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For people who are strongly glasses-dependant, the simple act of focussing a camera, digital or analogue, is a problem. If you are entrusted to take the shots for some important life event, it can be downright terrifying because you just know that many of your shots will be out of focus.
are tiny (about the size of a period . ), radar reflective in a very narrow wavelength, adhesive metal dots which are applied to the forehead (between the eyebrows - unless your family circle is Unabrowed).
A narrowly focussed radar unit in your camera receives feedback from the dot and gives information to the lens drives to exactly focus the camera on the subject at which it is pointed.
The dots come on small squares of waxy paper, which you simply dab on to the principal players in the life-event. They are too small to be noticed in any but a forensic examination.
[po, Nov 26 2005]
Pre-shot focussing no longer needed
For those too lazy to manually focus, or who don't trust auto focus - take a looksee. [fridge duck, Nov 28 2005]
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||If red-eye reduction can be done automatically, I don't know why cameras can't simply figure out where the eyes are, and focus on those.
||The only real answer is to switch out your camera's focusing screen for one with a split-circle, so you can manually check the camera is focusing correctly.
||Face priority focus and metering, using facial recognition, is available in some point-and-shoot class cameras. Nikon makes one that recently hit the shelves.
||No need for radar reflectors.
||More than faces, you do specifically want the eyes to be in focus. Not much use if the nose or ears are in focus but the eyes aren't!
||My 15 year old Nikon gear (F801 and F4
bodies, SB24 flash and Metz 60CT4
flash with AF-illuminator SCA adaptor)
can take a picture in total darkness and
get it in focus. It does this by using an
autofocus illuminator which is activated
upon shutter button press - in this
case, a red LED throwing a pattern of
vertical grating - and the AF mechanism
in the camera will see this and
autofocus on it.
||The other thing is, many cameras have
a viewfinder dioptre adjustment. The F4
viewfinder has a knob for it. My uncle,
during the summer, showed me a small
(35mm) pentax pocket camera that he
complained couldn't be used unless he
took his glasses off. I noticed that even
this little camera has a diopre
adjustment, which gave him an entirely
new view of the camera.
||That New Scientist article seems a little in error or, perhaps, overly simplified. Plenoptic cameras create imagery that can have their depth of field changed after the shot is taken but that doesn't necessarily mean that the desired focus will ever be found.
||Also, the effective resolution of a plenoptic camera is limited to the number of lens elements used in the device. A 90K pixel image isn't too sharp (of course, focus may not be much of an issue at all at this feeble resolution).
||I would think it easier to have several image sensors receive light via partially-silvered mirrors; depending upon how the sensors were placed, they could have slightly different focal distances thus ensuring that when you took a picture, at least one sensor would be in tolerably-correct focus.
||More simple, you can get camera with Dioptre adjustment to correct focus problems for people with nonstandard eyes. If these are not powerful enough, I tink you can get dioptre modifying lenses to go over the eyepiece of the camera.
||The thing is that more and more people don't use optical viewfinders so the diopter adjustment is pointless. Automated focusing systems are an area that can eternally take advantage of advancements in the art.