James Silverton wrote:

lid wrote on Tue, 09 Sep 2008 08:25:12 -0500:

DudeBoyz wrote:
In look at my camera, I see these four Auto-Focus modes available:

- Face Detect
- iESP
- SPOT
- AREA

I was wondering if the preference for SPOT on my part is
heavily in the minority, or if other folks still prefer to
not give up the farm and go fully-auto.

I have the Canon 30D, and use center spot. This is really
center-area ... it is three times bigger than the marked
square, and the area is much too big.

Before I got this, my first auto-focus camera, I had always
wondered how well autofocus could work for general scenes.
Sure, if it all is at infinity, or is flat, perpendicular
to the line of sight, it should work. But otherwise,
how does it tell what to focus on? Well, I was right to
worry. I usually have to focus on one spot and then reorirnt
the camera to get the proper framing. Even then, sometimes
it gets it wrong.


Depending on the resolution of your camera, there must be a smallest
area in a viewfinder that can be used for passive ( not light beam
reflection) autofocus. A computer algorithm is used to decide on the
optimum value of some function and must have enough pixel values to
reliably calculate. I have wondered about the various functions. How for
example does the Nikon "Museum Mode" work when it takes 12 non-flash
pictures and decides on the "best"? It is often quite effective.

James, I can't find anything on Museum Mode taking a dozen shots. Can you
help me with a link to a discussion about that? Thanks.


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