telrad rigel reticle size vs. sky

All,
Apologies if this has been covered, but a quick scan of the archives didn't help me out.

When looking through a unit-finder like a telrad or rigel, doesn't the "size" of the reticle image change depending on how far your eye is from the window? If so, then how far should you be to the unit for it to approximate, say, the telrad overlay on Sky Atlas 2000?

doug

I don't think the projected reticle size changes with distance. Your eye is focused at infinity, so there's no foreshortening.

Try it yourself. Put the bulls eye onto a star field and move your head foreward and back - the reticle will not change size relative to the stars.

Doug

It will never match the full Telrad overlay, which is 4º in diameter, because the Rigel bullseye is only 2º across. That matches the "middle" ring of the Telrad overlay.

Jim