Jonathan B.
Well-known member
henry link said:Jonathan,
Thanks for the suggestion. I've done this too, and did it for the binoculars I tested on this tread. I don't know how wide the tolerance is, but the eye seems to be able to successfully merge images of slightly different magnifications. In this case I tried to place the images of the blue bird box from the two binoculars right next to each other. With both images swimming around I find it hard to make really accurate judgements about relative size. I think another problem is that distortion will effect the apparent size of objects differently depending on how much large the objects are and where they are located in the field. A binocular with barrel distortion will have maximum magnification at the center of the field while a binocular with pincushion distortion will have minimum magnification at the center.
A problem for me with using this technique for judging brightness and color cast is that I often seem to see a slightly brighter image from one eye than the other (usually the more rested eye) and I always see a different color cast, warm on the left and cool on the right.
Henry
Yes, I'm sure this wouldn't work for slight differences in magnification. I can achieve a degree of stability in merging the images by resting the binoculars on a fence rail or table top while viewing, but it is ungainly and requires different size/shape cushions under each.
My eyes also perceive color differently--more red in one eye and more yellow/blue in the other. In comparing color casts I have switched the binoculars from side to side, but it really doesn't tell me much more than looking through each binocular separately.
In any case, a half-power difference is obvious to me when merging images in this manner, and relative brightness is also fairly obvious.