Canon EF-S 17-55mm VS Sigma 17-50mm VS Tamron 17-50mm?

Keith Z Leonard wrote:

You can continue to not know about it then, sorry, but it's true. The ability to render a background completely out of focus is nice, can be done with zooms, and isn't done for all portraits, not even the majority of portraits. Studio portraits are pretty much never taken this way, it's more useful for location shoots and events.

There are even pro portrait photographers out there using crop cameras, all things are possible, regardless of what you read here. You can check out a lot of pro portrait techniques by signing up for photovision or the like. While primes and thin DOF are used by some, they are not dominant, and not necessary. Again, group shots don't play nicely with f1.2, and all lenses perform better stopped down a bit (though the 85L is impressive at f1.2).

Remember that DOF isn't entirely based upon aperture, focal length + aperture + relative distances matter. Even using thin DOF you need to pay attention to the backdrop to achieve the best results. Again, it's a tool to be used not to live by.

I know that DOF is more than just the speed of a lens and not all shots require a thin DOF but I don;t primarily shoot group shoots either. Having the abiliity ti open up to f1.8 at say 85mm on full frame and give you a nice blown out background that adds to your portraits is helpful and a slow 2.8 lens might not be enough not to mention primes are exceptionally better image quality wise than the zooms out on the market until you're willing to spejd $2,000 on the two big Canon L lenses which are the 24-70lII and the 70-200 2.8 IS II.

I shoot primarily environmental portraiture as I find most studio portraits boring and stagnant so having that ability to shoot a longer focal length and shoot wide open at F 1.8 or F2 gives me the ability to make my portraits look 3 dimension and the ability to blow ouit the background due to the longer focal length and wider aperture regardless of subject to background distance whereas a 50mm you need a good amount of space between your subject and backgound and most of these zoom lenses don't even have that nice of a bokeh unless you're getting the Canon 17-55.

I find the zoom lenses very limiting personally when it comes to portraiture  I do like zooms for any kind of event but thats about it, sometimes even then primes are better as they give your photos a unique look if you know how to work them right.