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Why we haven't taken a stance on in-body stabilization vs OIS - and why that has changed: Digital Photography Review suggests that in-body stabilisation is better at close-up and wide angle work, whereas in-lens stabilisation is to be preferred for telephoto work.
I'd be interested to hear from long-time users of stabilised telephoto lenses on Pentax bodies with in-body stabilisation whether they prefer one system over the other, or if indeed they've noticed any difference at all.
My main reason for asking is that I'm currently using a recently acquired Pentax K-70, mostly fitted with a Sigma 150-500mm for wildlife photography, mostly birds, often handheld, and I often experience the annoyance of the photographer standing next to me in the hide, some using a very similar lens, but on an "alternative manufacturer's" body, producing sharper, clearer, more stabilised images than mine. I use in-body stabilisation "as default", but should I change over to in-lens stabilisation when I have the option?
Obviously I'll be trying to make comparisons of my own, not easy when no two subjects are exactly the same, but it would be interesting to hear from anyone else who's already made tests and come up with a conclusion.