The Basics on Using a Rangefinder
Your basic rangefinder, whether for hunting, golfing, or surveying, should at least have a scan mode. This enables you to depress the scan mode button, or otherwise continuously enable scan mode, then slowly survey the landscape. The reading will indicate the distance to the focused object. For example, in golf, you may scan the trees behind the pin, then see the reading jump up when you scan past the pin. Plenty of other modes are available, but this is the basic and most frequently used.
Plenty of other options
Technology being what it is today, rangefinders are capable of doing much more than scanning landscapes and reporting the distance. A horizontal mode is probably the next feature you'll want to have on your rangefinder. Essentially, the optics in the normal scanning mode are best suited to measure horizontal distances, but this mode allows you to gauge vertical distances as well. Of course, options are nearly unlimited, with readouts on your range finder screen indicating everything from recommendations on rifle angle, scope positions, and loads of others. These are nice, but you would probably be best served by saving your money when it comes to these add-ons.
Some common uses of rangefinders
Generally, rangefinders are used for gauging distances in hunting, golf, and surveying. Since very precise surveying equipment is better suited for that purpose, we'll assume you're a hunter or a golfer. While all rangefinders magnify the image by six or seven times, they should not be considered a replacement for binoculars. Magnification is a completely different function that is best served by a separate device.
The basic rangefinder for purposes of golf are those that offer decent power, good picture quality, and a modest power rating. The picture quality is never going to be as good as a hunting range finder, because the purpose is completely different. The range, too, will generally be less since targets in hunting range further than golf holes.
Speaking of power range, beware the manufacturer's claim on the box. It always refers to the range in perfect atmospheric conditions, which will almost never be the case when hunting or golfing. Anticipate always being able to range a deer at about a third of the stated maximum range and almost always at about half the range. For golf, things get trickier because the pin such a narrow target. Be sure to read the fine print about the range finder's performance.