A300 LiveView AF vs. OVF AF

I'm surprised there hasn't been more discussion about the fact that, in my experience, the autofocus when using LiveView on the A300 is considerably more accurate than when using the OVF. The OVF isn't bad, it's just not quite as consistent, particularly when using AF Local.

Anyone else have this experience? This would be a factor for me in considering the A200 vs. the A300. I'd also be curious how AF on the A300 compares to that of the A700: I know the A700's is more advanced on paper, but any real-world usage opinions from people who own both?

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http://www.flickr.com/photos/alwang

Perhaps I have got it wrong but doesn't the AF system work off the standard AF sensors as in the previous models ? The internal VF sensor just picks up the image in order to create the Live View.
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Keith-C

could the focus for the viewfinder be a lil out for your eye? Just a wild guess
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http://flickr.com/joenorth
a300 18-70 kit lens and 70-210 beercan

I posted this a few days back in a thread about high ISO noise, and it sparked some discussion there. Check out this post:

http://forums.dpreview.com/forums/read.asp?forum=1037&message=28157095

And the replies that followed it.

I don't have any issues with the AF in either mode - and in good light they seem equally accurate and fast. But I felt like I was getting faster and better autofocus in liveview mode compared to OVF when I was shooting in extreme low light.

I still haven't ruled out user-error - I have to try more tests with controlled conditions to rule out any other factors. But I had the same general thought as you initially - when I shoot in low light, I definitely seem to get a focus lock in AF, which is completely accurate and reliable, when I couldn't get focus in OVF mode. Now I need to find out if it's because I moved a bit and the camera found an edge or line to grab focus on while in liveview. Theoretically and based on everything I've read, there should be no differences at all between the two modes with regards to autofocus.

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Justin
galleries: http://www.pbase.com/zackiedawg

My experience is pretty much identical to yours, which is to say that in low light and using non-spot focusing (either Area AF or Local AF), LiveView often achieves correct lock where using the OVF doesn't. After thinking about this more, this is certainly puzzling, since as multiple folks have pointed out, both modes use the same AF system.

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http://www.flickr.com/photos/alwang

Exactly

Check here the design:



Light goes down to AF sensor (as all DSLR). There is no sensor on Live View. It even uses the AF sensor to mark that green circle when manual focusing.

Live-View as absolutly no influence on AF. That must be just a coincidence.

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Proud A100 and A300 dSLR owner.
Ex. s602z, with an Fuji s9500 as backup

I would suppose in LiveView mode and wide area the camera can use information form the LiveView for things like face recognition or other analysis of the object in sight.

So I guess it is not more accurate but smarter so it just goes to high contrast areas with some priority.

Obviously the focus uses same mechnism so accuracy cannot really be improved or so I believe.