Barlow lens/eye relief?

[casstony]

I've known for a while that balows increase the eye relief of an eyepiece, since when you change the angle of light entering the field lens you change the angle of light exiting the eye lens. Using the same rationale, do eyepieces have different eye relief in scopes of different focal ratios?

I've only used my 35 Panoptic in the f/5 scope so far and the eye relief is perfect, but many complain that it is too long needing an eyeguard extender. I'm wondering if I'll notice longer eye relief in the f/10 sct. Obviously I'll be able to answer my own question eventually but I'm would appreciate any input.

[saberscorpx]

For most systems, where the eyepiece is a small
fraction of the telescope focal length, the ER change is minimal.

A barlow's design, however, dramatically shortens the FL- throwing eye relief way out, especially with longer focal length eyepieces.


SJS

[casstony]

Thanks Stephen.