As far as Canon lenses go, the 50mm f/1.8 is probably the cheapest, smallest and lightest (130gr) lens in the Canon range. However, that doesn't mean it's not worth looking at!

It's a prime lens (ie, fixed focal length lens), with a maximum aperture of f/1.8. This makes it a great lens for low light situations, due to the large amount of light it'll let in at its maximum aperture.

This large aperture also provides a very short depth-of-field, which is great for portraits, allowing you to have the subject in focus, but the background blurred.



Here's some photos of the Canon EF 50mm f/1.8 II lens.

side view

front view

The specifications of the EF 50mm f/1.8 II lens are as follows:

focal length	50mm
mount	Canon EF
maximum aperture	f/1.8
minimum aperture	f/22
minimum focus	45 cm
weight	130 grams
dimensions	68.2mm x 41mm (width x length)
filter size	52 mm
aperture blades	5
optics	6 elements in 5 groups

Note that the Canon EF 50mm f/1.8 II has a plastic mount, while the older mark I version had a metal mount, and also had a distance window to indicate the focus distance.
However, the plastic mount on the mark II in no way detracts from the operation of the lens.



On a crop body (APS-C sized sensor), the 50mm focal length is equivalent to 80mm, which is a useful length, and works well for portraits.

The large aperture of this lens makes it possible to take photos hand-held in low light that are just not possible with slower lenses.

The micro motor focus is noisier than any USM lens, and in low light, it can struggle to focus, hunting backwards and forwards several times. Due to the micro motor focus, this lens does not support full-time focussing, so if you want to use manual focus, you need to move the AF/MF switch to MF first, as you risk damaging the focus mechanism if you try to manually focus while it's set to AF.

Manual focussing with this lens can be challenging, because of the small focus ring, and because the focus mechanism isn't all that smooth. While some people have reported the AF/MF switch to be "sticky" and difficult to move, I haven't had any issues with it.

Many people initially complain about soft photos when using this lens for the first time, but that's typically because at large apertures (ie, f/1.8), the depth of field is so short, softness will result if the focus is even marginally off.

Most copies of this lens are a little soft at the maximum aperture of f/1.8, but are typically very sharp when stopped down to f/2 or f/2.5.

The front element of the lens does not rotate when focusing, which is useful if using a circular polarising filter or if you have a lens hood attached.



While the build quality of the Canon 50mm f/1.8 lens isn't the best, the image quality far exceeds what you would expect for a lens of this price.
Given it's small size, and cheap price, I'd recommend that anyone with a Canon DSLR go out and buy one of these great lenses.

Because of it's great value for money, it's often referred to as the "nifty fifty", "thrifty fifty" or "plastic fantastic".



The Canon EF 50mm f/1.8 II lens can be picked up brand new for approx AUD$139 or USD$115.

If you've got more money to burn, there are some more expensive and faster variations of the Canon 50mm lens available:

• Canon EF 50mm f/1.4 USM lens (approx AUD$600 or USD$400)
  
• Canon EF 50mm f/1.2L USM lens (approx AUD$2274 or USD$1450)

Here are some sample photos taken with the Canon 50mm f/1.8 II lens:

"Samantha"

Canon EF 50mm f/1.8 lens at f/1.8

"Autumn Leaves"

Canon EF 50mm f/1.8 lens at f/2.8

"Nicholas"

Canon EF 50mm f/1.8 lens at f/4

"Adelaide at night"

Canon EF 50mm f/1.8 lens at f/8 for 20 seconds

Update (20 September 2009): added "Adelaide at night" photo.