The amount of available light will greatly influence how well the lens works for each situation.
"Best" is such a tricky word. There's "best" as in "I just won the lottery so cost isn't a problem" and then there's "best" as in "I have limited funds and want to know what to get that will not leave me in financial ruin."
Lenses for sports photography aren't cheap. Scott Kelby once did a seminar on the topic in which he explains that what you really need... is a suitecase full of money. This is one area of photography that really pushes the camera to perform and calls for the equipment that can handle the task.
For games such as basketball, the "field" (in this case the indoor basketball court), isn't particuarly large so you don't need a very high focal length lens. But the lighting will be poor (indoor light wont be anywhere close to outdoor daytime photography light). This means consumer-grade lenses with variable focal ratios wont be able to take shots at very high shutter speeds unless you really crank up that ISO setting (and that will introduce a lot of "noise" into the images).
The Canon EF 70-200mm f/2.8L IS USM II is probably "the" lens for indoor basketball shots. It offers a low f/2.8 focal ratio which is available at every focal length (including all the way out to the 200mm end). The f/2.8 focal ratio literally allows the lens to gather 4x more light as compared to an f/5.6 lens.
To freeze action, you'd really like to keep the shutter above 1/500th (faster is better). Typical indoor light might allow an f/5.6 lens to shoot at 1/200th at say ... ISO 1600 (moderate noise but not obnoxious and totally usable). At 1/200th, moving subjects will show motion blur. But with an f/2.8 lens... you could take that same shot at 1/800th... and that would likely nicely freeze the motion.
Outside it's a different story... for games played during the day, it's just a question of what focal length you want. The fields are usually bigger for things like football, soccer, baseball/softball) but if it's daytime you don't need an expensive low-focal ratio lens. But you probably DO want a lens with a nice long zoom range... such as the Canon EF 100-400mm f/4.5-5.6. Large fields benefit from having lenses that can zoom out to 300 or even 400mm.
But if the game is played at night under artificial lights, the lighting usually becomes a problem (for as bright as it seems, it's not nearly as bright as the day). There aren't any good, affordable, low-focal ratio zooms (they would be ludicrously expensive.) This is why you sometimes see sports photographers with two camera bodies... one having a long focal length non-zoom lens (such as a 300mm f/2.8 or 400mm f/2.8) and the other having a shorter low-focal ratio zoom (such as a 70-200mm f/2.8 zoom.)
The gear I've listed above isn't cheap. Can you do sports photography without the expensive gear? Sure you can... but the budget gear is going to struggle to keep up with the high-end gear. Entry-priced zooms usually dont' have especially fast focusing motors and they don't have low-focal ratio optics. This means you'll either have to shoot using slower shutter speeds (which means more images with motion blur) or you'll really have to crank up the ISO (which means more noise in the images). Sports photographers don't invest in those high-end lenses because they're rich and the love to spend the money... they do it because it's the equipment that gets them the results they need ... they have a much higher "keeper" ratio.
If you are younger, have access to the side of the field, and you can keep up with running up and down the sidelines of a football field so you don't need a "long" focal length lens, then that's definitely one way to save money. Canon makes a 70-200mm f/4 version of the lens which is a LOT cheaper than the f/2.8 version. It's only 2x as fast as an f/5.6 lens... whereas the f/2.8 lens if 4x as fast. But it's a LOT cheaper.
As for question #2
Refurbished lenses from the Canon online store are probably the BEST place to find deals. But it's not like new retail lenses in that the lens you might want only comes along from time to time. But if they have the lens, it'll probably be the cheapest way to get a lens that you can absolutely trust will be in just as good condition as a "new" lens.
Next up are the "used" departments at the online stores like B&H Photo, Adorama, or KEH.com. But this is like buying a used car from a dealer rather than from a private seller. The dealer needs to stay in business, account for their overhead costs, and they want to make a profit. So they try to buy the used gear for a llittle less than private party value... and they try to sell it for a bit above private party value. So you'll pay a little more. But you get some piece-of-mind.
Those sellers know camera gear. They know how to honestly evaluate it's condition and appraise it's value. They always list a "grade" or condition of the lens. So if they say a lens is in "like new" condition or in "excellent" condition, first... they explain what that means ("excellent" might mean it's not so new that you wont find the slightest sign of wear, but the wear would be minimal) ... you do NOT have to worry that when the product shows up it will look like someone wrapped a chain around it and drove down a gravel road with it dragging behind. It will, in fact, be in the condition they advertise (they protect their repuation by giving very honest assessment of the quality.) They will also tell you honest when a lens is merely in fair or poor condition... or even when the product doesn't work at all and should only be used to salvage repair parts out of it.
There are also options such as Craigslit or Ebay. These are a bit risky because you don't quite know why the seller is unloading the gear (is it really because they no longer need it... or is it because it has a problem and they aren't tell you). The other huge risk is that often these sellers are not experts and if there's a problem, they may not even know it. Also, do YOU know enough about how to evaluate the function of a lens to make sure it is in working condition.
I would never buy a lens from a private seller I did not know unless I had the opportunity to inspect it and test it myself. This means Craigslist might be ok if I were buying from a local seller and we could agree to meet somewhere safe where I can bring a camera body along to test the lens. With eBay you usually aren't local to the seller.
You'd want to evalute that there is no obvious physical damage. You would want to evalute that the lens if free of any optical damage (including issues such as fungus/mold that can sometimes grow on the internal optics if the lens was stored in humid conditions). You'd want to know that the the lens zooms throughout the entire zoom range without anything sticking. You'd similarly want to know that the focus operates throughout the entire range without any issues. You'd also want to make sure the aperture blades can operate through the entire range without any problems.
And then you'd also want to make sure things aren't loose on the lens and that focus responds. I'd want to know that the lens doesn't have inconsistent focus or front/back focus issues. That's a bit trickier to test without some knowledge (a test target makes it easier.)
When you buy a lens from a commerical seller, this has been done for you. You pay more, but at least you know what you're getting.
Tim Campbell
5D III, 5D IV, 60Da
