Agreed, but I was really only using the sports analogy as an example of
f-stop use because I assumed it would be familiar to people and they
could visualize what was being described much better. ;) The ultimate
point being that f-stop isn't the "controlling factor" for sharper
photos though it's related. Also, you don't need a digital SLR to make
crisp clean photos. (though it helps) A simple point and shoot camera
will work great if you know how to maximize it's settings to get the
best results.
Regards,
Eric
On 1/27/2010 10:44 AM, Matson, Robert D. wrote:
Hi Eric, Al, Erik,
Erik is right, The higher f-stop of 22 will increase depth of field
...
Yes.
... not sharpness of focus.
Unless you have a very good lens, it will ALSO increase sharpness of
focus for stationary objects.
This is why sports photographers use a low/large f-stop lens like
f2.8 lenses.
(f/2.8 is actually not that fast a lens for a professional. f/1.4 is
a fast lens.)
The reason is simple, the smaller aperture only allow focus on a
small area of the subject, blurs out the background and has a
very shallow DOF ...
All of these points are true, but that's not the main reason sports
photographers use low f/#. In sports photography, short exposure times
are crucial so that action isn't blurred. This cannot be achieved at
high f/# because the stopped-down lens doesn't let in enough light
for a properly exposed image. That said, professional photographers
usually do NOT use the fastest f-stop of a lens since the lens
periphery has the maximum optical aberrations. An image (of a still
object like a meteorite) taken at f/1.4 using an f/1.4 lens will
rarely be as crisp as an image taken with the same lens at f/2.
Best,
Rob
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