The school-bus-sized observatory launched on April 24, 1990 and overcame early setbacks to become one of the most ...

Let's turn the sun into a telescope. In fact, we don't have to do any work—we just have to be in the right spot.

Testers 1 and 3 had no idea whether they were trying on, for example, a $19 pair of glasses or a $145 pair. Even though frames cost a pretty penny, it’s usually the lenses that most affect the ...

There are some design variations including using a concave-shaped element that ... achievable with a mirror telephoto is a classic example – the Minolta RF Rokkor 250mm f/5.6 which is a MD mount lens.

Light is initially reflected off the primary mirror at the back of the lens onto the much smaller secondary mirror at the front of the lens and then refractive elements finish the job. There are some ...

That measurement gives you an idea of the lens’s field of view and thus the magnification of the scene. Higher numbers give you a narrower field of view and more magnification; for example ...

While this lens is built for full-frame sensors, Zhong Yi Optics states that it also performs excellently with medium-format sensors, without causing vignetting (Image credit: Zhong Yi Optics) More ...

Cataracts are cloudy areas in the lens of the eye. They are common as you age. According to the National Eye Institute, more than half of adults in the United States over the age of 80 have ...

The screen can curve into many forms—concave, convex ... ahead of current bendable screens from major tech companies. For example, some new OLED monitors from LG and Samsung still use motors ...