Originally Posted by dhazeghi
... Moreover, almost all the better lenses are primes, and the bang for the buck on those is quite poor compared to zooms (usually you need 2 or 3 primes to replace a single zoom).
I would venture here to make the case both for primes, and for purchasing the best "glass" one can afford. Be forewarned, this response to DH is long and some will find it wearisome
. Readers are forgiven if they bypass this response entirely, and it is to be expected that many will disagree with my reasoning.
It being conceded that multiple primes by definition are needed to replace a single zoom, sometimes having the extra sharpness/resolution an excellent prime can offer allows one to crop and enlarge the photograph and maintain print quality. It is, of course, a truism that zoom lenses offer the ability to "crop within the camera" at the moment the photograph is made; however other than for fast moving subjects, such as a basketball player making a sudden move, there is generally sufficient time to mount a different lens if required.
There is little time during a sports event to change lenses; one either carries multiple bodies with different lenses, mounts a zoom lens, or both. A fast breaking power forward does not pause to allow the photographer to swap out the 90mm lens for a 200mm lens to catch the shot at the other end of the court.
However while making street photos or vacation photos or landscape photos I would argue that one generally knows the focal length needed before the shoot begins and that if a change is needed there is generally time to make the swap. As noted above, an excellent prime lens allows one to crop an image during post processing without undue loss of quality, so making a lens change is not required as often as one might assume. Prime lenses are, in general, both less expensive and lighter than zooms, and are certainly less complicated optically which means that fewer compromises must be made in engineering.
For indoor sports with typical gymnasium lighting my "zoom" lens of choice is the Nikon 70-200 2.8. (When shooting two bodies the second body would be equipped with the Nikon 24-70 2.8).
The price of that 70-200 zoom lens (nearly $2000 U.S. when purchased, currently $2400 U.S.) would easily have covered the purchase of a number of good prime lenses.
For example, the 24-70 Nikon 2.8, also near the $2000 U.S. mark, can be replaced with the Nikon 24,35,50, and 60mm prime lenses for about $1100.
The weight factor is another consideration - the "holy trinity" of Nikon zoom lenses (12-24 2.8, 24-70 2.8, 70-200 2.8) cost in aggregate @ $6300 U.S. and weigh 7.5 pounds.
One can purchase a number of lighter, optically acceptable prime lenses that will cover the 12-200mm range for well under $6300 U.S..
So the "bang for the buck" under those
conditions goes to, I think, the prime lenses. The only argument that I can make for using a zoom lens is that one has no time to change lenses between shots, and that the focal lengths required are so far stretched that cropping is out of the question.
However a preference for prime lenses may entail higher expenditures depending on the specific lens, the inconvenience of carrying and changing lenses is assured, the chances of getting dust on the sensor are increased, and the possibility that the "wrong" lens will be on the camera at the decisive moment is constantly present.
As for quality, both prime and zoom lenses have their place, but one needs to consider the capabilities of the camera body versus the capabilities of the lens. For instance, the inexpensive ($125) 70-300 Nikon DX lens can successfully be used on a Nikon D70 body. However using that same lens on a Nikon D300, with its better sensor, will quickly show the limitations of that lens. The excellent Nikon 50mm 1.8 prime (also $125) works equally well on the D70, the D300, and can be mounted on the full frame D700 and still return excellent results.
That's the argument that brought me to the conclusion that one should purchase the best lens one can afford - that better lenses may be able to successfully make the transition to a newer, more capable body when the time comes. If one buys inferior "glass" one may find that it cannot be used successfully on more capable bodies in the future, requiring one to repurchase the lens in better quality.
This is, I think, unique to the digital age. Having made photographs using 35mm slides and film for years, I do not ever recall having to discard a lens because the resolution of a new film was so great that it fatally showed the limitations of the lens. I really enjoyed using the Nikon 70-300 el cheapo zoom at the local zoo - but it simply fails to perform on the newer camera bodies.
Buying excellent lenses is, to me, akin to shoot "RAW" - I get the best possible collection of data. While I may have no need for the amount of information captured today, in the future there may be a need or an opportunity to use every possible pixel. Ten years ago a commercial lab printed my 8x10's. Today I do it routinely in my home office. In a year, or ten years, I may want to revisit some of my photographs and I consider it wise to capture the best information I can (given the limitations of the format in which I shoot, M4/3 cannot be expected to capture as much data as a full frame camera sensor). Who knows what future technologies will be able to provide?
So I would argue that the "bang for the buck" still resides with primes (fast moving venues excepted) and that purchasing better lenses is, in the long run, fiscally responsible. (Please note that they are not a better "investment"; very darned few pieces of photography gear turn out to be "investments". Rather, photography gear is an expense and it is unlikely that one will see a full return of ones cash outlay when the gear is traded in or sold).
Just my two cents. Now, having read through this missive please feel free to disagree or, better yet, get up from the monitor, go outside, and play.