K3 iii + DA300mm


Link Posted 17/01/2023 - 09:55
Question for K3 iii users: Is the K3 iii autofocus with the DA300mm f4 (also with 1.4TC) significantly better in practice than that of the original K3? I'm thinking here of (a) time taken to acquire focus; and (b) ability to hold focus during tracking (birds, butterflies etc.). Or is the lens the limiting factor so the improved AF in the K3 iii can provide little or no benefit?

I'm sure that at one time I read about this here and elsewhere but can't find the relevant threads now.

And please don't suggest the DA150-450mm instead of the DA300mm. I know it's a superb lens but it's not what this question is about .



Link Posted 17/01/2023 - 10:55
I only had the k3 III for a short time and the af speed was much improved but not when using the older SDM lenses which I put down to the slow motor. There was a very slight improvement but nothing that would make much difference.
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Last Edited by Mike-P on 17/01/2023 - 10:56


Link Posted 17/01/2023 - 20:50
I own both the K-3 and K-3 III, and the focus speed with SDM lenses is more or less the same on both. Sometimes, what really influence the focus speed is how far off is the focus to start with. I try to "prefocus" more or less where I think my "target" will be, hoping the focus motor will start going the right way for my "target".

That said, I don't have the 300 f4 lens, but I have three SDM lenses, and all three do behave about the same.

When it comes to birds, I usually go for the 150-450. There are prefocus buttons on the lens to bring it to a focus point I set, so if I focus on something else like ground targets, I can bring it back to a focus point I've set before hand. The AF motor on this lens is also quite a bit faster than the SDM motors, but the focus throw is rather long, especially when using manual focus. On the SDM lenses, the focus ring follows the distance scale, but the focus ring on the 150-450 moves about half as far as the focus scale. However, with this lens, my "keeper" ratio is about twice as good as the 60-250. But, if somebody wants to spend a whole day birding with the 150-450, I would recommend doing some weight lifting before going. It's a big heavy lens.
Yves (another one of those crazy Canucks)


Link Posted 18/01/2023 - 12:30
Thanks, helpful . It confirms my suspicions about focus speed but I wasn't sure whether that was my imagination or I'd really read it somewhere.

Any comment on tracking with the K3 iii + DA300 i.e. once focus is achieved on a moving object does it hold focus better?

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