_MacTwin_ wrote: octo wrote: _MacTwin_ wrote:
The focus on the test deserves applause, but if you want to test the speed of the various lenses....the subject must be the same size on the sensor, basically report at the same magnification.
On the 300mm the tower turns out to be much smaller and finding contrast involves more time, not for nothing the times turn out to be the same with the various TCs, because as the image is enlarged finding contrast becomes easier and faster, and even if the TCs slow down...in the end the result evens out.
By itself the 300gm is the fastest ever, a missile.
Pretty sure this is an AF-C focus test, and it's not using contrast detection. It's only relying on PDAF inputs.
So basically the test is measuring the focus actuators speed.
OMG.....the AFC works using pdaf sensors,.... how do you think it
it focuses?
With contrast!!! phase detectors work on contrast..
If an object is distant and the plot small the search for contrast will be much more complex....
No, it's not using contrast: PDAF measures phase shift, not contrast levels.
CDAF is the one using contrast.
Specifically, PDAF measures phase difference of light coming from different parts of the lens. It calculates how far and in which direction the lens needs to move to achieve focus.
Mar 30, 2025 at 07:44 AM
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