Why is it that binoculars, spotting scopes, microscopes, telescopes… all need to be adjusted to be clear at any given distance and rifle scopes thankfully are clear from a few yards out to infinity? Are rifle scopes just a compromise lens wise that we can’t see with our normal vision?

They make binoculars designed with the focus at a fixed distance. I have Minox's BD 7x28 IF.

I should probably use 'em more.

Riflescopes often do have an adjustment. Many fixed are "fixed parallax scopes" that are set for 100-300 yards. If you pay attention, they aren't really that "focused" per se at all distances. It is still a compromise. The more magnification, the more you'll notice it.

Bushnell used to make one of their mid-range binoculars that instead the usual wheel type dial it had a "wing" type dial, a short wing mounted on the where the adjustment wheel would normally be. You focused the adjustable eyepiece for around a 100 yards or so and then to see clearer at far or near distance all you did was press down on the left or right extension. It was a very fast focus system and people who used them really liked them, they were especially good for football game, baseball games, etc. with varying distances and lots of fast action.

I had a Leupold bino with individual focus eyepieces and they were very fast to use, I would adjust the focus for around 100 - 150 yards and items from close to far were in focus well enough be useable. If you wanted to have a clearer picture then you could fine tune them for distance but for general purpose they didn't need it.

drover

Steiner stuff was just about all focus free, for years. This is just me: With binocular vision, it’s hard to see ‘through’ foreground clutter without focusing the lenses beyond it. Monocular vision sees through easier for the single eye. I use Steiner stuff on the water or open fields, and my focusing stuff for picking apart woods.

I once worked for a big gun dealer. You would not believe how many people had no clue that you have to adjust the eyepiece on a rifle scope. Guys would pick up cheap scopes and say, " wow that's more clear than those expensive scopes". I'd then show them how to focus the eyepiece lens.

Never underestimate the stupidity of the average American consumer…..

My eyes are not good at all. But with my cheaper Steiners they are like a 20 yr olds. There are some companies that do offer binos that are adjusted once, but require your eye to do a certain amount of focusing. As my eyes get worse my Steiners require more than an occasional adjustment. All my rifle scopes are adjusted to a point most people would find them usable as set .

Drover, our 10x50 porro prism cabin binoculars have that wing type fast focus and I actually prefer it to the wheel focus on our other porro and roof prism binos. I suppose it was a patented idea from Bushnell, but one that I would have liked on higher end binos.