Nikon D5100 with 18-55mm lens...need help with focusing please!

[Stars]

Hi there,

I currently started reading Understanding Exposure (3rd Edition) by Bryan Peterson.

The book advises that I should have my camera set to Manual - which I have done - but I am concerned with why my images are coming out all blurry despite having the correct "exposure"?

I am unsure as to what setting I should have for my focus on both my camera (AF-A, AF-S, AF-C or M) and lens (A or M).
I am also concerned because my hands are slightly shaky - that it could be causing the blurriness as well.

While I understand that not all my images will come out perfect as much of what I'm doing is expermenting; I would just like to ensure that I'm starting off correctly on the right foot and it is not a bigger issue that I may not know of.

Any help would be greatly appreciated!

Thank you!

 

[tirediron]

There are several possible causes of blur. One is too low a shutter-speed which will allow the camera to move; even a tiny movement will cause blurring, and if your hands are shakey, this will amplified (I would suggest keeping your shutter-speed above 1/125). The next is shallow depth of field... the larger the aperture you use (smaller f#) the less distance is in sharp focus. Check out this calculator for a more graphical expalanation. Lastly is incorrect focus. Modern DSLRs generally auto-focus well, but they don't always choose the point to focus on that we want them to. I generally use AF-S with a single focusing point, which I place over the area of critical focus. I'm not overly familiar with the D5100, so you'll have to read your manual for more detail on that.

Hope that helps.

 

[SCraig]

I am unsure as to what setting I should have for my focus on both my camera (AF-A, AF-S, AF-C or M) and lens (A or M).
I am also concerned because my hands are slightly shaky - that it could be causing the blurriness as well.

AF-S is single servo focus. When you push the shutter release halfway down the lens will autofocus and it will not change until you release the shutter release and push it halfway down again. Primarily for static subjects that are not moving.

AF-C is continuous servo focus. When you push the shutter release halfway the lens will autofocus, however if the point of focus changes the lens will continue to focus. Primarily for subjects that are moving however works just fine for static subjects as well. This is where I leave my camera set.

AF-A decides whether the subject is moving or not and picks single-servo or continuous-servo as needed.

M is manual focus where autofocus is disabled.

On the lens A means autofocus and M means manual focus. If you put the lens in M then autofocus is disabled.

Your shutter speed on that camera should not be less than 1-1/2 times the reciprocal of the focal length of the lens. If you are using a 100mm lens your shutter speed should not be below 1/150 second. If you are using a 50mm lens your shutter speed should not be below 1/75 second. These are rough rules of thumb and using VR (vibration reduction) will reduce those requirements, as will using a tripod or monopod or bracing your hands on a wall, tree, or whatever is handy. Hand shake does not help at all, and I strongly recommend you brace your hands against something whenever possible.