focal length and lenses

[Marko]

Not always; it will generally be more expensive because of the optical 'tricks' required to produce a fixed aperture in a zoom lens, but a 'Brand X' fixer aperture zoom may well be of poorer optical quality than it's name brand variable aperture cousin.

In the case of the example in your post however, yes, it would probably be safe to say that the fixed aperture version is a better lens overall than the variable one.

Although what tirediron says is true, you'll notice that most pros (pros that make the majority of their income through photography) prefer fixed aperture lenses.

[tegan]

Yes, I must admit that I prefer 2.8 fixed lenses and have seldom bought anything slower. However when you get to 300mm and beyond size and weight of the lens becomes important for getting the shot or not. When it comes to hand holding a 4.5 versus needing a tripod for the weight of a 2.8, then the hand held 4.5 lens wins out for me.

Tegan

[PKMax]

although it was spam that brought this thread to my attention, I'm kinda glad it did heh. I wasn't aware of the fixed aperture zoom lenses.. it makes sense and now understand why them "pro" lenses are so frigging big lol.

I'd notice my lenses stopped down when zoomed in, and hadn't actually thought about it other than thinking, wow, that's annoying.. I'd not actually considered the fact that it would lose light as it was zoomed in more.