Does Opteka 500-1000mm High Definition Mirror Telephoto Lens for Canon EOS 1000D, 450D, 400D, 350D, 300D, 50D, 40D, 30D, 20D, 5D, 1D, Digital SLR Cameras work with Canon EOS 500D and is it worth getting it if I'm getting the 18-200mm lens inc. with the camera?

I will be on safari fairly often

OJ: Sorry to seem negative, but I would not advise any Opteka lens. I have only ever had my hands on one and it substantiated all the negative comments I have read or heard about them.

Stick to your 18-200, take huge, fast memory cards and a spare battery with charger so you can always set out on safari with two loaded batteries. Take your pics at the best resolution you can find. (I see that your Canon will create RAW files, but the best JPEG should be fine). Then, back home, you can get on your computer and enlarge the subject in any pics where that subject was a bit far away and keep very good resolution and image quality in the finished item.

You could probably succeed your trip with just the one lens, unless you want to get some real macro done. I've never felt good about enlarged macro shots, but that is purely subjective and is probably objective nonsense

I wouldn't get one. The images I have seen are very soft when you zoom into the image. Depends how critical you are about image softness, I am.

It's a 500mm lens with a 2x Teleconverter to bump it up to 1000mm. The only way to control exposure is ND filters on the back of it. You'll end up using manual focus and at 1000mm you will be at f/16 and will need a REALLY bright day to focus.

Unless you know what you are doing with ISO to up the shutter speed, and ND filters to control exposure, avoid it.

I have a 450D and went on safari with the 18-200mm lens you mention. Got some images of really good quality with it. Personally I wouldn't waste my money on the Opteka.
Enjoy the safari...

I agree with other answers that mirror lenses are not easy to handle. Depending on your budget, you might consider the Canon EF 70-300mm f/4.0-5.6 IS USM Lens. Image stabilizer (IS) can be a blessing if you are going to shoot wildlife, plus, with the 500D the 300mm end becomes a 480mm, which is pretty decent for subjects which are better kept far away. IS can help you with videos (which the 500D can capture at high resolution). Take a couple of spare batteries, a few high capacity memory cards, and enjoy your safari!! Ah, a small tripod (gorillapod-SLR) or a monopod would not hurt either.