Evolt E-500 with mirror telephoto

I have an Olympus Evolt E-500 with a 500mm mirror telephoto lens, and I can't get the settings right - it looks really dark through the viewfinder, and even with a tripod, I've not managed to get a pic that's remotely decent.
Maybe I bought the wrong lens, but it has to be possible to get something good from this - can anyone suggest some settings I could try?
It's a manual focus (harder to do than I realized!) and it's a fixed F8.
With the additional ring I had to get to make it fit onto my camera, it's apparently now the equivalent of 1000mm, and does have great magnification, I just thought it'd be easier to get decent results from.

Holy moses.
f/8 fixed?

The disgustingly slow f/stop of mirror lenses is usually the top reason why I've avoided them. What are you shooting that requires 1000mm? Even the sports photogs I know rarely carry higher than the 600-800mm mark, and then maybe a 1.4x or 1.5x extender if needed.

You're going to need to crank the ISO perhaps 400 or 800, then slow shutter to compensate for f/8. I'm not saying it wont work, bright sunny day - you've got an ideal long lens.If not, take it down to the absolute lowest ISO you have, crank up the brightness in post-op. Manual focusing takes practice, practice, practice. For something that long (I dont know) I'd want to use a monopod, or as you said - tripod, to have the weight on the support item, hand on the shutter grip, left hand freely moving around the lens.

You've got other lenses right? I wouldnt really keep this one, unless you have a need for 1000mm. Go with a lens that tops out around 300mm or such, shoot in a large size, crop.

My guess is that if you're lens has doubled to 1000mm, you apperture has also doubled and you're now shooting at f/16 instead of f/8. This is going to be very dark when you look through your camera which is going to make manual focus even more difficult. A good sturdy tripod is a must, along with a cable release or some other method of tripping the shutter without touching the camera. The self timer will work for this also. If your camera has mirror lock up, use that too.

Your meter should tell you how you're underexposing. Put the camera in either shutter priority or metered manual and see what the meter says. With modern TTL metering there's no reason for accidental underexposure.

By the way - I'm also curious about what you're shooting with that behemoth. Could be cool. I have a friend who shot the motorcycle races at the Isle of Man with a Nikon 500mm mirror lens. The photos were great - when they were in focus and the shutter speed was adequate.

These lens all have a sweet spot of focus. Get a friend and t-shirt that has decent sized lettering and a football field. On a very bright day (10am-2pm, normally the worst time to take photos) have them start out about 35 yards away and walk away from you five yard at a time. Each five yards take a photo at optimum exposure. If it is a white t-shirt you may have to bracket the images. You will quickly find out where the lens will produce the best and sharpest image.

PJ's post about using the camera's metering is definitly something you should take note of in your testing. I've got a couple of older long lens that don't meter quite like I think they should for some odd optics reason, probably due to an anomaly or optical flaw that causes light to get more concentrated on one area of the TTL metering. Try the narrowest form, like spot or central metering with this lens. The light falloff at the corners on all the mirrors is dreadful and a matrix or average metering can easily produce bad results.

Post some images when you can, always like to see long distance shots.