Best Nikon lens for action shots of horses?

What is the best lens to get for taking action shots of horses mostly in the daytime light and somewhat in lower light? Also with a fairly good zoom, but not MAJORLY expensive.

Right now I have the basic D3100 camera body with a 18-55mm lens. I'm looking to upgrade soon so also what would be a new camera body that would work good for those same specifications but under $1000? Would you stay with a Nikon or go to a Canon, Sigma, etc?

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Both will force you to focus manually though so try to set DOF longer than usual for good measure.

The number one sports telephoto lens is the 70-200mm f/2.8. It works well in both low-light and daytime lighting situations.

However, with such a fast lens, there's a learning curve to using these lenses -mostly in the ability to get the intended subject in focus - which is critical as the DoF at f/2.8 and 200mm is fairly narrow.

For these reasons, I would consider this an advanced lens. You will all but have to learn to autofocus using spot focusing. This is not hard, but it does take some practice and familiarization.

When I bought my first lens of this type, the results were awful, and many blurry photos until I realized what was happening and figured out how to correct it. Once I figured it out, the lens provided some very high quality photos.

The Nikon version of this lens is the Nikon AF-S 70-200mm f/2.8, and costs a whopping $2,400. However there are a few alternatives.

The Nikon AF 80-200mm f/2.8 would be an attractive alternative as it has nearly the same precise optical quality of the first lens, but at half the price ($1,200) - and you can find them used for as little as $500. Unfortunately, it will not autofocus on your camera. Here is one instance when spending $400 more on an advanced Nikon DSLR (D90, D7000, D7100, etc) would have been cost effective.

The next alternative is the Sigma 70-200mm f/2.8, which is still a great lens. It is not quite as sharp as the Nikon AF-S 70-200mm f/2.8, but nearly as sharp, and unless you are a professional that can spend the money on the Nikon, the Sigma's $1,400 price tag is much more appealing. And it will autofocus on your camera.

Finally, consider the Sigma 50-150mm f/2.8. This is more or less the DX (APS cropped camera) version of the 70-200, as when you put it on your D3100, it will have an equivalent focal length of 75~225mm. And it costs about $900, so it might be your best solution.

Whether you stay with Nikon or go with Canon - your lens costs will be about the same (the Sigma lenses are available in either Nikon or Canon mounts).

One thing that needs to be stressed though is that these are big, heavy lenses. You will find them too bulky to use them for an every-day lens, but rather only in sports and action situations. For that reason, you may also want to consider the Nikon AF-S 70-300mm f/4.5~5.6. While still a heavy lens, it is half as heavy as the others, and a much more manageable solution.

Unfortunately though, this is strictly a daylight-only lens, and isn't very good for low-light situations (this lens lets in only 25% of the light the other lenses let in at the maximum focal length).

Your 18-55mm lens should be adequate for daytime shots. If you just need more zoom, the 18-200mm lens would give you that.

Lower light requires a faster lens (bigger aperture, littler number, e.g. F/1.8). Getting that with a zoom can get pricey, very quickly. Getting a prime lens (fixed focal length) is less expensive, but it might not meet your needs. Are you shooting these horses in the pasture, at a rodeo, or an equestrian event? All of the above?

Since you have a Nikon, and are used to the controls, sticking with Nikon would cut down on your learning curve. The Nikon D7000 sells for less than $1000 with a bit longer lens (about 2x) than the one you have:
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