Does the Old nikon Film slr lens compatible with nikon Dslr?

I have old lenses for FG-20 film SLR and thinking if they can be used to new models of Digital SLR.

It depends

I have some old manual focus lenses converted to AI that work perfectly well on both my 35 mm F4 and my full frame dSLR D3. I have to manually focus them but they work just fine

Any AF, AF-I and AF-S lens will work on any of the Nikon D90 or higher cameras.

The entry level cameras ($1, 000 or less), require the user to buy the newest AF-S, fast auto-focus lenses. After all, someone new to using dSLR's is NOT expected to own a lot of legacy lenses.

The FG-20 was a compact Nikon 35mm slr that used AI or AI-modified lenses, including the economical E-series.

Those lenses will mount on any current Nikon DSLR, but will not autometer on them, since they don't have the required electronic contacts. If you are using a D7000, D200, D300, or up, you can use these lenses perfectly, after setting the maximum aperture in the camera's menu.

On an entry level camera like the D3100, D51000, or such, you can mount and manually use the lenses.

Maybe this would be of great help to you. It's the lens you should be concerned of. Try to figure out what exactly their model is.

http://www.kenrockwell.com/...y-lens.htm

The FG-20 is a 1984 camera, much earlier than the oldest listed in that page but it already used the Nikon F-mount. My guess is the lenses that came with it were AI or a variant of it. Those should mount any modern digital Nikon SLR but the lightmeter will not be active with the D90 and D3100. For full functionality, look at the D300 and the D3. Those are just representative models. Check the link about the other models in their groups to know which are the same as those I mentioned.