I have a swaro monocular rangefinder and scheduled a trip out west for hunting mule deer. I don't have a nice pair of binoculars and was wondering if I could get away with just using the monocular. I'm thinking by using it, there will be alot of strain on my eyes. Has anyone had any experience using this for long periods of time glassing? or should I just invest in a nice set of bino's too?