That would be possible with both the 1 or the 3 rpm motor. The 1 may be the better choice simply because it would have a higher gear ratio and thus will have more resolution for extremely small moves (if you are looking to get many many shots over the course of an hour). In other words it's not necessarily 'slowness' your looking for here it's how many slices you want to divide that 15 degrees/hour. If for example you were taking a shot per minute and thus dividing that 15 degrees in 60 shots then you'll be fine with the 3 or the 1 because your only asking for .25 degrees per shot which is well within reason. On the other hand if you wanted say 300 shots per hour or .05 degrees per hour the 1 rpm motor would perform this slightly better than the 3 again because of the high gear ratio and thus higher resolution that it can achieve. In any case what your asking for is easily achieved with our system..