This is page 4 of 4. The page begins here.     Please read that page first.

Once you have the shot, put it in your computer and just open it up. You will see any dirt that happens to be anywhere in the light path between the outer most lens and the image sensor surface.

Now figure out where it is, by elimination, and clean it up. There are places in the camera you won't be able to reach. In that case, if you want it cleaned up, you'll have to take your camera to a repair shop.

I strongly urge against cleaning your image sensor unless and until you are either very familiar with cameras or you just don't care whether it gets damaged. To satisfy your curiosity, here's a picture of your sensor.

The image sensor is tantamount to the "film" surface in a film camera. The red arrow points to the mirror. It is held up by a program inside the camera. The blue rectangle beneath that is the sensor. It is very, very sensitive.

Let’s compare when we're taking a picture.

The next two pictures were taken in “Aperture Priority.” First I used f3.5, second f22. Most times I want my subject crisp and the rest of the frame blurred, like the top picture.

This picture, however, I feel should be in focus throughout. In the foreground is the canon. Midway to the mountains are the flags and then in the background are the mountains which I want showing clearly.

I feel the photograph is more effective being in focus throughout. The next one however, I feel is a personal choice. I can see either being preferred.

In the top picture, f5.6 the subject is the background. It is the boats. So blurring out the window frame in the foreground can work.

In the bottom picture, f34 there are two main subjects. The boats in the background and the window frame with the beveled glass, in the foreground are both notable subjects.

For me personally, the bottom picture works better. But it is the choice of who ever is viewing the photograph.

CAUTION; when you are close to your subject and you use a very wide aperture it is likely that part of your subject will be sharply focused and other parts will be blurred. The closer you are, the narrower aperture you need in order to have your entire subject in focus.

For general, hand held shooting go here.

One final thought. In the next series of pictures I set the camera for the correct exposure in the first picture. In the second picture all I did was change the aperture to a very high number. I left the shutter speed the same.

The purpose of this comparison is to show how the shutter speed must change when the aperture changes or the picture will be exposed wrong. The top picture was taken at f5.6 and a shutter speed of 1/400th of a second.

This shot was at f34, still 1/400th of a second shutter speed. As you can see one would have to keep the shutter open much longer in order to get the same approximate exposure as in the first picture.

Finally this picture was set in the middle at f8. The shutter speed was still 1/400th of a second.

There you have it. Aperture, what it is and why we need it when we want professional photographs. Now go out and practice until it becomes second nature.

This whole page boils down to...

Large number, much in focus. Small number, little in focus. So the aperture rule of thumb is, use a large number when you are shooting (large) landscapes and a small number when you are shooting (small) people or animals.

For tripod mounted guidelines go here.

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