User: The greenhouse effect is a result of A. absorption and radiation of energy in the hydrosphere. B. consumption of fruits and vegetables that produce a biofuel. C. absorption and radiation of energy in the atmosphere.
A principal focus or focal point is a special focus: 1  For a lens, or a spherical or parabolic mirror, it is a point onto which collimated light parallel to the axis is focused. Since light can pass through a lens in either direction, a lens has two focal pointsâone on each side.
Focal Point is everything that matters in your photo, that's my opinion of course. You should be smart where is the most important place in your photo or what is the most important element in your photo and make sure it's greatly in focus. If I would share a sample of my work in which the focal point was really essential, it's this one: