EMES 15 is a main sight used in Leopard 2 tanks. It has two vision modes, normal dayvision and a thermal vision mode. Dayvision has a 12x magnification, and the thermal vision has two options: 4x or 12x.
The image from EMES can also be switched to commander's periscope PERI, allowing the commander to observe what the gunner sees. This makes it possible for commander to see thermal image (even though in Leopard 2A5 and 2A6 the commander has his own thermal camera in his periscope). Emes 15 is also connected to the stabilizer, allowing extreme accuracy even when the tank is moving. When stabilizer is on, the cannon follows the sight even in the hardest terrain. With thermal camera and the stabilizer, EMES 15 gives the gunner the ability to engage targets from movement in any terrain, any weather, no matter if it is day or night.
EMES 15 Wikipedia
The dayvision is laser filtered, so incoming laser light does not hurt the gunner's eyes. The field of view exists only in 12x magnification, which cannot be changed, making the field of view rather narrow. It is excellent on long distances, allowing the gunner to see far away targets with great detail. Finding close range targets however is quite challenging. If dirty, the glass of the dayvision (and laser range finder for that matter) can be washed by pushing a button, just like car's windshield.
Thermal camera has two magnification levels, 4x and 12x. The 4x is for finding the target, and 12x for destroying it, just like in dayvision. The image does not adjust itself, so the gunner has to pull the small switch on the control panel to adjust the sharpness if the picture is not adjusted for the right distance. Image can also be adjusted between white and black thermal input, making it easier to detect targets hiding in different temperatures. The thermal camera is excellent for night conditions, making leopard 2 a very dangerous opponent in any time. However, weather conditions may affect the sight, such as fog may reduce visibility quite a lot. Also if the thermal camera protection glass is covered with splattering mud for example, or lots of dirty water, the visibility might reduce to almost nothing, until dried in time or washed by hand. Unlike dayvision, the thermal vision doesn't have a washer which could be used from the inside. The glass protecting the camera is made bulletproof, protecting from small arms.
In case heavier weapons to be used against EMES15, the main sight has armor flaps which can be closed up in front of the glasses of day and thermalvision. This is especially useful if under airstrike etc.
The main sight also has a laser rangefinder, which can detect the range of a target from 200-9990 meters, with 10 meter accuracy. The number can be seen at the lower part of the display when used.
The EMES15 sight and main gun are stabilized both in horizontal and vertical axis by WHA-H22 electrohydraulical stabilizer,the medium error of stabilization is 0,15-0,20 mrad in vertical axis.
EMES15 is connected to the central computer system, which supervises their condition. If any of the equipment failures, or is destroyed, the computer notifies the tank commander with an error text on the screen in front of him.