Question: F-numbers and shutter speeds List the common f-numbers and shutter speeds that your camera provides. On older model SLRs, they are visible on the lens and shutter speed dials. On newer cameras, you have to look at the electronic viewfinder (or LCD screen/indicator) as you manually adjust exposures.

1. Do these form geometric progressions; if so, what are the ratios? How do these relate to exposure values (EVs)?

2. If your camera has shutter speeds of (1/60) and (1/125), do you think that these two speeds are exactly a factor of two apart or a factor of 125/60 = 2.083 apart?

3. How accurate do you think these numbers are? Can you devise some way to measure exactly how the aperture affects how much light reaches the sensor and what the exact exposure times actually are?