Intro to Prime Lenses and Bulb Exposures

Canal
Amsterdam, Holland

Canon Rebel XT
Focal Length 55
Aperture 22
Shutter 30 sec.
ISO 1600

Don't ever let anyone tell you that you need a high end camera to shoot great pictures.  This was shot with an entry level Canon DSLR.

For this photo however there are a few things that I would have done differently if I had the opportunity.  First, I would have used a prime lens.  Canon makes an excellent 50mm lens in it's entry level EOS lens series, as well as in it's upper end line of lenses - the L series.  Truthfully the difference isn't all that noticeable between Canon's higher end and entry level lenses.  This was shot with the lens that came with the camera - an 18-55mm.

Since there is fewer components and pieces of glass within prime lenses you will be able to get a much sharper image.  The disadvantage is that prime lenses are set at a fixed focal length, so you won't be able to zoom in or out.  Another advantage of a prime lens is that you are often able to shoot at lower apertures.  These are often referred to as "fast" lenses because you are able to use a faster shutter than other lenses.  Let's say you set your aperture to 4 (my maximum possible aperture for my 24-105 L) which had a corresponding shutter of 1/120.  With a prime lens (with a maximum aperture of 1.2), if you were to set the aperture to 4, you would be able to shoot at a much faster shutter - say around 1/250.

The other thing that I would have done differently would have been to use a shutter release switch.  With most Canon EOS models you are only able to set the shutter to a maximum of 30 sec.  Typically this is enough, unless it is especially dark as this scene was.  A shutter release switch would allow me to manually hold the shutter open for an indefinite amount of time.

For me, since I was determined to keep the aperture at 22, I was forced to bump up the ISO to a level that was higher than I had wanted.  This resulted in unwanted grain in the photo.  The benefit of using smaller (larger numbered) apertures is that you are able to obtain starburst patterns around lighting which can be quite appealing.  Conversely, if you are using larger (smaller numbered) apertures you will let more light into the scene which will look better if you are trying to add more light to the foreground.  However, you may get orb looking objects surrounding the light sources.  I would recommend shooting in black and white if you are planning on using larger apertures at night - although it's personal preference at that point.  Another advantage of using larger apertures is that with so much more light coming in you will rarely need to use a manual shutter release to hold the shutter open longer than 30 seconds, and you will also be able to keep the ISO at a manageable rate.