Bought my first dSLR since owning Canon AE-1, and Canon SX500IS. Have Canon T2I with kit 18-135 lens. I bought Zykkor FD adapter so I could try my old Canon AE-1 lens. Now have the Canon FD 50 mm/1.8 lens attached and want to learn from it Would like to learn basic photo with this combo and would like any suggestions from the "experts" Thanks
You should learn by using the kit lens... don't try to use the FD lens (yet.)
Buy a copy of "Understanding Exposure" (by Bryan Peterson) or alternatively you can buy the Scott Kelby Digital Photography series of books (I think he's up to four volumes now.)
The single-volume "Understanding Exposure" is probably the more popular and is geared toward teach beginners the basics of using a DSLR camera by learning to shoot in manual so that you grasp what happens when you change shutter speed vs aperture vs. ISO and why even though two completely different settings result in the camera capturing the same amount of light, the images you capture can look very different.
The problem with the FD lens is that it'll be more challenge than you should be trying to take on right now because it doesn't work the way any of of the EOS lenses.
The FD lens doesn't have any electronic communication with the body. It also has no focus motor. You'd have to manually focus the lens. On your AE-1 you'll notice you have a nice HUGE BRIGHT viewfinder with a giant split-prism (two half-moon shapes) in the center which show when your focus is correct by causing a subject in those two half-moon shapes to appear in phase or out of phase with respect to the other half of the moon. It's then surrounded by an array of micro-prisms which further help as a focusing aid.
Your T2i, on the other hand, has no split-prism focusing aid in the viewfinder... in fact it has no visual aids at all. It shows you where the AF points are that the camera would use (if only you had an auto-focusing lens). Since the T2i is a crop-frame sensor body, the mirror and viewfinder are much smaller than they are in your AE-1. You'll notice the edge-to-edge view that your eye sees isn't nearly as large nor as bright as your AE-1.
Lastly, the AE-1 can automatically control the f-stop on the lens but your T2i cannot. The aperture is mechanically controlled by the AE-1. You can press the small black button to the right of the green letter "A" on your aperture ring (on the lens) to unlock it and this will allow you to manually dial in the f-stop you'd like to use, but the "through the camera" metering can't control the aperture.
When you've thoroughly understand how aperture, shutter, and ISO work together to control exposure and are able to do it with your T2i and kit lens backwards and forwards, in manual mode (or any other mode) THEN you can grab your 50mm FD lens and have some fun with it. But if you try to control the lens before you even understand what you're controlling or why you're more likely to just get confused and possibly frustrated.