Sigma 150-600 Custom Settings for Birding

Frank, that certainly sounds like a problem, no question.

fyi my post above was directed towards Canonuser123, as his concern sounds just like mine (and many others on the forum) when we first got this lens.

Perfectly Frank wrote in post #18623140
I have not used my C version in awhile. Last weekend I took it to an air show and it was slow at acquiring focus. I missed several shots because of that.
While at the show I talked to photographer who had the Tamron G2. We discussed focusing speed, and he said his G2 was very fast. So now I'm thinking
of buying the G2. The stabilization in my Sigma C fails intermittently. I have to find the lens receipt and see if it's still under warranty.

Besides focusing speed, do you have an opinion on IQ between the Sigma C and your TG2 ?

I was able to get some pretty decent shots with the C and could probably have done better given time to acclimate better.

Certainly not trying to influence you, just sharing my experience. The G2 is a really nice piece. It's really not a fair comparison because it's a much newer model than the C. The G2 has been quite fast & sharp on my bodies, but most importantly... it produces on the wife's 80D, in her hands!

I still have the C, because I sometimes like to be able to carry something light and have the ability to go fairly long if I need to.

If you do send it in, please share the results. If it helps, I'll send mine in too.

Perfectly Frank wrote in post #18623303
The problem with my lens is this...with OS on and panning, the image in the VF will jerk about violently, and a noise or clicking sound will
come from within the lens. Any images taken at this point will be blurred. This will last for a few to perhaps dozens of frames. Then the fault
will clear for awhile but return later. Kind of a random thing. Turning off OS returns the lens to normal.

A trip to Sigma is in order.

I had that same problem with a Canon 70-300 USM IS lens, it was very random but annoying.

CyberDyneSystems wrote in post #18623256
This was one of the main discussion points when the lens first came out. The OS does not show what it is doing in the same way that the Canon lenses do. I think one of the dock settings that we all ended up using helped this. In either case, the OS did work, you just could not see it's effect as readily in the viewfinder.

I just decided that unless I am panning that I will keep the shutter speed up, the image stabilization may be working but I just don’t trust it. I still think it is an incredible value for a 600mm lens.

I set up C1 with the dynamic auto focus., then set up C2 with dynamic auto focus and the more aggressive stabilization setting. I find I use C1 almost exclusively.