, the G1 version can be very good value at something like $600 used, if you don’t already own a copy. I compared both lenses on a D700 side by side in the store for about 30 minutes, and optically they are close. In fact, I hesitated for a couple of hours, before I returned to the store and traded in my old lens on the G2.