Constant aperature zooms: why only Canon?

[GenDEM]

Perhaps I haven't been looking hard enough, but I don't seem to see many other manufacturer making canon-mount zoom lenses that are constant aperature.

Is there a reason for this? Is it super hard to do or something?

[Leigh]

Tokina: 80-200 2.8, 28-70 2.8, 20-35 2.8.

Tamron: 28-105 2.8.

Sigma: 20-40 2.8, 24-70 2.8, 28-70 2.8, 70-200 2.8, 100-300 F4.

Plus Nikon, Minolta, Pentax, etc.

Doesn't seem like a Canon exclusive to me?????

Leigh

[GenDEM]

Ahh, I see I was biased towards finding a 16-35 2.8L replacement, I should have looked harder. Sorry bout that!