All the decisions I took at the time where re-enforcing my position of moving away from wildlife photography, the A7ii in particular is a full frame sensor so would lose me any advantage of reach provided by a crop sensor. Now I do not regret my switch to Sony as I love the system, however, i recently found that when out with the camera I would still find myself getting pulled on occasion towards wildlife shots that might present themselves. In particular when on holiday in the Scottish Borders there happened to be many opportunities to photograph Red kites had I had a suitable lens to do so.
I came back from that holiday with a problem. I wanted the ability to shoot some wildlife but had to find a lens within my budget that would do the job. I also wanted the lens to double up as my telephoto landscape lens so that probably ruled out anything too big. As you can imagine this is not an easy task. The Sony E mount system does not have the lens depth from third party manufacturers that Canon and Nikon does, consequently the native lens which fit the bill, the Sony 100-400 GM retails for around two thousand five hundred pounds. At this stage I didn’t see this as an option.
After months of looking at every option available, and I mean every option (see list below)
Canon 100-400 mk1 with adaptor (slow autofocus if it worked at all)
Canon 100-400 mk2 with adaptor (as expensive as the native Sony with adaptor cost)
Tamron 150-600 with adaptor (perhaps too big for landscapes, autofocus performance?)
Sigma 150-600 with adaptor (same issues as above)
Sigma 120-400 with adaptor (contacted Sigma old lens not sure would work with adaptor)
Tamron 100-400 with adaptor (possible)
Sigma 100-400 with adaptor (possible)
As you can see I explored a number of possibilities. In the end I went with the Sigma 100-400 and sigmas own MC-11 adaptor. I think the reason I went for this over the Tamron was down to the fact that the adaptor is considerably cheaper than the equivalent metabones, and being from the same manufacturer and designed to work and be up-gradable with firmware, it gave me a little more confidence that the two would work well together.
Performance so far?
I have to say that so far the lens and adaptor combination is working a real treat on the Sony A7ii. Image quality has been fantastic which is the main issue you worry about. There are a few points I will raise which are in no way a criticism but more an understanding that with any lens there are issues you have to work around to get the best performance.