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Setting circles can be used to good effect for two things
1. Assisting in polar alignment. Set polar axis using latitude scale. Roughly point your mount south. Centre the scope(low power) on a bright star low in the sky for which you know the declination, and note the dec circle reading. If it agrees with the known value, then you are pretty close to the pole. Otherwise shift the dec axis to the correct reading (moving the star out of the field of view). Then slew the sope in azimuth until the star comes back into view. You may have to do this a few times.
2. Once you have the mount polar aligned - sufficient for visual observing, then you can use the circles in conjunction with star charts to find objects in barren areas of sky.
For example lets say you want to find M46. Centre the scope on a bright star nearby - Sirius. By reading and measuring the chart it shows that M46 is 0h 52m east and 2.4 degrees north of Sirius. Shift your scope by these amounts on the setting circles. You should see M46 in the finder, if not the main scope on low power. its easy and was the way of the world before GoTo.
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