Distance to the bird: appr. 100 m. Focal Length: 39.0 mm through 25x. Anyone who knows how to calculate the focal length through the scope?

Yes, just multiply the scope magnification with the focal length of the camera lens.

Digiscoping using an SLR - how do you obtain correct focus?
Manually?
Using live-view contrast detection?

B.r. Stig.

PS. Nica photos from Oman.

Sorry, nice - not nica.

Ok, thanks! Didn't know it was that easy. :-) That will say, 39 mm through 25x eyepiece is corresponding to 975 mm. Impressive!

Well, obtaining the focus isn't that easy. The AF doesn't work when the camera lens is docked to the eyepiece, so you simply have to use the scope's focusing mechanism. Apparently, the rate of sharp images will be higher when using the Live View function instead of the optical viewfinder. The resolution of the TFT-screen is so good that it's way easier to use than i.e. the screen on the old Coolpix compacts.

I suppose that the rate of sharp images will be even higher if you use an adapter, to center the cam lens in front of the exit pupil of the eyepiece.