Digital cameras 101

[paddlestone]

I have a horse farm, and my students do tons of shows. So I bite the bullet and got myself a very nice Cannon 40D with a mega 70-300 lens. While I have easily figured out how to take a picture with it in sunny outdoor conditions while taking pictures of single horse jumping quickly over a fence, taking pictures of a rider in our barely lit indoor is a bit of a challenge. All the pics I take are either super dark, or very blurry. I tried setting the ISO in a preset setting that allows me to change the iso to 1600, and it doesnt seem to help. I ran into a guy at a horse show who seemed to be taking very bright photos and he said I needed to lower the ISO to 400.... ? Let me give the set up of the place im taking photos of , and hopefully someone here can give me some tips.
The indoor arena is about 200ftX200Ft. I can only stand at the far end to take pics , hence the reason i bought the mega lens. There is some natural lighting, but its fairly dark for picture taking. I want to take pics of a single horse RUNNING and JUMPING, not standing still from a distance.
Please give any hints in VERY elementary  speak as I am NOT a camera wiz and barely know what I am doing!!! I know taking a clear pic from afar in the arena is possible, as the pro photographer at the show has the same camera I do and her pics are nice. And she gets the pics from the same distance I am standing at. Someone please help!

[Mike54]

The "pro" photographer may have the same camera as you but I'm willing to bet she isn't using the same lens. Your lens is, as you indicated, quite adequate for outdoor sunny situations. The problem is the aperture and at the long end (300mm) the most open you can get is 5.6 which may not be enough in poor light situations. You didn't indicate what setting you used. I'm not sure why someone would tell you to "lower" the ISO if your pictures were coming out dark. The higher you go with ISO the more chance you have for noisy (grainy) images but in some cases it may be your only choice to get enough light on the sensor. Start at ISO 400 and set the aperture as low as you can (f4 for 70mm & f5.6 for 300mm). Set the camera to AV mode and see what shutter speed it gives you in your indoor conditions. If it's 1/60 s or better AND you're good at hand holding it may be enough. Personally I couldn't do it. If the speed is indicated at less than 1/60 s bump up the ISO to 800 and see what you get. Once you get past ISO 800 you'll have to decide if the quality is good enough. The best option (if you can afford it) is better glass. In an arena that's 200 x 200 ft. I would think you might be able to get away with a max 200 mm lens. For the option of zoom you might try a 70 - 200 f2.8 which give you a wider aperture. I'd stay away from the IS (image stabilized) version because it's better suited to stationary objects. If you find it out of your price range (it is mine) you might try the 200 mm f2.8 which doesn't have the option of zoom but is at least as sharp and has the bigger aperture. Try the wide open aperture and let us know what your results are.

[paddlestone]

thank you so much for your input.. im going to fool with the settings tomorrow and see what I can come up with. I thought that guy was crazy with the low ISO setting. i dont know much about cameras, but that didnt seem to go with anything I had learned. I was setting the camera at first to the "sports" setting just b/c it took the quick shots outside so I almost always got the shot I wanted. However it slowed down so much, and barely would take a shot a second (it takes about 7 in daylight) So I switched to the TV mode and tried to change my shutter speed, with no luck. I saw the pro uses a flash, however the horses are so far away there is no way its really doing much but adding some fill light maybe. She does have a better lens, so maybe thats what I need to do? Ill try again tomorrow and will let you know my findings! thanks again for your input! it sucks having such a nice camera (after years with a fuji fine pixs camera) and not knowing how to use a darn thing on it, and I swear that manual is written for only professionals b/c I cant understand a word of it!

[Mike54]

I wasn't sure if flash was something that could be used but if so you could always try a "Better Beamer". It's use may be limited to the long end of your lens (300mm) but it could help some and it's less expensive than a new lens.