A good friend of mine is in an apparent competition with me...who can buy the most lenses? Actually, we're both quite active and enthusiastic photographers who appreciate having "good glass", and that appreciation has led to our collaboration of research as we research and invest in our increasing collection of optics. Invariably, the question comes up though...why are there so many different lenses, and aren't there just a couple of lenses that we could get that would do everything? Do we really need all these different lenses??
Those are rhetorical questions of course, and the answer is fairly obvious if you think about photography and the nearly unlimited range of image creation styles and possibilities... There is macro, landscape, still life, portraiture, birding, photojournalism, nature, documentary...etc, and each of these is dramatically different from the others in terms of the optical properties needed to maximize their effect or impact. The question would be similar to painter wondering why they don't make just one kind of paint (watercolor, oil, etc...) or one kind or size of paper to put it on.
My friend was commenting on a photographer's presentation he attended this week at his photography club. She apparently had mentioned that her 17-85mm lens was perfect for her work. I suspect that her skills and portfolio cover a much broader range of styles than what she was presenting, but the point was interesting...for that particular style of work, that lens was all she needed. Much like a photographer that works in a studio taking portrait, it would not be uncommon to hear them talk about the a single lens as their "go-to" lens of choice for portraiture.
So you probably see where I'm going... Different lenses allow you to work across a wider range of photographic interests. And unless you're wanting or trying to specialize in a specific or narrow creative endeavor, you will find that having more lenses opens new doors of possibility for creativity and expression.
I'm looking right now to add a 150-500mm telephoto lens to my arsenal. I currently have a 70-300 but have been wanting more reach. I've been wanting this in the context of some wildlife and bird photography. It would be easy to think that a 150-500 is the right lens to have if you want to get closeups of birds or wild animals. And while that might be true, it certainly is not the ONLY use of a long telephoto--and far from it.
As part of my research on this particular lens, I reviewed set of images on Flickr that were taken exclusively with an extended telephoto lens. And you know what? There were no where near as many animal close up images as I expected (or was initially hoping to see). What impressed me was how many images there were where it was not immediately obvious that telephoto was even used. And by that I mean, there were images where the advantage of telephoto was evident, but it wasn't to give you the pimple-view of a subject. The telephoto lense was used to compress distance or to bring out-of-reach subject into a reasonably composed frame without extreme cropping and image loss. There were shots of a cluster of buildings up against a backdrop of mountains--amazing because it looked like these structures were right at the base of these giant mountains. Using the telephoto lens provided a different point of view.
And that's really the bottom line...different lenses allow you to provide a different point of view. You can shoot a flower with a wide angle lens, a macro lens, a "normal" lens, or even a telephoto lens--each can be an excellent and inspiring image, but each will have a different point of view.
If you have questions or comments, email me at CostaMesaPhotography@gmail.com You can also view my image portfolio at http://costamesaphotography.com/
(Metadata for this image is 1/250 sec @ f/4.0 and ISO 80, focal length 33mm)