Sony a55 vs Nikon D3100

This is a full comparison between the cameras Sony a55 and Nikon D3100. We compare them by looking at the categories you see below.

Sony a55

Nikon D3100

Manufacturing

Sony a55 is manufacturered by Sony but Nikon D3100 is from Nikon. Both Sony and Nikon are well known brands though.

These two camera models were both released 2010.

Camera	Released
Sony a55	2010
Nikon D3100	2010

Type of camera

Sensors / crop factor

These cameras have different sensors. Sony a55 has a "Sony APS-C"-sensor while Nikon D3100 has a "Nikon DX"-sensor, and their difference in sensors will also affect the crop factor and experience focal length. See the table below.

Camera	Focal length, 50mm f/1.8 **
Sony a55	75 mm Sony APS-C sensor Crop factor/focal length multiplier by * 1.5
Nikon D3100	75 mm Nikon DX sensor Crop factor/focal length multiplier by * 1.5

** Experienced focal length when using a lens such as a common "50mm f/1.8"

Learn more about crop factor and focal length multiplier here:
Camera selection can affect the focal length (Sony)
Camera selection can affect the focal length (Nikon)

Resolution

Sony a55 has a 16 MP (Megapixels) resolution while Nikon D3100 has 14,2 MP. If we break down this in more detail this is the data behind the numbers:

Camera	Megapixels
Sony a55	16 MP 16032768 pixels 4912 x 3264
Nikon D3100	14,2 MP 14155776 pixels 4608 x 3072

Sony a55 has a 13 % larger resolution than Nikon D3100. This could give you more details in the picture but also a possibility to crop more in the pictures, afterward while editing the pictures, if needed that is.

ISO range

Both of these cameras offer the exact same ISO range. They both have 100 to 12800.

Camera	ISO Range
Sony a55	100-12800
Nikon D3100	100-12800

Autofocus and lens compatibility

There is a big difference between these two cameras. Sony a55 has a built-in autofocus motor but Nikon D3100 does not. If you want to be able to use autofocus on Nikon D3100 there is a need for having an autofocus motor inside the lens. We really encourage you to look closely at our lens compatibility charts at the links below.

Here is a complete overview of which lenses work with each camera:
Lens compatibility chart for Sony a55
Lens compatibility chart for Nikon D3100

Pictures per second

Depending on what you are shooting the FPS, or frames/pictures per second, can definitely be of interest. Sony a55 can shoot up to 10 pictures per seconds and Nikon D3100 can shoot up to 3 pictures per seconds.

Camera	FPS (Frames per second)
Sony a55	10
Nikon D3100	3

Ability to record movies

It is becoming more and more popular to record movies with digital cameras.

In this case, both Sony a55 and Nikon D3100 can shoot movies.

Weight

The weight of the camera can be an extremely important factor, especially if the camera is about to be used, or carried around, for several hours at a time.

Nikon D3100 weighs 505 gr (equal to 1.11 lb) which is 1% heavier than Sony a55 and its 500 gr (or 1.1 lb).

Camera	Weight
Sony a55	500 gr 1.1 lb
Nikon D3100	505 gr 1.11 lb