lets compare the zillions of lense out there

[WesternGuy]

so i have another question:

if I see that Canon, Tamron, and Sigma all sell a zoom lens of similar zoom range, why on earth should I buy the most expensive (Canon) version? Do I really care about the pretty red circle on the end of the lens? Does it really hurt my picture quality to buy a second hand Tamron lens?

A lot depends on the type of camera that you are putting the lens on and the resolution of its sensor. If we knew that then we might be able to give you a more specific answer. Anyway, my 0.02 ¢ FWIW . A lot of people use 3rd party lenses (Sigma, Tamron, etc.) and are quite happy with the results they get, whereas others use only their camera maker's lenses. The only thing you have to watch out for on any lens is the quality of the images that you get with it - if you are happy with them then who is going to say what lenses you should buy or not. This is true whether it is a Canon ($$$) lens or a 3rd party lens. I think that most will agree that there are some excellent 3rd party lenses out there and there are also some that are not so good. Same thing is probably true of the big names like Canon, Nikon, etc.

Those with the red ring around the end are another story and they are expensive. If you are just starting out, then you probably don't want, or need, one of these. It is my understanding that they are aimed at professionals, or serious amateurs, using a 1D or a 5D camera (not that they cannot be used on other Canon cameras)

Basically, like the rest of us, you have to do some homework and find postings where people have commented on how good, or bad, a particular lens is . Followup on some of the sites posted here. Once you have decided, then see if you can rent the lens for a weekend or a week and try it out. If it gives you the images you are happy with, then that is all that matters and you probably want to purchase it. Alternatively, find someone who has the lens you are interested in and see what image quality they get with it. Maybe they might even let you try it out.

Let us know a little more about what you are looking for, e.g., zoom telephoto, basic macro, etc., and maybe we can be more specific about lenses to look at. HTH

Cheers,

WesternGuy