Is the leica vario elmar sl 100 400mm f 5 6 3 long enough for birds?

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From Leica Vario-Elmar-SL 100-400mm f/5-6.3: Leica Vario-Elmar-SL 100-400mm f/5-6.3: A zoom lens by Leica for Full frame cameras, 100-400mm f/5-6.3. Leica's longest SL lens; it works with the Extender L 1.4x. Specs - Maker: Leica - Focal length: 100-400mm (zoom) - Maximum aperture: f/5-6.3 (it gets darker as you zoom in) - Made for: Full frame sensors - Mounts: L-Mount - Stabilised: yes - Autofocus: yes What it frames like - On full frame (L-Mount): as marked, 100-400mm. - ...

From Wildlife and sport: Reach: Focal length is the first thing to sort out. - Sport from the sideline and larger animals: 70-200mm to 100-400mm on full frame. - Birds: 600mm full-frame equivalent and beyond. Birds are small and far away; a common saying is that you never have enough reach for them. Smaller sensors help here. A 100-400mm lens on APS-C gives the view of about 150-600mm on full frame, and on Micro Four ...

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