Sigma 150-600mm F6.3 Sport-(at 320mm your F stop is at 5.6)
Sigma 150-600mm F6.3 C (at 387mm your F stop is at 5.6)
Sigma Prime 500mm F4.5 none OS APO DG HSM
Canon 500mm is/mark2 (too expensive for me)
Tamron 150-600mm F6.3 (380mm your F stop 5.6)
Canon Prime 400mm non is (very sharp)
Canon 300mm F4 (good lens close to the 400mm)
Canon 100-400 mark 1 (don’t like the idea of dust getting in)
Canon 100-400 mark 2 (seems very good quality closer to 370mm)
So as you can see the list is large and the costs of each lens vary the sigma contemporary is the cheapest option and considered sharper than the Tamron. I think the sigma sport will be slightly better quality but it is a lot heaver and according to a lot of reviews its only a little sharper. The other lens I have been looking at is the sigma prime apo hsm dg non OS lens. It is considered to be tack sharp at f8 and at 5.6 very sharp. I am really torn between them as the sigma prime can be picked up for around £1500 second hand but it has no image stabilisation. The next sharpest would be between the sigma sport and the canon 400mm and 100-400 mark 2. The 400mm prime being a lot cheaper please see the list above what should i get? for wild life the 500mm is tempting as i have always wanted a 500mm f4 prime can not aford a canon prime.
