A question on finders

I would like to know how to calculate the degree field seen through a 6x50 finder, or similar finder. I'm trying to starhop and if I place a known star on one side of the finder and move the finder to place the star on the other side of the finder, how many degrees have I moved. I have a dob, so I don't have setting circles. Also how many degrees does the three circles of the terad bulleye represent. Thanks

David, the most accurate method is to allow a star on the celestial equator to drift across the field of view of your finder. It will take a while (a 6 x finder with a wide field of view could take nearly 1/2 hour). The best star to use right now is probably Mintaka, Orion's western-most belt star (it's less than 1/5 deg. away from the celestial equator, will give an accurate result). The star will appear to move about 15 degrees every hour, so long as it is well above the horizon. It is important that the star drifts through the center of the crosshairs to get an accurate reading. This will be more difficult to accomplish with a dob mount, so I'm adding a simple chart you could use to get a close estimate of your finder's field of view. The Telrad Circle are 4 degrees, 2 degrees, and the Telrad Bullseye is 1/2 degree across.

Joplin

Attached Image: