There are many premium quality lenses out there. Best lens to use is a versatile 24-70mm zoom lens. It allows you to take family group shots in most environments, as well as showing the whole body of a newborn and close-up portraits of babies' faces. Unlike commercial assignments, photographing newborns is personal, intimate and much more artistically satisfying.
Unless you are working in really low light, you are unlikely to need the higher ISO sensitivities of the best cameras; and although the focusing options of newer cameras are sensational, if you use a mediocre lens you will never get the real wow factor in your photographs. In the case of newborn macro photography, a longer focal length is better, as it will allow you to work with a greater distance. The lens can also produce a beautiful bokeh, resulting in a blurred background, which is very attractive for newborn photographers. With its wide aperture of 1.8 (which means it can be used in low light), this lens is perfect for capturing the first moments with your new baby.
An 85mm lens is awesome for portraits. It's also great for photographing babies, although in a home environment you're unlikely to have enough space to use it for full body shots. You will find that the bokeh of this lens is very smooth and creates a nice background for your photos. To take a sharp image with excellent bokeh (blur), this lens has a wide maximum aperture of 1.4 and a fast focusing speed to capture snapshots of youngsters being held by their parents or grandparents. No doubt, a good camera and a good lens will go a long way to getting a great picture, but they can't do the magic.
With the help of FLD and SLD, this model minimizes the amount of distortion, which is a common problem for most wide-angle lenses. For newborn photography it works perfectly well and is comfortable, as you can work with this lens in a very small space. Other lenses that I sometimes use for baby photography are the 135 mm lens, which requires a lot of space, so it usually has to be used outdoors.
More on this topic here: "What lens should be used to photograph a newborn"