As AKSAR states, binos are better, but when your space and weight is very limited a monocular does work. You can't go wrong with Steiners.

I have used them a good bit tactically, and I used them as much at close range as I did for distance. Mostly looking for signs of IEDs and boobytraps. It can be useful in tracking as well.

I do not remember the brand, and I can't seem to find them now, but I once used a telescoping monocular that was rubber coated and could work at close range. It was very nice.

I generally carry Steiner Predators now. Small and fairly light, but durable and sufficient for what I need.