Re: Using LCD screen to shoot photos in DSLR

X-Man wrote:
On Sat, 21 Jul 2007 10:20:49 -0600, "Roger N. Clark (change username to
rnclark)" <username@xxxxxxxxx> wrote:

"Live preview" is a marketing ploy that is exactly the opposite
of what it really does. The time to read data off the sensor
and display it on an LCD should actually be called
"Delayed preview." The only true live preview is the
the optical view a DSLR gives, delayed only by the speed of
light. Sports and wildlife action photographers use
optical true live preview of DSLRs. To degrade to
LCD "live preview" would result in many missed images.

Roger

Only untalented snap-shot hacks would not learn to use their tools properly.
Missing shots and then blaming it on the camera. They're the very same people
that have to spend $5,000 on photography equipment so the cost will magically
turn them into a photographer. They can never seem to spend enough to try become
a photographer, always wondering why their camera is never good enough to make
them into one. I fail to see where a preview-lag that matches the same speed as
the shutter would in any way make someone miss a photo. The only thing you can
blame is the speed of your own neuron activity, the ones mostly between your
ears. Perhaps this is why you keep believing this, look at what is telling you
these erroneous things. Your own mind trying to compensate for its own drastic
and self-crippling limitations.

This troll has demonstrated it knows nothing about the delays in various
cameras, nor why professional wildlife and sports photographers
use high end DSLRs.

Cameras with "live preview" must work in a fast, lower grade
video image mode to get data off the sensor. These cameras
typically use this video rate to autofocus, so when you
press the shutter button, the camera must hunt for the
best focus limited by the video rates from the chip.
Once focus is achieved, the video mode is stopped, the
pixels electronically "erased" and mode changed to
acquire a full resolution image. Then the shutter
is opened (mechanical or electronic). During this time,
the subject, when imaging action, has likely moved and the
focus is now off.

In DSLRs, separate AF sensors monitor and track focus when the
mirror is down while you look at a true live preview: the optical
viewfinder. The system tracks focus on moving subjects and when
you press the shutter button, the focus position is predicted
for the time the shutter actually opens, including calibrated and
known delays of raising the mirror. The time to raise the mirror
and expose the sensor in fast DSLRs (about 50 to 60 milliseconds)
is small in comparison to the time to stop video feed, prep the sensor
and expose the sensor in a "live preview" camera.

Roger
.

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