I have an old Canon EOS 1000 with 2 lenses:

a 35-80mm and an 80-200mm

and I'm thinking of getting the Brevis 35mm adaptor, are these lenses worth keeping/using or should I get other lenses.

Any recommendations?

Are they constant aperture throughout the zoom?
What aperture?

absolutely no idea :-) - how do I tell?

the only markings on the lens are

canon zoom lens EF 35-80mm 1:4 - 5.8
canon zoom lens EF 80-200mm 1:4.5 - 5.6

found the answer -

http://dvinfo.net/conf/showthread.php?t=96416

Normally those lenses would be a bit slow for adapter use, however they'll shine with the Brevis35 and our CF1L (or CF1 if it's a small cam) imaging element.