You can even use this method to somewhat use your binoculars as a makeshift rangefinder. Have your friend stand at 25, 50, 75, and 100yrds. Look at him through the binoculars, and put his FEET at the very bottom of your view (like he’s standing on the bottom of the circle). Write down approximately what percentage of the height of the view his PANTS cover. So say at 25yrds, his pants cover 2/3 of the view, at 50yrds they cover 1/3 of the view, and 100yrds, they cover 1/6 of the view. Now you’ll know if you spot a deer, and he covers 1/2 your view, he’s probably about 35yrds away.

Then you can practice estimation by having him move to different random positions on the field (he’ll know the range, but you won’t). You can make a guess, then see how close you are to correct.

Also while you’re on the field, practice striding out in yard increments. That way when you’re NOT on a football field, you can still rough measure with reasonable accuracy, just by walking it out.

You can practice by estimating the range across a parking lot, or a yard, open field, etc etc, then walking it out in strides/yards. Have your friend run out somewhere random, across a field or parking lot, then guess his range, and then walk it out to see how close you were.

Before hunting season starts, if you’re hunting in a predetermined location (i.e. placing your blind or stand), then you can use a 100ft or 300ft tape measure to measure off different landmarks in the area. I always draw maps of my hunting areas, and then mark certain landmarks. I’ll hang orange contractors flagging tape in trees or on fence posts that I’m using as landmarks as well, so I can quickly gauge “oh, he’s halfway to the 100yrd tree, so he’s 50yrds”. You can also use Google Maps to help measure distances as well. You can select different points on a satellite view, then measure how far apart they are. (I make all of my hunting maps in google maps. I take GPS coords of my stands, then GPS coords of different landmarks, then use the measure function to estimate distances. I confirm the distances in the field with a laser rangefinder.)

If you’re hunting over beanfields or corn fields, then you can sometimes count crop rows (2.5ft per row). Although it does take a long damn time to count 200yrds of rows (240rows), and it’s easy to miss a few. Irrigated ag fields with a center pivot are also helpful, because a typical pivot is about 1250-1300ft long, or about 400yrds. If you’re on the field edge, and they’re half way to the center pivot, then they’re 200yrds away. In many parts of the country, ag fields or even pasture are broken up in either 40, 80, or 160 acre patches. 40 acres is typically 400yrds by 400yrds, 80 acres are usually 400yrds by 800yrds, and 160 acre patches, or 1/4 square mile, are 800yrds x 800yrds. So if you’re positioned half way along the long side of an 80acre patch (400yrds from each end of the 800yrd side, and 400yrds from the far side), and a deer walks out half way between you and the fenceline along the same edge, you know he’s about 200yrds away.

Good luck and happy hunting!

It takes some of the guess work out. I also have a laser range finder, its usually left on the floor in the truck with flat batteries.

Last year I was out with another guy, he had a fancy Zeiss scope. When you pressed a button on the side the distance to target was displayed in the scope.