How to calculate the magnification?

How to calculate the amount of magnification when a DSLR camera is connected to the telescope?

I'm using a 1250mm scope and a Nikon DX format DSLR (D90). A t-adaptor is used to attach the camera to the photo port.

You dived the telescope focal length by the camera focal length, which for 35mm film cameras is 50mm.

For DSLR cameras, its a little less (APS-C format), but 50mm will get you close.

So for your setup, 1250/50 = 25x

http://www.umich.edu/~lowbrows/reflections/2001/ckessler.4.html