Q) I know that I’m going to have to enter the digital age, but right now I can’t afford to jump into it with both feet. I’d like to buy the best camera body (most likely EOS) I can afford, but would like to be able to use the fleet of FD mount lenses that I used with my older Canon F1 and FTb until I can afford better lenses and while I brush off the cobwebs and relearn the photographic thought process and techniques. On the Internet, I’ve found references to adapters that can be purchased that will enable this, but there was little actual technical information. I’d like to know if you’re familiar with such an adapter and would be interested in your thoughts on the matter.
A) You can use other manufacturers' lenses or previous types of mounts on a newer style camera body with special adapters. Before I get into this, I want to say that unless you have a really good reason, I wouldn't do it. With an adapter, you'll lose many, if not all, of the features available in today's cameras. Autofocus won't work; the automatic diaphragm, where the lens stays open for focus until the last moment, won't work; and if you have an adapter that doesn't have an optic in it to make up for the change in focus distance of the adapted lens, it won't focus to infinity.
There are two types of adapters. A simple version without any optics sells for about $50 and will allow the lens to mount. No other features of the lens or the camera body will work. If you're using the adapted lens for macro work, it may not be a major issue.
The second type of adapter has an optic center that corrects the focus distance to match the camera and adapted lens. These range in the $200 area, and you're at the mercy of the quality of the adapter's optic. Usually it won't match the quality of the adapted lens and will be the limiting factor in the resulting quality. Be aware that you still won't have autofocus or automatic diaphragm with this type of adapter.
Trying to cope with these kinds of impediments only will frustrate your learning to photograph and process images in the digital realm and will greatly decrease your enjoyment of all that digital has to offer.
Shown here are the two types of adapters mentioned in the question and answer above. On the left is the basic adapter without any optics that won't focus to infinity. The right adapter has optics and corrects for the different focusing points of a lens not designed for the newer Canon EOS camera bodies.