focal ratio
Focal ratio, often represented as f-stop (e.g., f/2.8), is a measure of a camera lens's aperture size relative to its focal length. It indicates how much light the lens can gather: a lower f-stop number means a larger opening, allowing more light to hit the camera sensor, which is beneficial in low-light conditions and creates a shallow depth of field for blurred backgrounds. Conversely, a higher f-stop number results in a smaller opening, suitable for bright environments and providing a greater depth of field, keeping more of the scene in focus.
Additional Insights
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Focal ratio, often expressed as "f-stop," relates to how much light a camera or telescope lens lets in. It’s calculated by dividing the lens's focal length by its diameter. A lower f-stop number (like f/2.8) means the lens has a wider opening, allowing more light, ideal for low-light conditions or achieving a shallow depth of field. Conversely, a higher f-stop (like f/16) means a smaller opening, letting in less light, which is suitable for landscapes where more of the scene is in focus. Understanding focal ratio helps in choosing the right settings for different photography situations.