Sony where are your fast zoom lenses?

Started Jan 29, 2014 | Discussions thread
kaiser soze Regular Member • Posts: 223
Re: This doesn't add up

Mike Fewster wrote:

You are right about the af being slower. That's because all mirrorless cameras have to use cdaf rather than pdaf to do the autofocussing (it's the same for all brands). That is why Sony invented the slt range of mirrorless cameras so they could use the fast pdaf focussing. On the other hand, all pdaf cameras (of all brands) are prone to need calibration to remove the built in errors that pdaf can give. Which is why almost all (certainly all the more expensive) dslr cameras of all brands have microfocus adjustment. cdaf cameras (of all brands) can't have this error.

Recently a new wave of mirrorless cameras have emerged that have sacrificed some of the pixels on the sensor to get faster focussing. Some, but not all, Sony models now have this but the Sony af speeds aren't as good as some of the others now available. pdaf cameras are still the fastest. You can get pdaf on the Sony interchangeable lens compact cameras (the Nex series) by using Sony a mount lenses and a special adapter- The Sony Nex cameras are unique in having this adapter which allows pdaf focussing however the price for this is an expensive, largish, adapter and larger lenses
Mike Fewster
Adelaide Australia

Mike, thanks for this clear statement. I will add several things. First, the actual advantage in focusing speed is not absolute, and even though SOME mirrorless cameras focus more slowly than SOME dslrs, the difference that is real is likely not huge and only matter in very specific situations. On top of that, AF is not a panacea. No camera knows what I want to focus on, or how much depth-of-field I want. There are lots of camera enthusiasts nowadays who have never even used a camera that didn't have AF, and who never learned how to focus a camera. It is now wonder then that they have no appreciation for the very useful manual focusing aids that you get with the likes of the NEX-7, which would not work without the electronic viewfinder. If I were considering a camera with a mirror, I would most likely get one of the better SLT cameras. You get the PDAF, plus the manual focusing aids, which gives you the best of both worlds, and you only lose 1/3 stop, which isn't much at all, and for someone who wants a bigger camera and bigger lens, you can make up for the 1/3 stop loss by using a faster lens.

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