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Sharpness - Bokeh
Foto tutorial (English)
Foto tutorial (Espaņol)
Equipment recommendations US-ES
Flaat for Canon
Flaat for Nikon
Flaat for the BMC
Flaat for NEX-5N
Old Picture Style Tests
550D video lineskip
APS-C vs Full Frame
Badly assembled lenses and image quality
Lens mount compatibility chart
ISO on different cameras
High ISO on the 5D3
DIY: DR test chart
RGBWK Bayer sensors
Notes on DoF-FoV
Notes on crop-DoF-FoV
Custom Cropmarks for Magic Lantern on the Canon 550D
How many megapixels do I want?
How many megapixels can I see?
Quick Monitor Calibration Chart
Shutter speed is a parameter that controls how long light is hitting the sensor. It is usually measured in parts of a second (e.g. 30 means 1/30s, that is, "a thirtieth of a second").
By halving this number, we double the amount of light captured in the image (with a shutter speed of 30 we get twice as much light as with a shutter speed of 60). Just like aperture, most cameras allow you to control shutter speed in thirds of a stop (with three clicks you allow twice as much light in: 60-50-40-30) or half stops (two clicks: 60-45-30).
Defining quantity of light = 1 with 1/250 in a completely arbitrary manner, the following table shows how much light is allowed in with some common shutter speed options:
The problem with increasing the amount of light captured in the image by reducing the shutter speed is that we also increase the probability of getting blurred pictures.
First, because the world moves: if you're taking a picture of a running child, you'll probably need to set your shutter speed at 1/125s or faster.
And second, because the camera moves. This depends on your ability, but a simple rule is as follows:
Keep in mind that with very long lenses this can be a problem: with my 300mm on APS-C, this rule leads me to 1/500s, but given that this lens is really heavy and this makes my camera even more shaky, I have to use at least 1/1000s; even in a sunny day, this means I have to compensate by pushing the other two parameters that control exposure (aperture and ISO); the alternative is to simply use a tripod.
An advantage of modern times: if you're using a lens with optical stabilization (IS, VR, VC, or however the lens maker calls it), you can allow yourself one or two stops slower speed (in my previous example, 1/30s or even 1/15s). This is very useful for landscapes, not so much for children (the stabilizer won't make the kids stand still).