Tamron 70-300mm f/4.5-6.3 Di III RXD Review

Focusing

The Tamron 70-300mm f/4.5-6.3 focuses very accurately and pretty quickly. It is not quite as fast to focus side-by-side against native Nikon lenses that I tested – including consumer lenses like the Z 24-200mm f/4-6.3. Even so, its focusing speed is hardly slow. I could really only tell the difference side-by-side.

As for focusing accuracy, the Tamron 70-300mm f/4.5-6.3 struck me as being on the same level as a native Nikon Z lens. Accuracy was almost perfect in every case. This has a lot to do with the camera body as well as the lens, however. Considering that there are several dozen Nikon and Sony cameras which are compatible with this lens, it’s worth testing the focusing accuracy on your particular camera before relying on it in critical situations.

Finally, the close-focusing capabilities of this lens are fine but nothing remarkable. With a maximum magnification of 1:5, you can fill the frame with something that’s about 7.2 inches wide (if you’re using a full-frame camera). That’s assuming you’re at 300mm. At wider focal lengths, the maximum magnification is significantly worse, with less than 1:9 magnification at 70mm. The end result is that this lens is not a great choice for close-up photography, even though it’s usable in a pinch.

Distortion

The Tamron 70-300mm f/4.5-6.3 has relatively high levels of distortion for a telephoto lens, aside from its distortion-free performance at 70mm. As you can see in the graph below, there is noticeable pincushion distortion at the longer focal lengths:

When I say “noticeable,” I’m referring to a lab environment. In the field, telephoto lenses are less likely to be used for subjects with lots of straight lines in the first place, such as architectural photography. So, you may never see this distortion at all – even without the distortion profile available in most post-processing software.

A maximum distortion of 3.14% pincushion isn’t terrible, but most telephoto lenses have low distortion in the lab, and this is higher than I had expected. Here’s a simulation of 3.14% distortion to put this measurement into context:

Vignetting

Telephoto lenses in general tend to have less vignetting than their wide-angle counterparts, but the Tamron 70-300mm f/4.5-6.3 has some room for improvement here. With a maximum of 1.72 stops of vignetting (found at infinity focus and 70mm), it’s pretty easy to correct the vignetting on this lens, but you will notice it in uncorrected photos. Here’s a full chart of the lens’s vignetting performance:

Personally, I consider anything under about 1 stop of vignetting to be negligible, while anything under 1.5 stops is not going to need correction in a lot of photos. By those standards, the Tamron 70-300mm f/4.5-6.3 has excellent vignetting performance by f/8. But I would have liked to see a bit less vignetting wide open.

Lateral Chromatic Aberration

The Tamron 70-300mm f/4.5-6.3 Di III RXD has an interesting chromatic aberration profile. At the wider focal lengths, it has no visible CA. Even at 200mm, the levels are quite low. However, at the longest focal length of 300mm, chromatic aberration levels jump up significantly.

Here are the measurements I recorded in the lab:

In general, values under 1 pixel of lateral CA will not be visible in real-world photos, even uncorrected. Chromatic aberration is also relatively easy to correct in post-processing with minimal artifacts. This lens has excellent CA performance at the wider focal lengths, but at 300mm, it leaves something to be desired.

Bokeh

As a telephoto lens, the Tamron 70-300mm f/4.5-6.3 will often give you out-of-focus backgrounds despite the lens’s narrow maximum aperture. But that’s different from the concept of “pleasant bokeh,” meaning out-of-focus areas that are aesthetically pleasing.

Bokeh is subjective. Personally, I like the Tamron 70-300mm’s background blur in most of my photos, but it isn’t perfect. Specular highlights sometimes take on an edge with this lens, and there’s a bit of longitudinal chromatic aberration (color fringing in out-of-focus regions). You’ll also notice a “cat’s eye” appearance in the corners of the frame – not something that bothers me, but some photographers don’t like that look.

The photo below is a stress test for bokeh due to all the specular highlights. You be the judge.

Sharpness

Often, consumer telephoto zooms like this one will be sharper at the wider focal lengths and gradually become less sharp as you zoom in. However, the situation with the Tamron 70-300mm f/4.5-6.3 is more complex than that.

First, let’s look at the 70mm performance:

Although there are certainly sharper lenses, this is a solid performance at 70mm. I have no complaints about the central sharpness at all, which reaches its highest marks wide open at f/4.5 and stopped down slightly to f/5.6. Midframe performance is a step down, but still good. Corner sharpness at 70mm isn’t bad, but it never gets as sharp as I’d like, even when stopping down to f/8.

Now 100mm:

The performance at 100mm is really interesting. In the center, sharpness levels are quite high – actually, it’s the lens’s sharpest focal length for central performance. Unfortunately, the corners never hit their stride regardless of the aperture. In terms of corner sharpness, 100mm is the weakest focal length. It’s still usable, but not great, and stopping down doesn’t help much.

Next is 200mm:

At 200mm, the center is weaker than it was before, but the corners are stronger. Midframe sharpness has stayed about the same. In my opinion, that’s a good tradeoff for something like landscape photography, where you’ll usually want consistent sharpness across the frame. The sharpest apertures at 200mm are f/5.6 and f/8, but f/11 isn’t far behind.

Finally, here’s 300mm:

The 300mm performance is very similar to what we saw at 200mm, although a hair weaker. The consistent sharpness from the center to the corners again makes it a compelling choice for landscape photography. This time, the best apertures are f/8 and f/11.

Overall, I deem the Tamron 70-300mm f/4.5-6.3 to be a reasonably sharp lens. For a $550 / $700 third-party zoom, it exceeded my expectations. The lens’s weakest area is corner sharpness around the 100mm mark, which is not as high as I’d like for making large prints. Otherwise, there isn’t much to complain about.

To get a sense of the Tamron’s real-world sharpness, you can download full-resolution raw files in our official Tamron 70-300mm f/4.5-6.3 sample gallery.

On the next page of this review, I’ve compared the Tamron 70-300mm f/4.5-6.3 Di III RXD head-to-head against other lenses that you may be considering. So, click the menu below to go to “Lens Comparisons.”