I want a 350mm f/4.0 OIS for ~1500 € and max 2 Kg

Coupled with the ability of using both Extended Tele Converter mode and RAW (not just JPEG), it would be a dream lens for european wildlife photographers and will probably sell well to US birders too.

• the "5" in the focal length spec isn't a typo, 300mm is too short, 400mm would be too heavy.

• same thing about the maximum aperture : f/2.8 would be too heavy (already done 30 years ago by Olympus : 4 Kg) and f/5.6 would be too slow.

• it should be (power)OIS as I don't think IBIS could cope with the amount of sway from handheld 350mm.

• 2 Kg is a hard limit : better make it lighter than that. Once you realize you need a tripod + ballhead because of the weight of the lens, the whole point is lost.

I own and regularly use a rare piece of (early)80's glass : a black Olympus OM 35Omm f/2.8. It has a nice reach and speed but it's heavy like a dead donkey : shooting handheld isn't a realistic option and it requires a sturdy tripod and a serious ballhead. After one hour or two walking with the whole setup (8 Kg), my shoulder and my back are quite sore. I really want something with the same reach while sacrifying one stop of aperture in exchange of lightness.

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Rémi