Final answer:
The two main considerations when designing the objective of an astronomical telescope are collecting faint light and focusing all the light into an image or point.
Step-by-step explanation:
The two main considerations that are kept in mind while designing the objective of an astronomical telescope are collecting faint light and focusing all the light into an image or point.
To study extremely faint objects of interest to astronomers, it is important to collect as much light as possible. This is accomplished by designing the telescope with a large aperture, which refers to the diameter of the light-gathering surface. A larger aperture allows for the collection of more light, enabling astronomers to observe faint objects more effectively.
Additionally, the telescope must be able to focus all the collected light to form a clear image or point. This is achieved through the use of lenses or mirrors that optimize the incoming light rays and direct them towards a focal point. A well-designed objective will ensure that the light is focused precisely and accurately, allowing for detailed observation and analysis.