Unusually, I have a photography-related post to make on here. After a break of 3 years, I have decided to get into bird photography. I have a 7d mk1 which is in good enough condition and ought to be up to the job, but I have no lens. I used to own a Canon 100-400 which was all right( though always seemed a bit soft at the 400mm end - maybe needed calibration or maybe just me). I'm not going to spend the best part o £2k on a mkII version but I would buy a used Mk1 again as long as it behaved at 400mm which is really the end that would probably get the most use for my purposes. However, I'm wondering if there are better options. I don't want: a Sigma 150-600 is too heavy as is the Tamron zoom of same length, so IQ aside these are out. In addition, I am unlikely to feel happy sticking a 100-400 on my Fuji unless it would be an amazing option which I suspect it wouldn't. My shortlist: Canon EF 100-400mm f4.5-5.6 L IS USM Canon EF 400mm f5.6L USM Lens Tamron 100-400mm F/4.5-6.3 Di VC USD Sigma 100-400mm f5-6.3 DG OS HSM Contemporary The Canons used or the others new are around my budget. Obviously IQ is important but so is AF speed and reliability. The 400mm is the end I'm most likely to use and weight is an issue. So what say all you knowledgeable people on here?