In article <310bfc35.12621160@news.tiac.net>, jmusto@tiac.net says...
>>TGP wrote:
>>Can I change lenses on my SLR midroll without having
>>> to worry about exposing the film?
>>"Edward J. O'Rourke, M.D." wrote:
>>Never a great idea in bright sunlight . . .

>Please explain this. No more light gets in the body with the lens off
>than on. In fact with the lens on, it is focused on the film plane.
>Why would it matter if you change lenses in direct sunlight?

The "aperture" of the lens lets in less light, and most of the light that is let in by the lens is reflected by the mirror to the viewing screen (which is one advantage of SLR's over rangefinder focal-plane
shuttered cameras [which can also get holes burned in the shutter if
the sun is focused on the shutter in one place for very long]).
Hope This Helps