Nikon d3100 & nikkor 18-200mm good for indoor equine sports?

I'm moving on from my Pentax X90, which is bad for indoor sports and general horse shots.
I'm completely new to photography and have no idea which camera or lens is good for indoor/outdoor and general shots of horses.
For sport you use high ISO (am I correct here?)

I've picked up that the nikon d3100 and nikkor 18-200 go well together. But i've also read that a 'tele lens' is fantastic for indoor? And i've looked and there incredibly pricey.
any help?

Yes you are right about the D3100 and 18-200 mm being a good combination, but for shooting outdoors if you are shooting action or sports.

Shooting indoors requires a much faster lens at 200 mm or 300 mm like a f/2.8 (the 18-55 mm lens is f/5.6 at 200 mm)

By the time you jack the ISO up to 3200 ISO, you may still not be able to shoot at 1/500th second required to shoot any kind of action.

It is not the camera, nor is it the lens that is the problem. You just do not have the right tools for shooting any indoors equine photography.

Outdoors those two in combination are capable of shooting brilliant images.

Shooting indoors is one thing, but shooting action indoor is a totally different game. Moving things need to be shot with decent shutter speeds, with good technique you could get away with speeds as slow as 1/200, but having the option to 1/500 would be useful.

The 18-200mm f3.5-5.6 VR lens the best lens in it's class, but it's designed for general purpose, primarily outdoor use.It'll probably be okay for press and events indoors, either with a flashgun or slow moving objects.

Also if you thought the 18-200mm was pricey, you haven't seen the gear you need. At the very least you'll be looking at a 70-200mm f2.8 with stabiliser, which will be between £1000-1600, but the pros will be packing a 200mm f2 which costs in the region of £4000. This will then be connected to something like a Canon 1D mkIV or 1D X or Nikon D3 or D4 (which is another £2000-5000).

Anyway, to do this on a budget, I suggest that you get a Nikon D300S with the MB-D10 grip and EN-EL4A battery, or a Canon 7D (will do 8FPS out of the box). For the lens, you can get away with the AF-S Nikkor 70-200mm f2.8 G ED-IF VR II or the Canon EF 70-200mm f2.8 L USM IS II, or with the Canon system, the 135mm f2L USM is a really useful lens too, though you'll need a general purpose lens to go with the 135mm.

You also need to be away, none of these cameras will give you the results you want straight out of the box. You need to learn how to squeeze the most from them. This means understanding exposure, and autofocus especially being able to handle the camera in the semi-manual and fully manual modes.

Personally, my preferred setup would be:

- Canon EOS 7D (£400-700, a 1D mark III would be better at £900 but harder to use without experience)
- Canon EF 135mm f2L USM (£500-600)
- Canon EF-S 17-85mm f4-5.6 IS USM (£200 used)

Any less and you'll be struggling to get the shots you want.