Second body for wildlife photography

Looks like ISO 1600 would have given you 1/500. The new D-? should let you go there in a pinch. Go to FX and you need to add 1.4x to the lens or TC and shoot at ISO 3200. How do you gain? You need to remember that when you crop FX you're losing DR as well. A DX camera works a lot better with a 300 f2.8 than an FX camera, even for larger animals. Unless you want to get really, really close to these cuddly creatures.

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Jim