Converting a Pentax 28-85mm problems

Hey guys I need some help!

I recently got a Pentax mount Vivitar 28-85mm lens off ebay. Today I got my Fotodiox Pentax K to Nikon mount adapter and everything fit just fine, but now my camera won't recognize that there is a lens attached. I can take pictures, zoom, focus, and control the shutter speed, but I cannot change the f-stop. Anyone know what is going on or how I can fix it?

Thanks.

Would need to know about the lens, but if there's a manual aperture ring on the lens make sure it's set to the smallest (highest number) aperture.

You also won't see any changes to the aperture until you actually take a pic. Camera keeps the lens wide open for you to focus easier until you actually make a shot.

If it is the same lens that i found through google, you will have to use the lens in M or Manual Mode. It would really help in telling us what lens you have (a picture maybe?) I have an old Vivitar 400mm and you have to change aperture manually on the lens. If the lens has no CPU on it, i doubt that you can control the aperture from the camera. Good chance you will not be able to meter either. Again, let us see a pic of your new lens. Thanks

You first have to put your camera's settings on Manual, select a shutter speed and aperture on the ring of the lens and iso and trial and error will eventually produce a picture.

You are on a looser with this one ...there are Four types of adaptor ring ..one has no lens in it and you will not be able to focus at infinity. the other has a lens in it which allows infinity focus but the quality is substantially reduced. the third will have a rotating ring that will couple to the lens aperture control and allow you to open and close it manually. If the lens has electrical contacts then for some lenses an adaptor is available to couple the electronics,,,,, If you buy these things on e bay then its important to read the small print on what functions it will support.

Why would you want to use a Pentax lens on a Nikon? There are so many Nikon lenses on the used markets that I have to question your choice...

if you got one or its real cheap you often get sucked into this with a $10 adaptor....If you are into 4/3 particularly for video then fitting strange lenses is very popular....