My guess is that for a barn or something you probably have a single 30 amp run (10 guage wire). This is pretty typical for an out building used as garage, and in NY would meet code in most situations. For the distance you have there will be a 3 or 4 amp drop, and there is probably a another 1 amp drop due to connections. So for your machines you should be fine power wise, but you should not have your lights dimming, especially the bandsaw. For a 2 hp machine on 220 max draw should be less than 15 amps, your lights, if you have a lot of them, should draw no more than 2 amps, radio, fan, wall clock, glue pot, etc., another 2 amps. So worst case 19 amps. Your lights should not be dimming. The 2 incandesents over my bench don't dim when I power up my planer with the DC running (8 hp total).
Check your wiring to see if it's aluminum. If so there should be a special grease on the connectors to keep the aluminum from corroding. In a shop the grease could get full of dust and dry the grease out. A lot of home fires have been blamed on aluminum wiring, which is why it can no longer be used in NY for anything less than a main run, and is coded oversized (i.e. where the math calls for 8 guage, you have to use 4 guage). If you have aluminum for you source swap it out for copper.
I agree with what kerry and farms posted. If there are no obvious problems (loose wires, corrosion, moisture in a box) call an electrician. It probably is just current drop due to distance. If everything is safe, which it probably is, the electrician can let you know what you need to do to have adequite power. And If it's not safe, you'll be really glad you called him. The $100 or so it will cost will be much cheaper than redoing something that isn't a problem.