A-99 and understanding the auto focus ?

Started Dec 29, 2012 | Discussions thread
3sgilbert Senior Member • Posts: 1,349
Re: Yes, Rich has found it...

copejorg1 wrote:

JusLookN wrote:

Hopefully this works as you mention. But on the Nikon it is different; which is where Trevor used it. On older Sony cams, this button (AF/MF) toggled(or locked; depending on which mode you selected) the auto-focus. In the Nikon system this button focuses as does a half press of the shutter and releases when you release the button. Even in continuous mode, on the Nikon ,this button only focuses when pressed. This feature is used in Sports shooting by many Nikon and Canon shooters, as they prefer to activate focus on the intended subject when they press that button; then press the shutter. The focus tracking is only activated when that button is pressed. It can also be programmed(D-300) where it tracks with half press of the shutter button as with the Sony, also. It's just that the continuous focusing on the Nikon is activated with this action whereas the Sony is locked; so to speak. As I mentioned earlier, I don't have the A-99, so I'm not saying you are wrong! And if I didn't get it right, I apologize!

Note: Tracking is the key word here!

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I'm kinda partial to video, but I'm hangin!


Your explanation is an accurate description of the Minolta/Sony SLR and SLT models previous to the A99 that had/have the rear AF/MF button. However, the A99 does have the "AF-On" functionality added as a new feature, so it can be used the same way that Canon/Nikon users have gotten used to over many years (i.e., "Back Button AF" in combination with continuous AF).

Some of us here on this forum had lobbied for that feature (along with auto ISO in Manual, etc) for quite some time, so it's good to see Sony finally implementing some of those features.


Yep, be great if the provided af-on via firmware for their flagship apsc. The inclusion of it in the a99 directly indicates they know we want it surely the a77 would benefit even more than the portrait landscape model. I too lobbied for auto iso but I would prefer the newer nikon implementation with an iso range, minimum shutter speed, and adjustable bias. That said im glad to have the iso range adjustment just wish it was in 3rd stops...

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