A related issue is the color rendition of the binocular, which is the accuracy with which the object's colors appear in the image. Most optical systems will have some effect on color balance, perhaps filtering some of the red, or giving the greens a bluish tint. Resolution is the overall sharpness, usually measured at the center of the field. It can be seen by placing an auxiliary scope behind the ocular, and viewing a magnified image of the binocular field. A binocular with superior resolution may not give you a noticeably sharper image than a typical quality glass, but there will be subtle effects on the image, giving higher contrast and seeming to snap into focus.
Collimation is the alignment of the images from the two objective lenses.
New, inexpensive, binoculars can arrive out of collimation, and all cheap models are easily misaligned if they suffer an impact. To test for this, focus on a distant, very small object. Gradually draw your eyes back from the oculars until you are holding them about 6 inches from your eyes, meanwhile retaining the image of the object in the oculars. If the binoculars are misaligned, the images from the right and left eyes will separate and appear as two images. If you can fuse the two images into one while the oculars are held away from the eyes, they are aligned.