collimating a refractor; testing it?

I've put togather a widefield refractor (62mm F4.5), but I am having
trouble verifying it's collimation.

Specifically, I can adjust the objective by several degrees, and cannot
see any difference in the performance. I have tried both a 26mm and 4mm
eyepiece (11 and 70 power respectively), I cannot tell the difference
between way off, and close collimation.

Any suggestions as to what I should see with an improperly collimated
refractor vs. a properly collimated one?

Is it perhaps that I am not at sufficient power to see the
imperfections? Or do I need to be in dark skies to see them?

Mark