Canon EOS FAQs
What exactly does EOS stand for?
Electro-Optical System.
What does EF and EF-S stand for?
Electro-Focus and Short. “Short” in this context means it has a short back-focus and should only be used with bodies with a 1.6x crop factor. This refers to the type of lens mount. Prior to EF and EF-S mounts, there was the FD and FL mount. There’s some history for you.
What do the different coloured rings around the lenses mean?
There are a number of different types of lenses that Canon makes – each aimed at different markets:
Silver
If you see a silver ring around a lens, it means that it’s cheap. This is a lens aimed at the low-end consumer market. The lens feels like a toy and the build is somewhat flimsy (usually plastic). These lenses often come in “enthusiast kits” that bundle a lens and a body together.
Gold
Gold rings on lenses usually indicate that it’s a USM (UltraSonic Motor) lens. The USM technology allows for faster and less noisy auto-focus. It’s stock standard on pretty much all non-cheapskate lenses that Canon has in market right now. Not all USM lenses are created equal as there are two different types of USM – ring and micro. I won’t go into details, but ring is better than micro.
Green
The presence of a green ring around a lens means that it’s a DO (Diffractive Optics) lens. The DO technology allows more substantially lighter and smaller lenses. This is great if you’re traveling and don’t want to lug around fat heavy lenses and want decent image quality. You’ll find these in the long zooms to reduce the weight whilst not incurring significant quality degradation. You’ll also be looking to fork out a large portion of your paycheck.
Currently, all DO lenses also have USM.
Red
The red ring around a lens indicates that it’s an L (Luxury) lens. This are the top-of-the-line lenses that Canon makes and as such, people who take their photography seriously (i.e. those that make a living taking photos) pretty much all use these lenses. Next time you spot pro photogs with Canon gear, you’ll almost be guaranteed to find lenses with red rings around them. These lenses are built to last and are engineered to have superb optical performance. They generally have faster apertures than consumer lenses of similar length, and all current models have USM. Faster apertures mean more glass, and that means heavier to carry.
The current series of L telephoto lenses are all white. Some people say that this is just Canon marketing, making these lenses stand out in a crowd. I think the official explanation is that white lenses reflect heat away from the lens and aids in reducing thermal expansion of the fluorite lens elements.
They all come with a hefty price-tag as well, but at least these guys keep their value much better than the other lenses and so if you ever wish to resell them, they can get you a pretty decent price.
What’s a good camera/lens that you can recommend?
What shots do you plan to take? What’s your budget? There are plenty of factors to consider so go do your research 
Do I want a lens with IS?
That depends on whether you plan to take hand-held shots most of the time. IS (Image Stabilisation) is a mechanism where a group of lens elements can be shifted off the optical axis to counteract camera shake. Whilst this sounds great, note that having IS does not mean you can stop subject motion (get a faster lens). It also drains the battery somewhat (figures seem to range between 10-25%). Oh, and this technology doesn’t come for free. You’ll notice this in the higher price you pay, and a very slight decrease in sharpness.
If you plan to use a tripod most of the time and/or have a relatively fast lens, IS is fairly useless except on telephotos.
What cameras are Canon going to release next?
I can’t tell you what I don’t know, and if I knew, I can’t tell you anyway
Is Canon better than [company] in [area of interest]?
Do your own research It’s all very subjective anyway.
Now, I must emphasise that all this is my own personal opinions and comments. There will inevitably be some people who won’t agree with what I say. That doesn’t mean one of us is wrong, it’s just that a lot of it is subjective.