I've had this lens for 3 months, of which 3 weeks were in Indonesia, where it was thoroughly tested. I use it primarily for bird photography, for which this lens is unbeatable; the 300 - 1000mm reach at f4.5 - 5.6 is unparalleled across all systems! The size of the lens (thanks to the MFT sensor) is remarkably small, and the weight is manageable. I'm able to use the BlackRapid strap and hang the camera/lens without constantly bumping into things. I use it with the OM-1 II body; the combination produces very high IQ across the zoom range, with some drop-off with the 1.25x activated. It's clearly sturdy, and stood up to the heat, humidity, rain and mud during the recent trip. So, no regrets in plonking a portion of the nest egg!! I dinged it one star (1/2 star if possible) for some of the irritating (to me) aspects of the lens. The hood is monstrous and the hood cover is even more ridiculous (they have been safely stored in the box); it offers no protection against fine dust. I replaced it with a very sturdy and shorter Zemlin hood and got a Zemlin lens cap (very happy with these). The tripod collar has a clever (spring-loaded?) 90 deg stop, BUT this makes trying to rotate precisely to a different angle not the easiest. The knob to tighten the collar has to tightened really hard; otherwise it tends to loosen. The zoom ring, in my opinion, is too easy to turn. When carrying it on a strap on the hip, the zoom ring rotates. In summary, if you need the long reach lens, and have the means, I can't think of anything else that OM offers that even comes close!

GREAT LENS! I bought this lens in Nov. 2025 to replace my OM System 150-600mm lens. As it was very cold where I live, I didn’t get a good chance to put the lens through its paces. I also bought at the same time the OM-1 Mark II body. I got the chance to really put these items through their paces during a private photography tour in Costa Rica in Feb./March 2026. As we were photographing large and small birds at some distances, I added the TC-14 teleconverter for about 80% of my shots. Between the built in 1.25x teleconverter and the TC-14, it gave me up to 700mm (1400mm in 35mm film). The performance and shot quality were over the moon! I couldn’t believe when full out with both teleconverters I could get such great detailed shots. Even with a small subject taking up only about 20% or less of the frame at times, the cropped image had very good detail that resulted in a very good image after some editing. Coupled with the OM-1 Mark II body, the level of stabilization was super, most of what I shot was hand-held and having the added HLD-10 battery holder to balance the weight worked very well. In addition to regular shooting, I also did a lot of handheld image-stacking during the day and at night with insects and frogs – I couldn’t believe the level of stabilization doing this – not one sequence failed to stack properly and give me a great image. No other system I have ever has worked this good – even our guide was thoroughly impressed by this. Was the lens worth the money? My answer is absolutely – the image quality and weight over my previous OMDS 150-600mm lens, the quickness of focus, lighter weight coupled with internal zoom, at the easy flick of your finger to engage the 1.25x built in teleconverter, level of stabilization for hand held shooting and so much more made this the DREAM LENS. I haven’t tried it out with the TC-20 teleconverter yet but based on the performance with the 1.4x coupled with the 1.25x internal teleconverter, I’ll bet it will be great. I only found one thing I didn’t like about the lens – a minor issue but needs to be mentioned. The Lens’s padded lens cover. Not very practical on 2 points. One, it is too bulky to carry around. Two, in bird photography the guides (and the birds) don’t like the white body so most users of white bodied lenses use camouflage lens cover systems and when you have this on the hood the padded lens cover does not fit. An easy fix is to buy a 3rd party 95mm regular type of lens cap. I got a 2 piece pack from Amazon that only cost $13CDN. How about including a regular 95mm lens cap OM System!

This lens is absolutely amazing! My only regret is not purchasing it sooner. The reach, image quality, and focus speed are outstanding. It hardly ever leaves my camera now. There’s no noticeable drop in sharpness across the focal range—it's tack-sharp from 150mm to 400mm. The constant f/4.5 aperture is a real advantage, especially in changing light conditions. And if you need a little extra reach, the built-in 1.2x extender at your fingertips is an awesome feature.

This is an expensive lens, there's no doubt about it. But if you have the means to buy it, you won't regret it. It's extremely sharp, fast to focus, remarkably lightweight for its size and capability, and the handling is superb.

I regularly use this lens for sports photography and bird photography. Its so light weight and tack sharp. I love love love this lens!

Wanted this lens for quite some time and do not regret getting it. Weight to flexibility is great as I am not muscular. I have no problem carrying it around. Being a f/4.5 all the way through will allow me to use a lower ISO in dark locations. This lens will allow me to make better nature images and allow new ones.