On 2010-12-29 13:47 , Eric Weir wrote:
On Dec 29, 2010, at 12:47 PM, steve harley wrote:
well, it could be the lens, but if the image appears very sharp in the viewfinder,
but comes out blurry, your camera may be back- or front-focusing (viewfinder not
properly coordinated with the actual focus on the sensor); some simple tests on a
tripod can confirm that (the classic is to prop up a yardstick at 45 degrees and
focus on the 18" mark)
[1] Does this mean it might be correctable?
from what i've heard, it is often correctable
[2] When you say "at a 45 degree angle, do you mean relative to the focal
plane, pointing away from the lens?
yes; if you read email in a monospaced font, i mean like this
/
x---/
/
How far away should the yardstick be? What will be the indication of back- or
front-focusing when I do this?
it doesn't have to be that far, but the farther away, the more precisely
it will measure, and a large aperture (shallow depth of field) helps; if
the viewfinder shows you've focused on 18", but the resulting image has
16" in best focus, you'll know that the viewfinder is not accurate
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