Better focus with Lumix G 100-300mm Mk II

The original Lumix G 100-300mm f/4-5.6 was an affordable and basic long tele zoom lens, from the early days of Micro Four Thirds. It was generally considered a good value lens, albeit not optimally sharp in the long end, and with newer cameras, the continuous drive mode became slower in AF-C, due to a slow aperture mechanism.

Unexpectedly, since there is already the high end long tele zoom lens Leica 100-400mm, the 100-300mm lens has been upgraded to a Lumix G 100-300mm Mk II. The optical design, and, indeed, the lens body, is exactly the same, however, it gets a newer focus motor, aperture mechanism, and compatibility with newer IBIS (In Body Image Stabilization).

Lumix G 100-300mm Mk I (left) and Lumix G 100-300mm Mk II (right)

Also, it gains weather protection, with one consequence being the rubber gasket around the bayonet mount, seen to the right below:

Lumix G 100-300mm Mk I (left) and Lumix G 100-300mm Mk II (right)

I have put the lenses to the test, to see if there is any real reason to get the newer one.

Focus speed

First, the focus speed. This is a static test, with both lenses on the same camera (Lumix GX7), to see which focuses faster (Lumix G 100-300mm Mk II on the right hand side):

I triggered both cameras simultaneously using a Pixel RW-211 remote control. The video below shows the outcome of the test. First, I test them at 100mm f/4.5:

The focus delay is 0.57s for the Mk I version, and 0.55s using the Mk II version. This difference is barely worth noting, I would say they are equally fast in this test. It was done in somewhat dim indoor lightning.

In the second test at 100mm and 300mm, I test both lenses on a more modern Lumix GH5 camera:

At 100mm, the newer lens is clearly faster, with a focus delay of 0.20s (Mk II) vs 0.25s (Mk I).

At 300mm, though, I repeated the test twice with different lightning, and consistently got about about 30% slower focus with the Mk II version of the lens. This was an unexpected result. I could guess that the newer lens still has a less mature firmware, and that future firmware tweaks may improve this.

Real life use, birds in flight

One typical and challenging way to use a long tele lens, is to photograph birds in flight. This is demanding for the camera and lens, as you will typically leave the focus mode in AF-C, and trust that it gets you the bird in focus when you press the shutter fully to take the pictures.

I had the continuous drive mode enabled with the Lumix GH5 camera, and took the series of pictures under the same conditions.

I used 300mm, f/5.6, 1/640s. Note that when photographing birds in flight, you would normally use a somewhat faster shutter speed, typically around 1/1000s or more. Click for larger images:

Mk I version (focus is generally not good)	Mk II version (barring some motion blur, most are well in focus)

The first thing to note is that I get a faster framerate with the newer lens. This is due to the faster focus and aperture mechanisms. With the older lens, I'd say that the framerate drops to about half.

This is visible in the pictures above, in the sense that I get a longer stream of pictures to choose from with the newer lens. While this is certainly good, please note that the new lens still slows down the camera, meaning that the aperture mechanism of the newer lens is faster, but still not instantaneous.

As for the focus, the bird is much more consistently and accurately sharp with the newer lens. So with the same camera, and the same continuous focus mode, using the newer lens appears to nail the focus better. Again, this means a higher keeper rate.

Even if I was able to photograph birds in flight (BIF) using this combo, I'd say this is still a lot easier to achieve using a traditional DSLR system, at the same price point. So while the Lumix GH5 has taken continuous autofocus to a new level, it is still not nearly as good as a similarly priced DSLR camera, e.g., the Nikon D500.

Here are two more series:

Mk I version (1/4 in focus)	Mk II version (3/4 in focus)

Image quality

About the image quality, I have taken the same pictures using the Lumix GH5 camera at 300mm, f/5.6 and f/7.1. The full picture looks like this:

Here are 100% crops from the centre:

And 100% crops from a corner area:

I think this shows a somewhat better optical performance with Lumix G 100-300mm Mk II.

I only tested the lens at maximum extension, 300mm, since this tends to be the most challenging position for the lens, and it is also the way many will use it: At least I tend to use the lens almost exclusively at 300mm.

Conclusion

The Lumix G 100-300mm f/4-5.6 II is a nice upgrade from the first version. It adds weather protection, and the zoom ring is stiffer, meaning less zoom creep.

When using continuous autofocus on a Lumix GH5, the newer lens gives you a higher framerate, and, in my experience, better focus performance. Both are quite important for sports, birds and wildlife, which I think are key uses for a lens like this.

So, should you upgrade from your Mk I lens? If you are serious about long tele lenses, perhaps you'd rather look into the premium Leica 100-400mm.

On the other hand, the Lumix G 100-300mm f/4-5.6 II does give a real performance improvement compared with the original, and it is still smaller and lighter than the Leica 100-400mm.

While I personally wouldn't trust the weather proofing enough to take the lens outside in rain, the lens is good to bring along while travelling, as it is more likely to survive the dust, sand, and moisture issues you might encounter.