Yes, it's a coherent solution for hand-held animal photography on your DC-G9. This lens is Micro Four Thirds mount, compatible with the Micro Four Thirds sensor, and features autofocus as well as optical stabilisation, with a focal length of 100 to 300mm.
Compared with your 45-150, you gain a lot in range: 300 mm corresponds to around 600 mm in full-frame equivalent on Micro Four Thirds, which is much better suited to distant subjects such as animals.
Points to bear in mind :
- It's heavier, at 520g, so a little less compact to hold hand-held for long periods.
- Its f/4-5.6 aperture is less bright at the zoom end, so you need good light or a higher sensitivity.
- Several sources present it as a telephoto zoom suitable for wildlife and distant subjects.
If you're looking for more magnification without changing your system, it may be just what you're looking for.
I am very satisfied with the combination. The image stabilisation of the lens does not work in combination with the stabilisation of the camera (so you have to choose one or the other and then body is preferable in my opinion), but this is not a disadvantage compared to the Olympus 75-300 of the same price. The lens is relatively light, so I always carry it in my backpack. Despite the plastic tubes, it is robustly built. At long focal lengths, the focusing is rather slow, so for sports photography you would probably have to go for a professional lens...
I bought the 100-300 in addition to the 14-140 that came with my GX8. This covered the whole range of focal lengths. The 100-300 is good for my intended use with the compromise of investment and performance. the 100-400 would be better but 3x more expensive. in this case already have a 14-42 I would opt for the 45-200. Consider if brightness is an important criterion. for "general public" wildlife photography one chooses good weather, backlighting and sound effects for the pros who choose the more powerful 100-400 versions or even more. for a very reasonable price of about 350, the 45-200 will be a good "passe-partout".
I use this lens with the G81. It's compact and delivers sharp images. Handheld, I would shoot from 200 onwards either with a tripod or multiple shots; this is the more common option for me🤗.