Thanks again, Scott.

Dust is mostly an over rated problem, I rarely even think about it.  I
am swaping lenses all the time and have very little trouble.

Pretty much the only problems you will run into is higher f numbers,
like f/16 and
even then it is normally not a big problem.

And cleaning the sensor is not all that hard either.

Scott

OK. Next question, if that's OK...

I've read (here) about dust contamination on a digital camera's CMOS
sensors. Is it a big issue to swap these lenses back and forth in a
relatively quiet space? Or, are we talking *surgically clean.

My pictures are mostly for home use, but I've published magazine photos and
that was the purpose of my new purchase.

The EF-S lens is designed for the Rebel digital cameras and won't work
on the film models.  The Rebel digital sensor is smaller than a film
frame, and that allows the EF-S lens to be smaller and less expensive.
But that also makes it inherently incapable of covering a film frame
or a larger sensor (like the EOS-1DS series).  So there is no adapter.

I bought a new Canon EOS Digital Rebel XT and it works great. It came with
an 18 - 55 mm lens.

I already had a Canon EOS Rebel film camera with a 35 - 105 mm lens.

I swapped the bigger film lens to the digital camera and it seems to work
fine, but the new lens won't attach to the old film-camera body.

What am I missing? Do I need an adaptor?