|
Zoom binos have more moving elements than fixed magnification binos. Getting all of these elements to remain collimated, along with the focusing mechanism, is very difficult, and expensive. During the day, this isn't a problem, as we are viewing extended objects. At night, stars are point sources of light, and the miscollimation is much more apparent.
Fixed magnification binos too can actually be out of collimation even though a day time examination of the set all appears fine. Again it is for the same reason of extended objects vs point source.
Astronomical binos though usually have the advantage of having a set of collimation set screws under the rubber dressing that covers the prisim casing. This is good, not only to fine tune them if they are just out, but also if the binos get a sharp knock which may shift the prisms, tweeking these set screws will reset the collimation.
My 11X70 binos looked fine when I inspected them instore. At night they were just out. By the time the misalignment finally wore me down the warranty period had expired. I just carefully lift the rubber of the prism casing, marked the original starting point of the collimation screws, and then tweeked them an 1/8 turn one at a time until the collimation was perfect. The right side I tweeked anticlockwise, the left clockwise. If the collimation became worse, it was then just a matter of reversing the rotation of the respective screws. Took all of 2 minutes to do, and I'm happy as Larry. Oh, and this collimation process has to be done at night as a point source of light is necessary (doesn't matter if it is a star cluster as each star is point source).
|