As long as the games are in daylight, the 70-300VR will do a nice job. I think, however, that many of the professional games are not during the day? Even so, top level sports - in my personal experience, MLB and NFL - have sufficient TV lighting to make slower lenses viable. I would think that MLS is in the same situation. But anything less than the top ranks won't have that much light, and a slow f/5.6 lens just doesn't survive that. I do a lot of minor league baseball, and even at AAA (or some of the beautiful new A and AA stadiums) the light is just not enough to shoot without an f/2.8 lens and very high ISOs. Also, as noted above, many of the top-level pro organizations have limits on photographic gear. I've never had anyone threaten to confiscate anything, but for example one MLB stadium has a limit of 4" on lenses - that doesn't leave many options. Washington is limited to 8" (and I push it another 2mm to bring in my 70-200). Some don't have much of a restriction at all: I've brought in a 50-500 with a monopod to Oakland.
Of course such considerations don't apply to your kids' games. A few other options for the kids games, which I assume must be during daylight since they're during the summer when daylight doesn't end until awfully late...
- Nikkor 55-300 VR: considerably less expensive than the 70-300, probably nearly as good results, but is DX if you are planning an FX future.
- Tamron 70-300 VC SP, a popular alternative to the Nikkor. I've never used it personally but every other Tamron SP that I've tried has been great. About $450 so quite a nice savings compared to the Nikkor.
Finally, as others noted, 300mm may not be all that you want, particularly for the professional games (noting restrictions as above). In those cases two alternatives suggest themselves:
- the Sigma 150-500/f4-6.3 HSM OS. Very possibly not "affordable" (but I don't remember a definition in this thread), at $1000, but almost twice the focal length. Will get you about as close as anything will short of the Nikkor and Sigma Big Guns at 5-10% of the price. A big step up in weight compared to the xx-300mm lenses, though.
If you find yourself trying to fit within "small lens" restrictions, an out that I have become fond of is an old Tamron SP 500/f8 Reflex. (That's another Tamron SP...) It's not an ideal sports lens as it's a manual focus, and it has all of the things about mirror lenses that we don't like - slow aperture, odd ring-shaped bokeh, etc. But it's 500mm, the optical quality is good, it's about $200 if you can find one - and best of all, it's only 3.8" long, so it surprises almost everyone. Of course, at f/8 you need light...
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!