How do i slide a nikon d90 lense on - Nikon D90 Digital Camera with 18-105mm lens

Did you switch the Focus-mode selector to MF?
It is the switch with number 8. Perhaps you are used to switching on the lens, but on the body is also a switch. Normaly used for the older AF lenses.

Tamron makes their lenses with a variety of lens mounts. If your lens has a Nikon mount then it will mount onto the D90.

Vivitar makes lenses for a variety of cameras, so a lens for a Canon, for example, will not fit onto a Nikon. Assuming the Vivitar lens has a Nikon mount, then yes, it will mount on the D90 and yes, it will autofocus properly on the D90.

The lense will probably work with an adapter. try ebay. i purchased one for my canon lenses for macro work. note that the focal length of the nikon is 46.5 and the minolta is 43.5 and infinity will not work with out an adapter with a correcting lense. you will find a adapter with out a lense will work fine for macro.

Yes and no. Physically they will all fit (with very rare exceptions, such as the 6mm f/2.8 fisheye).

Most Nikon dSLRs have a sensor that is smaller than a frame of 35mm film. What this means is that you end up using only the central area of each lens. In effect this means that each of your lenses is effectively 1.5 times longer. A 200mm lens on a digital camera will give you the same angle of view a 300mm lens on a film camera gives you. The D3 family and the D700 are the exceptions, behaving similar to a film camera in this respect.

Older Nikon lenses do not have the electronic circuitry necessary to communicate with newer cameras. In the case of the D90, this means that such lenses will not communicate with the camera's exposure meter. They can still be used in Manual mode, but without assistance from the meter. You'll need to move up to a D300 if you want to meter with such lenses.

Bear in mind that lens technology continues to improve every year. Given an old lens and a new lens of similar focal length (or zoom range), the new lens will almost invariably outperform the old one.

Hello,
The Nikon D90 works well with the Nikon AF 50mm lenses and most other brand Nikon fit AF lenses. If they are not AF you will lose autofocus and metering.
Do you know that on the D90 the lens becomes a 75mm but the aperture stays the same, so for instance the 50mm f/1.8 is a 75mm f/1.8.

This is the OS setting up its normal

This is a lens for Sony/Minolta cameras. It is not compatible with the Nikon D90. Hence a Teleconverter for Nikon will not work on this lens to mount it to a Nikon D90.

This lens is too old for the D90, it has not got the electronics for metering and autofocus.
You can use it manually in M mode but you will have to set the aperture and shutter yourself.
The D90 manual has a section on compatible lenses, page 228 in my version.
This recommends CPU lenses for the D90, type G and D.

All old lenses will work on the D90 the same way they work on the D80. Filters depend on the lens -- they either fit or they don't -- the camera has nothing to do with that. I wouldn't use old flashes on new DSLRs.

There really is no difference between the D80 and the D90 as far as lenses and flashes are concerned.