

-----------------------------------

neox

05 Mai 2010 23:50



-----------------------------------

Elementary Watson ! :lol: 

Uite o metoda invatata din "Care of astronomical telescopes.. " a lui Pepin Barlow (nici o legatura u Barlow, lentila  :) ). 

"Place the ocular being measured straight (use no diagonal) into a defocused small telescope
in front of the eye, and turn it to face a brightly lit wall on which a measuring tape or
stick has been mounted. (The defocused telescope has no optical function except to concentrate
the light, sharpening the view of the field stop edge to increase accuracy.)
Facing the scale on the bright wall with both eyes open, the composite view obtained will
be the image of the bright field circle seen through the eyepiece, superimposed over the
scale. Center up the circle, and note the diameter of the field circle on the scale, along with
the exact distance to the scale from your eye. Taking D as the diameter of the bright circle
seen on the scale, and r as the distance from your eye to the scale apply the formula:
120 tan&#8211;1 [D/(2r)]. This will accurately yield the apparent field of the eyepiece as used in
any optical instrument."

