English - Espaņol
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
The third way to increase the amount of light captured in the image is by telling the camera to use a higher ISO sensibility, so the sensor reacts more to the light that it receives.
Most cameras allow you to change this parameter in full stops. Defining quantity of light = 1 with ISO 100 in a completely arbitrary manner, the following table shows how much light is allowed in with some common ISO options:
The problem with increasing the amount of light captured in the image by increasing the ISO is that this amplifies the noise in the image: whereas at ISO 100 or 200 images are usually quite clean, with higher ISO values you'll get progressively more noise, specially in shadows and in plain color areas (like a wall or a night sky). How bad this is will depend on the camera, so do your own tests and evaluate how much you can increase ISO before noise becomes a problem for you.
With my current camera, looking at a 100% crop of the image,
the amount of noise at ISO 100 and ISO 1600 is the following:
But we hardly ever look at pixels one by one. If I first rescale the image
to 1920x1280 and then I do the 100% crop, the difference
is still visible but much smaller:
(if you see no difference between the first two images, you probably have your monitor badly set up; the best option would be to use a monitor calibrator, but if you don't have one at hand you can start with this)
Usually, higher-end cameras, cameras with bigger sensors, and more modern cameras, will allow you to increase ISO to higher levels with smaller noise problems.