Re: Speculation on stacked BSI sensor at $4K - based on competition from Nikon/Canon
jhapeman wrote: Steve Spencer wrote: jhapeman wrote: Steve Spencer wrote: GMPhotography wrote:
Not sure we can say sensor readout makes the AF faster. That does not wash with the A7RV which has a slow sensor but an amazing AF setup. Im not real interested in a A7V myself unless it has magic dust in it like a global shutter.
Guy, sensor scan speed doesn't help focus acquisition much but it does dramatically improve AF if you are tracking over time. It is just a lot easier for the AF to keep up with the target if it can do a lot more calculations per second and sensor scan speed allows that.
Except these cameras do NOT read out the entire sensor--it only needs to read out the PDAF points and that's a relatively tiny number compared to the total sensor. How fast those can be read is a totally different thing than the speed of reading out the entire sensor. Again, you insist on that readout speed helping the AF, but that's just a leap you are making. As Guy points out the tracking on the A7RV is superb, and it's very slow in sensor readout.
Accuracy in tracking has more to do with how fast the camera can read just the AF pixels and then run the calculations on them, and then the predictive algorithms used to tell the lens where to focus next. That's why Nikon focuses on the fact that the Z6III has the Expeed 7 found in the Z8/Z9/Zf here--it's what's giving the AF improvements.
Again, you missed what I said. I said that the sensor scan speed affects the calculations per second for AF. Yes, the PDAF points are what are primarily read for AF, but a faster sensor scan speed also means greater calculations per second and those larger number of calculations per second for AF improves tracking AF and I have a Sony A9 and a Sony A7r V. The A7r V is fantastic for AF acquisition especially with its new AI module, but it doesn't track fast moving objects nearly as well as the A9 (which at this point isn't nearly as good at AF acquisition). Not surprisingly the A9 has much higher calculations per second for the AF. So, yes you are missing that when you are trying to track fast moving objects that the more calculations per second that faster sensor scan speed provides also improves tracking AF especially as you follow a target over time and it is easy to see this advantage if you have an A9 and an A7r V as I do.
Sigh. You don't get it. I have now or have had the A9, A9II, A9III, A1, A7RIII, A7RV, A7IV and A7IIIS.
The scan/readout speed for the entire sensor is totally different than the scan/readout for the PDAF system. Period.
Nobody said otherwise. You don't get it, however, that if you look at those cameras for all the data we have the sensor scan speed is correlated with the AF calculations per second. The higher the sensor scan speed the higher the AF calculations per second. If you can produce data that shows a different pattern I am happy to be proven wrong, but rumors and fake news don't count as data.
Jun 20, 2024 at 01:30 PM
Previous versions of Steve Spencer's message #16576364 « Speculation on stacked BSI sensor at $4K - based on competition from Nikon/Canon »
