Here are some tips from my rangefinder webpage. They explain why hard targets (reflective) like rocks or buildings work better than soft (non reflectvive ) targets like deer or tree leaves.
1. Weather conditions - rain, dust, and high humidity will limit the ranging capabilities.
2. Lighting conditions - low light gives the best ranging conditions.
3. Target size - the bigger the target, the better chances of ranging to it.
4. Target reflectivity - Brighter targets, such as white, ranges great; black colored objects range poorly.
5. Target surface - The actual material of the target will affect the range performance - a flat, smooth sign is much easier to range than a matty haired animal.
6. Angle of Incidence - The angle at which the laser hits the target also makes a difference - the closer you are to reflecting the laser off the target at a 90 degree angle, the further you can range.
7. Hand steadiness - this factor will obviously vary from person to person. You think you have a steady hand? Take a laser pen pointer and try to hold it steady while aiming at a far wall. You will be surprised at the amount of movement. The laser is the same way. It illuminates a bigger spot than the pen pointer but you are ranging 1000 feet or more. It doesn't take much movement to have the laser on a different target than what you intend. This will become even more of a factor as people upgrade to longer ranging devices. Realistically, you should expect to range to a deer no further than 275-300 yards with the Yardage Pro 400.
Believe it or not, as you use your range finder more and more, you will learn subtle tricks to help you range further. You want to know some tricks to ranging further? Well okay, here goes:
1. Know your targets, know your range finder. Only experience will help you here. It took you a while to learn to hunt , it takes a little time to learn the range finder (fortunately, not nearly as long as the previously mentioned feat).
2. Keep your range finder as steady as possible. Pretend you are taking a picture; use the same techniques for stabilizing your range finder as you would for stabilizing your camera. If you are having trouble and suspect hand tremor as a reason, then brace against a tree if one is available.
3. Do not attempt to range to an object with the sun directly behind it. The sun emits a lot of radiation at the wavelength of the laser. Minimize the bright conditions as much as possible. Never point the range finder directly at the sun.
4. Utilize the ZIP mode, which filters out ranges less than 120 yards.
5. If rain or dust is obscuring the target, use the RAIN mode.