What is the longest zoom lens you can use on a 35mm camera?

That all depends on how deep your pockets are. The longest lens I could afford was a 300mm lens, but they have lens that are 500mm and longer. Anything longer than 300mm will almost always require a tripod because camera shake become more amplified the longer the zoom is.

The longest one you can find.

I have a 350mm but you can get way bigger. They are really expensive when they get bigger than 350.

iv seen ones that you have to put on a tripod. like the lens.

i cant find a link to the lens but this link might help.

150mm lens

the longest that i've seen advertised is 1200mm, but it was huge and outrageously expensive...

for most folks, 300mm is about the longest you'll see. at pro sports games, you might see 600mm.

I read somewhere that there was a zoom that went from 360-1200mm f/11 and the maximum aperture of f/5.6 made it awfully dark to focus and subject that were 200-300 were not easy to focus on. You can only imagine that a lens with that focal length would pose other focus problems; for example, focusing on a cat's nose would make the cat's ears come out out of focus because of the very limited (narrow) depth of field! Also, the only way to use such a lens would be with an extremely sturdy tripod because of the extreme camera shake involved with such a lens.

Most pro sports photogs use a 600mm lens (along with another camera equipped with a 300mm for closer shots). I suspect that some wildlife have used the 600mm with a 1.4 Extender, making said lens 840mm. That would certainly defeat the purpose of speed on the lens (a fast or wide aperture) since use of a 1.4 extender causes a one f/stop loss, thusly making the lens a bit slower.

You can get some pretty impressive zooms if you use a digital camera instead of 35 mm. My Panasonic has a 12x zoom and image stabilization, yet it cost only about $250. At its maximum zoom the lens is equivalent to 420 mm on a 35 mm camera, and the maximum aperture is f/2.8 at any zoom setting. With the stabilization you can handhold it for 1/4 second and get sharp images.

I guess the maximum zoom for a 35 mm camera would involve using it with a variable length lens on an astronomical telescope.

hack saw a telescope down and you will find out?