I gave the outside of scope blur one more thought, as it was presented in the latest news with this WIP screenshot.
I looked down a tube, as if aiming a scope, and I generally see what the idea is. The scope covers up the focus area, while the focus point has a magnified perspective. Both create that rift between the focus area and peripheral area, which is usually not too apparent. A blur effect might not be a bad idea to convey that feel, but there have to be a good compromise.
The picture below is an example. The peripheral effect is there through a vignette around the edges, but does not feel like an artificial overlay that covers the entire outside of the scope. You retain the ability to scan the area at the front outside the scope. The left arm that is stretched out and the weapon parts are at different distances from your eyes, so the weapon blur should look natural, while you can look down on your arm.
I like the idea of it, because I would like to see sights to be implemented in a way that makes them realistic to use, but not too comfortable to look and move around. If you need to keep your scope at a certain point, ready to shoot, but need to keep the area around it in check, you do it, because you can, but if you want to observe the entire area, it would be more comfortable to drop aim, as in real life you'd not force your face to a scope.
With non magnified sights and iron sights, I'd keep that vignette effect, but to a minimum, because the said rift between the optic and outside is less apparent, especially with iron sights, but the idea that observing the area without aiming sights is best should be there, at least to an extent.
This has been a dream of mine since forever.
Usually in games with 3D sights the weapon moves smoothly to/off the centre if you aim/unaim. With sprite sights (Americas Army 2) the sight snaps into/off the view. I actually like that, because if you aim a sight by closing one eye, the sight indeed kind of snaps into view. If a game wants to make it right, than they will have an initial "3D weapon moving to centre" animation, which isn't completed, because by then the shooter closes the other eye and has the sight snapping into view.
That "snapping into view" is an effect I'd like to see with 3D sights. This is how I suggest it:
Let's say there are two camera positions, one for non-aim and one for aim (located slight more to the lower right). Since the character brings the gun higher when you aim, the "aimed camera position" would be located where the sight will be, not where it currently is, of course.
The idea is that if you switch to aim, the "non aim camera" begins to move to the "aim camera", while the character animation will begin to move the weapon straight up. Only both, the weapon and the camera will not move toward each other until they overlap and you aim the weapon, but the moving "non aim camera" will fade out and the "aim camera" will fade in (like morphing two pictures). The effect will make it look as if like you close the left eye and suddenly the sights blend in, that are already in front of your right eye.
The extent of this effect would vary depending on the sight type. Traditional iron sights and scopes would have most of this. Holo sights, that can be aimed with both eyes open, would have less of it, not to look like you really close your left eye. Pistols would also have less of it, due to them being held further stretched out.
I doubt I could do anything like this in an INS mod, but perhaps you guys could experiment with something like this?