For eyepieces, Field of view in deg = field stop diameter in mm of eyepiece x 57.3 / telescope focal length in mm.
For cameras, replace field stop diameter with sensor dimensions.
E.g. Field of view in deg = sensor dimension in mm x 57.3 / telescope focal length in mm.
To work in arc min multiply 57.3 x 60 = 3438. You were close with 3460. If you want even more accuracy instead of 57.3 use 180/Pi = 57.2958 but you will find you 1000mm focal length of the telescope will have more variation so 57.3 is sufficient accuracy.
See
http://www.televue.com/engine/TV3b_p...n=Advice&id=85