Re: Spotting scope quality vs air temp
GG... there is no formula for it.
Next time when you are out on a mirage prone day, take a black paper and some tape.
Cut a nickel sized hole in the middle of it and tape it to the front of the scope so you can lift it up to compare.
Look at a long range target that is in a boil.
Flip down the paper, and what you will see is a sharper target that is dancing.... nothing can make it stop moving, but the smaller opening will make it clearer.
What is actually happening is a long write, and will bore everyone to death... but a classic demonstration of mirage v aperture is the following - take the 80mm scope, and make a paper mask with four nickel sized holes at 12, 3, 6, and 9 o'clock, out by the edge, but still in the light path.
Take the scope out just after sunset and look west at a bright star - you will see 4 starts dancing independently around each other. That should throw some light on the subject. [img]/ubbthreads/images/graemlins/wink.gif[/img] [img]/ubbthreads/images/graemlins/wink.gif[/img]
Here, kitty kitty kitty.
LRH member #23