Barlow lens and exit pupil size

[Nikodn]

When using a 2X barlow lens does the exit pupil size half when the magnification doubles ?...

[Stu]

Just now, Nikodn said:

When using a 2X barlow lens does the exit pupil size half when the magnification doubles ?...

Yes. A x2 barlow effectively doubles the focal length of your scope. This doubles the magnification and, given that exit pupil is aperture/magnification, the exit pupil halves.

[Nikodn]

Thanks Stu...