Hi, I saw mentions of this above, but I thought I would state it again.
In order do maximize the drift time in your scope you are looking to maximize the true field of view. If everything else is constant TFOV decreases as you decrease the the focal length of the eyepiece. (hence increase the magnification).
To calculate the true field of view use this formula.
TFOV = field_stop_diameter / focal_length * 57
If you have an eyepiece with a field stop of 10mm and your scope has a focal lenght of 1200mm then your true field of view is 10/1200 * 57 = .475 degrees.
Now many eyepiece vendors do not publish the field stop diameter. You can measure it yourself. Flip the eyepiece upside down and see there is a baffle the restricts the size of the filed lens (lens that points toward the "field") Also Don Pensak has an eyepiece buyers guide (in the eyepiece forum) that list hundreds of eyepieces and many have field stops.
There is another way to calculate the field stop which is not as accurate but close.
TFOV = apparent_field_of_view / magnification.
Putting in numbers for a 50 degree 10mm plossl in your scope it works out to
TFOV = 50 /.(1200 / 10) = .420 degrees. You can notice that if an 80 degree eyepiece
is plugged into this equation the TFOV increases to .666 degrees. So if the 50 degree
eyepiece has a drift time of 30 seconds, the 80 degree eyepiece will have a drift time of 48 seconds.
One other thing to note is wide field eyepieces are difficult to make and have low distortion in the outter portiion of the field. Also newtonians have coma as you move from the center of view. So a widefield eyepiece will decrease bump time, but may interject other abberations in the outer field of view.
Regarding motions, I'm not sure what system your dob has for altitude, (springs or bearings) but if you take the tension off make sure the dob is pretty well balanced
with your typical accessories. If it is not get a welding magnet and attach it to the tube
at the right point to get good balance.
Regarding azimuth. If there is a speed bump thing going on there is definetly something
going on. First make sure the base is level when you observe, otherwise you are pushing it up a hill or down a hill. A star hopper??? Is this a used scope? Are the base boards flat? or is there some warping? With a lazy susan there should be almost too little friction.
I have to put a small square of carpeting between my boards to increase friction.