I've got three in my bag at the moment. 17-50 2.8, 70-300 5.6 zoom and the "walk around" 18-270 3-5.6 along with an assorted amount of filters. If anyone has one of those Sigma MONSTERS laying around, not using it...just let me know LOL.

Very nice article, thank you. I only carry 2 lenses as budget is tight, Sigma 18-200 tele OS, and Canon 50mm f1.8. The fast 50mm lens is such a bargain everyone should have one!

I'm no pro, but can recommend a few pieces of glass. I'm in the Canon camp but Nikkor (Nikon) lenses are probably available in similar specs. There are even some good third-party lenses that are also similar and may be some-what cheaper.
17-40mm f/4L - A general purpose quality lens. Provides clear images ideal for daily photography. 50mm f/1.8 - Cheap! Also brilliant (and fun) for low light work. Given the small price you will never regret this buy. 100mm Macro f/2.8 - fantastic portrait lens (just not in confined spaces!), good range for indoor sports (and nature shows like at sea world), good low light performance and of course, macro (rather addictive) photography. This lense also manages my sports photography. WIth the camera set to high resolution it's easy to use digital zoom to get more out of this lens. This means I don't need a longer (bigger zoom) lens.
Another thing to keep in mind - any quality super zoom will cost a lot, be heavy, bulky and unless you are photographing a lot of sports or nature like birds, won't get much use. Most people won't find much benefit from these lenses. Many buy them only to regret the purchase as the money would have been better spent on a quality general-purpose lens.
Happy photographing!

You should say greater or less depth of field compared to...
If composing the same image in the viewfinder, the DOF is the same with all lenses.

Its an awesome article.

Excellent article. I'm new to the craft and art of photography and your article made the daunting task of understanding lenses very digestible and easy to understand. Thank you Simon.

Excellent article, wraps it up very nicely. Keep it up!

Great article thank you.

When choosing lenses, it is important to know what kind of pictures you want to take whether it be portraits, landscapes, action shots, etc. Different lenses have different effects based on their features.

Being new in the world of photography I love articles like yours. To be honest, I bought my lenses fairly fast after I purchased the body.
My configuration:
Canon Rebel 2ti - I love the options, yes there are newer versions but I am good for now
18-55 mm f/3.5-5.6 - Hardly ever use it, although it is a light lens
18-200 mm f/3.5-6.3 (Tamron) - Ideal multi-purpose, but the autofocus could do better. I prefer to focus manually with this one. Once able I might by a Canon 70-300 mm since the autofocus is better
50 mm f/1.8 - Cheap!!!! Awesome pictures. Even I seem to make nice portraits of the kids :)
Reading an article like yours gives me better understanding of the lens and there proper purpose. Thanks for that, because it leads to better pictures.
Kudos!!