I’ve rather lost touch with the various different formats of digital cameras these days so can anyone tell me if a Sigma 150-600mm Contemporary lens would work okay with my Nikon D3100?

D3100 is a DX format sensor (APS-C), a tad smaller than full frame, so you’ll get about a 20% increase in the focal length.

Also the body has no motor drive for the AF, you need an AF-S lens for the auto focussing to work, manual will work OK though, not sure if this lens has the contacts for the AF-S.

I am no expert, be warned…!

Thank you, that’s good info, especially re the autofocus which I hadn’t considered…