In article <4fsgc7$pt5@news.uit.no>, paalj@ibg.uit.no says...
>jose@gmgate.vircom.com (Jos=E9 Lopez) wrote:
>>The most powerful lens I currently own is a 75mm-300mm zoom, I'm >>looking for something a lot more powerful. (...)
>>Is it possible to get a mirror 1000mm or more lens for $1000?

>Have you ever tried a 1000mm lens? Not to mention one with maximum
>apperture of 11? Takeing sharp picture with such a lens is an art.
>You need a tripod that is more expensive than the lens. Hell, even
>the most sturdy Gitzo tripod isn't sturdy enough for such a lens
>(I know, I have both). You need two tripods. In addition you need (..) >Paal

I agree. In photography there is this unfortunate truth: any lens
that even begins to be long enough to be a real telephoto is already
too long to use practically. The telephoto "effect" and usefulness
starts around 500mm, but at that focal-length, atmospheric effects
limit photography to only a few hundred feet, or to the few really
clear days when the air is also still, or to big sun or moon photos.
Cornell University sits tantalizingly arrayed on the hillside and
hilltop about 2 miles from my house which is on the opposite hillside.
When the moon or sun rise behind the bell tower, or when the sunset
is particularly spectacular, I try to shoot it with 600, 700, and
1000mm lenses, but rarely succeed in getting sharp photos. Even when
the air is clear enough, heat rising from the town in the valley
between the hills shivvers the air enough to spoil long-lens photos.
Hope This Helps