I chose these bowls because they have some finer details at high magnification. Here’s the Tamron version:
Cropped to the same size and proportions, here is the Nikon version:
Even without magnifying these images to show full resolution, you can look at the edge of the bowl and see that the top image is sharper than the bottom. When you look at the background, the bottom image is sharper. The question is… what do you want to be in focus?
I focused on the front edge. That’s the subject in this photo, so I want that to be tack sharp (photographer slang for really well focused). Unfortunately, it’s not that sharp in the Nikon version. Why? It’s all about the aperture.
Both images were taken in aperture priority, and I opened it as wide as I could. For the Tamron image, that was f/2.8. The wider opening meant the shutter was only open 1/40th of a second. The Nikon image below could only be opened to f/5.6, and the camera kept the shutter open much longer, 1/10th of a second. Even though my subject wasn’t moving, the length of time the shutter was open meant a little blur in the image. Yes, the Nikon has image stabilization, but because the shutter speed was faster in the Tamron image, the picture is sharper.
The other thing a wider aperture does is it blurs the background. In the top image, the background is “blown out” because of the larger aperture. In the bottom, the narrow aperture keeps the stripes of the bowl in greater focus.
The thing I like about the Tamron lens is I can set it to f/5.6 if I want to (sometimes you want the background to be more focused), but with the Nikon lens, you don’t get a choice. There is no f/2.8, so you don’t get a choice.