We consider a lower weight better because lighter devices are more comfortable to carry. A lower weight is also an advantage for home appliances, as it makes transportation easier, and for many other types of products.
2.has an optical viewfinder
An optical viewfinder (or OVF) allows the photographer to compose a shot while seeing exactly what the lens will capture. OVFs have no time lag and require no power - as opposed to electronic viewfinders, which can drain battery life. OVFs are also better in low light situations.
A hot shoe can be used to attach an external flash, as well as light meters, viewfinders, rangefinders and other attachments.
Resolution is an essential indicator of a screen's image quality, representing the maximum amount of pixels that can be shown on the screen. The resolution is given as a compound value, comprised of horizontal and vertical pixels.
Pixel density is a measurement of a screen's resolution, expressed as the number of pixels per inch (PPI) on the screen. A higher pixel density translates into more clarity and sharpness for the images rendered on the screen, thus improving the quality of the viewing experience.
A system camera has many interchangeable components such as lenses, flashes, and other accessories. System cameras offer greater flexibility than compact cameras.