Yes you can use it but you need a FD to EOS adapter.
The Canon AE1 lens will not fit a Canon digital. You can buy an adapter that will allow the lens to work in manual focus mode on the digital camera.
In short, yes. More specifically, as long your zoom lens is an "EF" mount lens, it will work with all Canon Digital-SLR models from the EOS line. You can determine if a lens is an EF mount from the full name of the lens. The full name of the lens is usually written on the outside of the len itself.
Yes. If the lens is a EF or EF-S lens, it should work fine with the t1i
It would depend on the type of lens mount. Generally speaking, it would probably not work too well. The AE uses full-aperture TTL metering, and its mechanism for manipulating the diaphragm of the lens is not likely to work with the "digital" lens, although that is not a sure thing. Try to gently mate the lens and body. If the lens will mount, shoot a roll of film and see how it goes.
If it's made for Canon, yes.
It's a walk around lens for canon digital SLR cameras. Also sold as the standard lens with Canon's digital Rebel line. EFS means that it was made by and for Canon. The S at the end means that it will only work properly on low & midrange digital models (not on film SLR cameras and not on Canon's professional grade digital bodies.) 18-55mm means that it goes from moderate wide angle to moderate tele zoom. The perfect zoom range for general use. f/3.5-5.6 means that it's not particularly suited for low light situations. You also can't achieve extremely shallow depth of field (blurry backgrounds) with it.
Any Canon camera with the EF-S lens system will work. That includes but isn't limited to all of the rebels (XT, XtI, XS, XSI, and the new T1I). The only cameras that WON'T work with your Rebel XTI lenses are Canon 1Ds, Canon 1Ds Mark II, Canon 1Ds Mark III, Canon 5d, Canon 5D Mark II. Another other Canon digital camera will do the job. The reason that these won't work is because they are full-frame cameras, which need a larger surface area of the lens and will not accept the mount from the smaller EF-S lenses. These cameras are all professional cameras and cost a couple thousand each.
A Canon L Lens is in the line of SLR photography lenses made by Canon. L lenses are Canon's top lenses and according to Canon's Lens Work III Book L is for luxury. They are used on cameras for better zoom and image quality.
Yes.
The... Canon EF 100mm f2.0 USM
It's a walk around lens for canon digital SLR cameras. Also sold as the standard lens with Canon's digital Rebel line. EFS means that it was made by and for Canon. The S at the end means that it will only work properly on low & midrange digital models (not on film SLR cameras and not on Canon's professional grade digital bodies.) 18-55mm means that it goes from moderate wide angle to moderate tele zoom. The perfect zoom range for general use. f/3.5-5.6 means that it's not particularly suited for low light situations. You also can't achieve extremely shallow depth of field (blurry backgrounds) with it.
It depends on the brand of camera and the type of lens. Most Nikon film SLR lenses will work (in manual mode) on their digital SLR cameras. Many Canon lenses will work on new Canon SLR cameras, but you have to check compatability between the camera model and the type of lens. Sony purhcased the Minolta digital camera division, so all Sony Alpha DSLRs will use Minolta lenses.