producing really sharp images, this means using lenses that are fast enough (have a wide enough maximum aperture) for their purpose and having enough light in the scene so that they can be used somewhere in the middle of their aperture range. If you are shooting in mostly low light situations where you have to shoot wide open, you probably won’t be able to achieve really sharp images. One way around this is to increase the camera’s ISO settings to allow for shooting one or two stops down from wide open. If you can control the amount of ISO increase to one or two stops, you will probably achieve acceptable sharpness. Using really large ISO numbers usually introduces an element of "noise" or "grain" to the image. So, you want to stay away from ISO numbers that are much higher than around 2500.
I use this principle when I shoot concert photographs where there is little or no stage light.
This image of singer/songwriter Lucy Kaplansky was made with an 85mm f/1.8 lens at 1/125th of a second at f/5.6 using an ISO setting of 2000. This f/stop setting was more in the middle of the lens' aperture range and because of the high ISO setting, I didn't have to use the lens wide open. I had enough speed to stop the action and the image has enough sharpness to make a large print.
And, here is an image made with a studio strobe unit which put out enough light to allow and ISO setting of 100 and an aperture of f/22:
Note that focus is carried almost from the very front of the guitar to the very rear. This was shot with a Canon 60mm Macro lens. The camera was mounted on a tripod for extra stability.
Now, with all this being said, there are other factors that could cause soft images. They are:
-Unsteady camera - Use a tripod or a monopod.
-Slow shutter speed - Make sure your shutter speed is
fast enough for you to hand-hold the camera. You can
increase your ISO a bit to yield a higher shutter
speed.
-Improper autofocus settings. - AI Servo is probably
the best.
-Check your autofocus points as well. Probably best to
use one point in the center so that your AF doesn't get
fooled that often.
-Use your camera on Manual rather than P or A.
As I have said, it's important to know that if you use a point-and-shoot camera, they almost always come equipped with a zoom lens. The better ones will have a fast zoom lens that carries its largest aperture through all of the focal lengths. So, that's something to look for if you like these kinds of cameras. Otherwise, you may end up with unsatisfying results as to sharpness. The old adage of "you get what you pay for" definitely works here.
All of the above techniques should ensure fairly sharp images overall. In order to really check for sharpness I recommend making 8x10 inch prints. We are so used to seeing images on one kind of screen or another that we are sometimes fooled into thinking that an image is sharp when it is only marginally so. If you make a print, you will know immediately whether it is sharp or not.