I have a 20year old 80-200mm lens, can it be put on the new digital camera or is there an equivalent digital?

It will depend. There are generally two questions: can it be mounted on your camera, and which of the current camera functions will it support?

Nikon's F mount, Canon's EF and the Pentax K mount have all been in use for longer than 20 years, since 1959, 1986 and 1976 respectively. However, for both Nikon and Pentax, there are several generations of technology supported by the same mount, and there are often camera functions not supported by the older lenses even though they can be mounted.

I don't have detailed information about other makers, such as Olympus, Minolta, etc.

Remember that if the DSLR is not using a FX or full frame sensor, the lens will have a crop factor, typically in the range of 1.5 to 1.7. So your 80-200mm will behave as a 120-300mm or slightly greater.

better check with the manufacturer.

If this is the Canon EF 80-200mm f/2.8L (black) then you hit paydirt. This is a classic amazing lens a.k.a "The Magic Drain Pipe" it looks like a drain pipe but it takes phenomenal pics.

If this is a Canon FD 80-200mm f/4 then you are outta luck. You can get it to work in MF mode but you need an adapter.

It depends on which camera the lens was made for.

We need to know what type of camera the lens was made for! If it is a Pentax I know personally that it will work a new Pentax DSLR. Unless it is a screwmount lens it will have all it's functions available as it did when it was new.

I shoot Pentax and use mostly the older lenses (they're legendary) and I know first hand that they work with the new cameras as I have a K10D which was released less than a year ago.

As for Nikon I'm not that sure about whether it will work or not. And I do know that some old Canon lenses won't work on the new DSLR's.

F-stop

I was able to buy an adapter to mount my 80-200mm 2.8 lens on my DSLR. That won't help you though, because you don't know what camera or lens I was using.