In this zoom simply must be borne in mind by what one is burning on the sensor. The picture corresponds to a 120-400mm with APS sensor or a 150-600mm in full format. When APS sensor differences in the BQ compared to MFT are now no longer exists. Since landing in both APS and at full frame times very quickly a few kilos in the camera bag. So a Sigma 5.0 / 6.3 with 150-500mm brings sometimes just 2 kg on the scale and costs 830. From the dimensions not to mention. Who then also finds fault with the light intensity, simply has to deal sometimes with the laws of physics. The necessary lens structures are either again significantly heavier and / or priced in a completely different league. Except and only direct competitors, the size and weight similar but more intense Panasonic 100-300. There are many comparisons with the old Oly 75-300, because you can make up his mind. What good is a large initial aperture if it does not reflect knackscharf. Since I ride in the quality of today's EPL5 or OMD would prefer the ISO value up (800). The autofocus of Oly is m. E. very quickly and accurately. Antishock at, aperture 8 and the BQ is super up to 220-230 mm. From the hand at least 1/200 (75mm) or 1/640 (300mm). Very sharp, with beautiful colors and contrasts. At 75 and 150mm, the lens is 8 m at f. E. significantly sharper and more defined than the 40-150R, which is here quite well rated. The results at 300mm are consistently described as good in my eyes. A slight weakening at the long end (more it is not) afford obviously the telephoto zoom of the famous APS manufacturers (Tests and reviews). Conclusion: If you want it even more compact when converted 600mm, eigenlich has only the following way: Super Zoomer down with a small sensor. Since I would be times the quality of the images of interest in converted 600mm; yet I found already Lumix Superzoom shots at 400mm diplomatically expressed more "borderline".
