Kind of ... The boost that a Turbocharger delivers is dependant not only on engine speed, but also on how much fuel you're burning - if you start climbing a hill and put your foot down to maintain speed then more fuel is burnt and the turbo boost increases without any increase in engine speed.

A supercharger, on the other hand, delivers a fixed amount of air per revolution of the engine regardless of how much fuel you're burning - this presents difficulties: It places a hard limit on how much fuel you can burn (because you can only burn as much fuel as you have oxygen to burn it with), this is especially important at high altitudes when you need to force larger volumes into the engine to get the required mass of air for combustion.

There are in 2-stoke diesels (EMD 645, for example) that have supercharged variants for low altitude use, and turbocharged variants for high-altitude/more demanding purposes. However, because 2-stoke engines need forced induction to work* a standard turbo is unsuitable at idle/low power since it wouldn't deliver the intake pressure required for the engine to run at all. To cope with this the turbo is driven from the crankshaft through a clutch that allows it operate (effectively) as a supercharger at low speeds but as full turbo at high speed.

* In case you're wondering: on a small 2-stroke petrol engine such as might be found on a chainsaw or motorcycle, forced induction is achieved by using the crankcase to pressurise the charge - so the charge is sucked into the crankcase through a non-return valve during the compression stroke then pressurised during the power stroke before flowing into the cylinder through the intake port.

Just to add this good explanation...

So if you focus on a specific point, objects closer than that point will blur as they get closer, and similarly objects further away will blur as distance increases.

The range of distances over which you have acceptable focus is known as 'Depth of Field' (or DoF) and it's affected by two factors: 1.> How far away you are focusing (the further away you focus, the larger the DoF) and 2.> The size of the aperture (e.g. iris or a gap in your fingers) through which you're looking (the smaller the aperture, the larger the DoF - this is for the reasons explained by u/waitforthestopsign)

The DoF is not symmetrical - in fact objects closer to you than the focal point quickly blur (but we tend not to notice because these objects are often in our peripheral vision); objects further away than the focal point blur more slowly as distance increases.

A consequence of this is that in very bright light the iris in our eyes contracts to limit the amount of light entering the eye, which has the effect of increasing the DoF and makes it much easier for the lens to focus - this is because it the lens doesn't need to be as accurate, and deficiencies in the lens (e.g. long-sightedness) become less noticeable. The effect is particularly noticeable on objects that are close to us which is one reason why reading in good light can be so much easier that in poor light.