JPeoples wrote in post #3033820
My wife is a very new beginner with a new Rebel XT and she loves portraits (of course) and especially baby Grandchildren. She wants the back ground blurred just as your example is but with her 50mm 1.8f lens (new) she is not getting the same results. She has tried many aperature settings and has tried shooting from three feet to ten feet away from the subject. She shoots in auto or P mode setting the ISO to either 100 or 200 to compare. How close were you in the shots you have posted? Do you have any suggestions for her? She does get the blur when using her 55-200 lens in outdoor shoots. Any help is greatly appreciated since it would get me off the hook for learning all of this.
For your wife:
To get the most shallow depth of field possible, do two things. First, put the camera in Av mode (Aperture priority mode, allows you to control the aperture and the camera will set shutter speed to match). Second, turn the dial to bring the aperture value down to 1.8. This sets the lens wide open (largest maximum aperture). Third, get as close as possible.
As far as how close I was to my subject in those photos ... what you see is what you get. Those photos are not cropped. I was either at, or very close to, the minimum focusing distance of that lens which is 1.5 feet.
However, even at 3 feet, the depth of field should be sufficiently shallow to throw the background out of focus assuming the background is not less than a foot or two behind the subject.
First off, in Auto mode, you cannot control the aperture. The camera does that on it's own and in my limited experience with camera auto modes, they tend to default to slow apertures typically around f/4 to f/8. In P mode, you also don't directly control the aperture .... instead, you semi-control it and shutter at the same time ... but not really. Go into Av mode, that's going to be your key.
Can you post an unedited photo online for us to see? If left unedited, the EXIF data should still be intact and we can tell you exactly what aperture value the camera used for any shot in question.
Bill