I have a Berger transit that needs calibration. When leveling, using the two small vials on the plate, they change when reversed and re-leveled several times. The scope level also changes slightly when turned 180. This is the question. When using the transit as a level, and I level the scope level, should I re-level it when I turn it 180 or just use it slightly out of level.? In other words, should I re-level the scope bubble every time I turn the scope for a shot?
Yes, but ....
The first thing to do is get the 2 plate levels adjusted as closely as you can.
Then you adjust the telescope level as closely as you can.
But from there the reason you would want to tweak the telescope level when running levels is because the plate levels are really not sensitive enough to really get things level.
I would run a two peg test. This will tell you how far your level is out of calibration.
Err... Transit
Let me re-state my question. I do level the plate bubbles as close as I can, but they never get the the point where you can turn them 180 and stay level. I understand that the scope level is more sensitive.
My question is, should I re-tweak the scope level every time it goes out of level due to turning it?
The answer is still yes. You should be checking the scope level on every shot and adjust as needed. You should be able to level the instrument with the plate levels. The bubble may not be in the center at that point but it will be the same as the instrument is turned in any direction.
To adjust the level tube/bullseye you should adjust the instrument so the bubble is centered, rotate 180 degrees (which doubles the error), and take out HALF the amount the bubble is off by adjusting the screws on the tube/bullseye.
Then relevel the instrument to center the bubble, rotate 180 and check that it stays centered.
When your three level bubbles are adjusted property, they will stay in place whichever way the scope is pointed.
Apart from going thru the procedure of adjusting the bubbles, you would average the the bubble's location at for and aft directions and you would be closer than leveling the bubble every time you point it in a new direction.
good luck
> Let me re-state my question. I do level the plate bubbles as close as I can,
Remember to only take out half of the difference for each adjustment. At some point you are going to reach the limit of the equipment, your tripod, the ground you are on, etc.