This is assuming you don't have a rangefinder with built-in angle compensation...

How's your "off-the-cuff" angle/yardage guessing compensation when bowhunting? Guesstimating yardage is hard enough at times, but throw in a steep upward or downward angled shot and most shooters are stumped.

In the latest issue of Bowhunter magazine - "Gear Special 2008" - there is a very interesting article by a guy named Jack Frost (no kidding!). The article is titled "Ranging Ups & Downs". It highlites a few of the newer Angle Compensating Rangefinders. But. It also provides a tip/trick for those without ARC Rangefinders.

Basically it goes something like this...(or you can buy the magazine for yourself)...
In 1990 a fellow by the name of Greg Piesinger (I don't make these names up - honest) used calculus formulae to generate a table of "hit windows" for various arrow speeds and angle on incline, whether up or down.

Well those formulae and tables were pretty complicated for use in the field so good ole Greg analyzed them and came up with his own table. There are small discrepancies (according to the article) but all that is really necessary to hit the "window of opportunity" ie. the kill zone, was to determine the horizontal distance and apply a bit of math.

Here are the results of Greg's deductions.

If the upward or downward angle is...

60-degree angle: divide the line of sight distance by 2

50-degree angle: divide the line of sight distance by 1.5

45-degree angle: divide the line of sight distance by 1.4

40-degree angle: divide the line of sight distance by 1.3

35-degree angle: divide the line of sight distance by 1.2

25-degree angle: divide the line of sight distance by 1.1

less than 20 degrees: hold an inch below

Obviously estimating the angle of incline is every bit as important as estimating the horizontal yardage for this to work.

So brush up on your math skills or pack along a calculator and get out there in them thar steep hills and "harvest" something!