More than likely picking up a heat haze that inferior glass does not or may not.
These often appear to move or shimmer but never noticed at close range.
I have a 6.5x 20x 50mm Whitetail Classic, imported from USA. [At the time I was told by a Guy in Simmonds technical that they were really Whitetail Expeditions and optically excellent value for money but had the wrong finish for that range [due to an ordering cock-up]and hence were sold off within the cheaper Classic range.
Anyway shooting from a very warm dinning room last week into a coldish garden seemed to give a wierd effect, a sort of shimmering as the target went in and out of focus. A bit like the effect of heat-haze on sand ot tarmac.
I put the gun on our custom-made gun bench [20mmx20mm solid stainless steel] so it was totally rigid and I still got the same effect.
I waited till the wife came home and asked her opinion. She said it was a bit hazy, and also saw the same effect so I looked again and was suprised to find that it was now fading in and out of focus much less than before. By now with the door open the room was a bit cooler.
Is this normal? or are there gases in the scope, and if so have they leaked to produce this effect?
Any views on this much appreciated as i obviously can't ask the US supplier for there opinion.
More than likely picking up a heat haze that inferior glass does not or may not.
These often appear to move or shimmer but never noticed at close range.
dont worry about the scope its fine.
it was just picking up the haze caused by the difference in temp from room to outdoors.
The change in refracive index in going from air to a glass prism causes the light to bend. Same with looking at a fish in water it appears to be in a different position than it really is. The refractive index of a gas ie air, depends on temperature so there is a change in refractive index in going from wamr to cold air. Thus light will bend. The shimmering is due to convection currents of the air....I think
Thanks guys for your reassuring help.