I'll need to add a couple of pictures to this post to illustrate, but I just received a lens I purchased on eBay. It's a well-used, manual-focus Vivitar 70-150 "Macro" zoom. I put Macro in quotes because it doesn't appear that this lens gets anywhere near the range of true macro 1:1 magnification. The closest focus distance is a couple of feet.
It's kind of an interesting challenge using a manual lens on the d50. Obviously, the lens is manual focus, but apparently because the d50 also lacks some mechanical linkage to read aperture information, the camera can't set the aperture either, so only the fully Manual mode really works.
So, I end up setting the aperture on the lens, the shutter speed with the camera, and figuring the exposure by taking a test shot and adjusting based on what the histogram shows. I got a couple of decent pictures of Jeremy the Attack Cockatoo before he got bored and tried to eat me.
It appears that this lens, at closest focus, gives about a 19cm wide field of view, as opposed to the 17cm I get with the 18-55 lens. Not exactly a "macro" zoom. I wonder if the fact that the lens rattles when I shake it has anything to do with that? Maybe there's supposed to be some additional extension at the end of the range, or something? I may just take it apart and see what I can do.