Zeev's Turnips Patch-No Politics (ZEEV)

[James T Kirk]

>>if you are using telescopic viewers, no glasses at all (apart of astigmatism correction?) would do<<

Just for informational purposes, astigmatism correction with a scope is somewhat dependent on the magnification used. High magnifcation results in the cone of light exiting the eyepiece to be very narrow. Low magnification results in a much wider "exit pupil". So, astigmatism would show up much more in a low power scope because your whole eye is being used, much the way your wide open pupil at night shows up all the defects in your eyes. Much more so than the narrow pupil you get in bright sunlight.

So, to sum up, whether you would need correction for astigmatism with a scope would depend on the severity of the astigmatism and the size of the exiting pupil of light from the scope (higher power creating smaller exit pupil and fewer problems). Mild astigmatism and high power scope would not need corrective lenses.

Another option for people with severe astigmatism (more expensive) would be to have the astigmatism correction built into the scope. One small lense before the eyepiece.