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2thdrswife Sep 23, 2008 9:58 AM

I dont know the right terminology, but I see all these pictures where everything in the picture is in focus. I LOVE LOVE LOVE my D40x, and know how to use the focus spots, but I want pics of the main subject as well as the background to be in focus....

JimC Sep 23, 2008 10:55 AM

Welcome to the forums.

You want greater depth of field (how much of the image is in focus as you get further away from your focus point). See this handy online Depth of
field calculator for a better understanding of how focal length, focus distance and aperture impact DOF (Depth of Field).

You'll want to take a shot of your subject where you're capturing a wider angle of view with the main subject occupying a smaller percentage of the frame (versus a tighter head and shoulders shot) to maximize depth of field for a given aperture. You can also use a smaller aperture (represented by a higher f/stop number) to get more depth of field (although you will have limitations). Simply shoot in Av (Aperture Priority) mode and select a higher f/stop number, letting the camera pick the best shutter speed to use.

But, keep in mind that if you use a smaller aperture (higher f/stop number), you will get slower shutter speeds (which can allow blur from subject movement or camera shake if they get too slow). So, be aware of your shutter speeds when using smaller apertures, as you may need to increase your ISO speed (which is how sensitive the sensor is to light) to keep shutter speeds as fast as desired (and increasing ISO speed increases noise). See this handy online exposure calculator to get a better idea of how your aperture impacts the shutter speed you need for proper exposure:

Also, be aware that if you go too small (for example, much over around f/11 or f/14, depending on the lens), you will start seeing softer images with some lenses due to diffraction, so you'll want to avoid aperture extremes. Most lenses are sharpest with their apertures set to around 2 or 3 stops down from wide open.

So, you'll want to balance the need for greater depth of field against the need for the sharpest subject, and you'll also want to consider how slower shutter speeds may impact your images when making decisions about what aperture to use, increasing ISO speed as needed to help prevent blur if you're not using a flash or tripod, depending on the lighting.

tjsnaps Sep 23, 2008 7:30 PM

First of it would help if we knew what you were shooting pictures of.

If your subject is static then you wont have to concern yourself with motion blur from the subject. But you will need to be concerned about it from the camera. there is an old saying "Your first lens should be a tripod" Meaning that a tripod is the most important thing you can own to achieve sharp images. It will allow you to use slower shutter speeds and stop the lens down for greater depth of field.

Unfortunately many modern AF zoom lenses do not have a distance scale or a depth of field scale on them. But if your shooting landscapes you might consider getting a wide angle lens that does. This way you can use the hyper focal distance for maximum depth of field. I will explain this below if you care to know.

For other subjects you are stuck with using the smallest aperture you can get away with and hoping for the best. But again a tripod can help. A small amount of subject movement is not as bad as camera shake.

Hyperfocal distance

NOTE: this must be done in manual focus

It's simple, the focusing ring on the lens will have a scale of feet and meters. On top of the lens will be an indicator to tell you the focus distance. To the left and right of that indicator will be F/numbers. That is the depth of field scale. It will look something like this.

16 11 8 5.6 * 5.6 8 11 16

The number on the distance scale that is next to the indicator is the focus point . Every distance on the focus scale that is between the numbers on the DOF scale representing whatever F/number you are using will appear do be in focus. Now lets say you are using F/ 16. Focus on the farthest thing you want in focus. ( normally for landscapes this would be infinity ) now move that distance from the indicator to the 16 that represents the far end of the scale. Now you have the maximum focus and depth.

Nagasaki Sep 24, 2008 5:28 AM

Unfortunately the depth of filed scale described by tjsnaps is extremely rare on modern autofocus lenses. A great shame because it was a useful tool.

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