Enhanced Vision reflects an individual's ability to perceive things with greater acuity than a normal human being. Often, such an ability lends itself to a wider range of vision-based powers such as telescopic vision, infra red vision and x-ray vision, many of which can be used in conjunction with one another. Most vision-based powers are activated through an act of willpower, and are not an automatic function of a character's physiology (some exceptions apply). Characters such as Superman also have a vision-based power known as Heat Vision, but this is in fact an application of Energy Projection, and has little to do with Superman's enhanced eyesight. Many powers have been referred to by different names, even though they often perform the same function. The Martian Manhunter for example refers to his X-Ray vision as Martian Vision. Ultra Boy of the Legion of Super-Heroes calls his X-Ray vision Penetra-Vision.
X-Ray vision is the ability to see through solid objects. Depending upon an individual's mastery of this power, he or she can adjust the depth of their perception to varying degrees. X-Ray vision can be used to see through material of low mass and volume such as articles of clothing, or it can be used to see through denser materials such as concrete buildings or mountains. X-Ray vision does not enhance an individual's perceptual range however, unless supplemented by another vision-based power, such as Telescopic vision. Since X-Ray vision is a form of ionized radiation, people with this power cannot use it to see through items made of lead.
Characters with telescopic vision can observe objects over remote distances. Their eyesight automatically focuses for distance, and they can see things that are far away with the same degree of clarity that they would if the objects were very close. This power works similarly to a zoom lens on a camera.
The opposite of Telescopic Vision, Microscopic is the ability to perceive items with normal optical clarity that are normally too small to be seen with the naked eye. In some cases, characters with Microscopic Vision can perceive items on the atomic level.
Also known as Night Vision, people with this power can adjust their spectral range so as to be perceive types of light that are normally invisible to normal humans. Characters with animalistic physiology have better night vision through the use of a larger optical aperture, improved retina composition that can detect weaker light over a larger spectral range, more photo efficient optics in the eye, and improved neurological filtering which is more tolerant of noise.
Characters with Thermal Vision can detect radiation in the infrared range of the electromagnetic spectrum. This can often be used to trace patterns of heat, indicating an invisible presence, or high-output energy sources.
One of the more nebulous of vision-based abilities, Ecto-Vision is essentially the ability to perceive the life-force of another living being. Also referred to as soul-vision, individuals with this ability detect an aura around all living things. The intensity of the aura waxes and wanes depending upon the vitality of the target in question. In Mark Waid's 2003 revision of Superman's origin Superman: Birthright, he established that Clark Kent as a youth developed the ability to see the souls of other beings. Whether or not this ability is still considered part of canon continuity is unknown, as he has not used this power since. To date, Superman is the only Kryptonian to ever demonstrate this ability.