All optical systems are design around focus. In order to vary magnification and brightness, focus has to be constant. We may compromise magnification for brightness and visa- a- verse, but we can never compromise focus. Therefore, instead of saying that magnification M is inversely proportional to brightness, it is also accurate to say that magnification M is equal to focus divided by brightness B, where focus is a constant D.

M = D/B

Magnification power (M) = focus constant (D) / Brightness (B) Within know optical telescope design, all three factors are integrated. Focus has been the primary factor for rendering a clear image, while magnification and brightness both serves as a secondary factor in the appearance of a focused image. For known optical systems, focus, brightness, and magnification are inseparable. The resolving power is used to sum up the performance of a telescope. It is established by the telescope's ability to imprint details within an image. A picture is the imprint of individual dots that comes together to form a complete picture. Magnifying a picture involve stretching these dots. Light magnification is much different from picture magnification, and magnifies by changing the angle of the received image light.

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