Sony Ambassador Ross Hamamura pointed out this excellent video explaining the differences between how the Sony A-Mount system and E-Mount system cameras works. There are some subtle differences in the systems that change the way the cameras work, how the photographer sees images on the two devices and how the images are captured by the two different systems.
In his Facebook SonyAlphaTalk forum, Hamamura writes this…
First, I should mention that AF on MirrorLess E-Mount is very different from DSLR and even A-Mount (which is more DSLR like, in process).
IF you look inside the front of the lens on E-Mount, you will see as you change the f-stop from say f1.4 to f11 you can see the aperture close down right before your eyes (because it is showing you the exposure and DOF in Live View).
Now here is the interesting part. On A-Mount you will “not” see that same aperture close down as you change from f1.4 to f11.
It will stay wide open, but “simulate” the Exposure in Live View. Will stay wide open to AF , then close down to your selected aperture only when you shutter release (take the shot).
So, when it comes to “Low Light” AF (wide open lets in more light to help AF) , and even seeing contrast “on your target” (because of the lower DOF at wide open) A-Mount (and DSLR) seems to have an advantage with the AF process as it is on E-Mount Mirrorless currently in AF-C and AF-S/DMF with Setting effect = ON.
The video from Gary Friedman that explains the capture system differences is fantastic, and is as simple and as easy-to-follow as possible. I’ve had the pleasure of meeting Friedman in person and he’s incredibly nice and friendly and his great attitude comes across in his videos. We highly recommend subscribing to his video channel.…
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