Regarding aperture/shutter speed:
Originally posted by flickr G15 Group:
Just to add further to your explanation, compact cameras like the G15 use a combination of electronic and mechanical shutters.
If I remember correctly, the electronic sensor based shutter is inferior to the mechanical shutter. Ghosting and blurring artifacts are recorded since the pixels are accumulating photons (light) and once full, cannot store any further photons; therefore it has to stream off the output data to the camera's digital signal processor in real time.
The mechanical leaf shutter is represented by the lens' iris or diaphragm. It serves a dual purpose; exposing the sensor to light and stopping down the lens to the desired aperture at the same time. Maximum sensor sensitivity is achieved as the sensor only streams the data after the brief moment it's exposed to light.
Since compact cameras don't have independent mechanisms for controlling the shutter speed and the aperture (unlike dSLRs), there's a tradeoff between max aperture and max shutter speed.
Unlike dSLRs, compacts cannot give you the fastest shutter speed and max aperture at the same time. It's not mechanically possible for the iris to open up to f/1.8 (as in the G15) while forcing it to close at 1/4000th of a second. This is why in Manual mode the shutter speed has to drop as the lens aperture is opened up. |
//www.flickr.com/groups/powershotg15/discuss/72157631883749301/ |
