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From: rwp@hogpc.UUCP (R.PAUL)
Newsgroups: net.rec.photo
Subject: Re: sharpness
Message-ID: <420@hogpc.UUCP>
Date: Wed, 23-May-84 10:58:36 EDT
Article-I.D.: hogpc.420
Posted: Wed May 23 10:58:36 1984
Date-Received: Sat, 26-May-84 11:19:59 EDT
Lines: 87

[]
The hints I will mention on getting sharp negatives will probably
be obvious to the more experienced photographers in this forum, but
they may be helpful to some.

To begin with, the mechanisms for getting sharp negatives depend, to
a great extent, on the type of photographs you are trying to take.  There
are different things that can and must be done to get sharp negatives of
scenic views, insects, action shots, and portraits.  I will try to note
with the techniques I mention the types of photography to which they can
be applied.

Techniques:

1) Lense choice - whenever possible use the camera's normal lense (about
50mm).  The maximum aperture of such a lense should be approximately f2
for maximum lense sharpness.  This is good for static subjects at a com-
fortable distance in good light (e.g. daylight).  However, if the subject
is small or very flat (e.g. writing on a piece of paper) a macro lense
(again about 50mm) would work better.  Macro lenses are generally optimized
for flat field sharpness.  The maximum aperture will probably be significantly
smaller (about f4.5).  For sharp photos in low light, a fast lense is
recommended.  For a normal lense, the aperture might be anywhere from f1.2
to f1.8.  For a 135mm telephoto lense the range might be f2 to f3.5.  For
action shots that really require a zoom (e.g. sports), the range might be
f2.8 to f3.8.  Zooms are not recommended for getting sharp shots.  However,
in some situations, they may be required.

2) Shooting aperture choice - when possible, shooting aperture should be
approximately the midpoint of the aperture range of the lense being used.
Wider apertures suffer from lack of field depth and smaller apertures
suffer from chromatic aberation.  On a normal lense, this would be about
f16.  This, of course cannot be applied to low light photography.  It
usually does not apply to action photography in any light.

3) Use a tripod and cable release - this can only be applied to relatively
static subjects (I include portraits in this category).  No matter how
steady your hands are, they shake more than a sturdy tripod.  Camera shake
is probably the second most common cause of sharpness loss (the most common
is probably the use of a too slow shutter speed).

4) If a tripod is not available or not practical, brace yourself and your
camera - use a wall, a sturdy chair, a tree -- anything that will help you
gain stability -- to make your body more stable.  If nothing is available,
at least make sure you have a firm stance (one foot slightly in front of
the other ...) and a firm, but comfortable, grip on your camera.

5) Shutter speed choice - if your subject is not completely static (this
may even apply to scenic photography on a windy day), choose a shutter
speed fast enough to freeze your subject.  If you are hand-holding your
camera, remember the rule of thumb for slowest shutter speed selection:
no slower than the reciprocal of the lense length in millimeters (e.g
with a 135mm lense, the shutter speed should be 1/135sec or faster).
There is a definite tradeoff with technique #2 here.

6) If possible, immobilize your subject - this applies best to photo-
macrography.  For instance, if you are photographing a flower outside
and at close range, try cutting off the wind around it by placing some
kind of barriers at strategic places.  If the barriers are smartly
chosen the photo may even be enhanced by doing something like adding
fill light or diffusing the light source.  Of course, it is also possible
to ruin the photo by choosing the wrong barriers.  With insect photography
it may be possible to chill it, thus numbing it temporarily, and slowing
its motion.

7) If your camera has a mirror that can be locked up, use it - this works
only with static subjects and very few cameras have this feature, but if
yours does and the subject is right, this will prevent camera shake due
to mirror vibration.  Of course a tripod and cable release are also necessary
to make this technique have any positive effect.

8) Use a fine grain film - this only applies in the best of light, but helps
immensely when it can be used.

9) Use a fast film - this conflicts with #8, but in low light it will allow
getting the best shutter speed/aperture combination for the photo being
taken.  Perhaps #8 and #9 should be combined into one technique saying,
"Use the finest grained film lighting conditions will allow."  Or maybe both
of them should be combined with #2 and #5 to say, "Optimize your choice of
film speed, aperture, and shutter speed."

I hope this list of techniques has been helpful.

				Rick Paul
				AT&T Information Systems Laboratories
				Lincroft, New Jersey
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