Originally posted by emr I'm afraid neither is wide enough on an APS-C camera. I actually already have a Tamron Adaptall 28mm f/2.5 which might be great - if it was 18mm...
Well, if 24mm isn't wide enough then you're looking for UWA (Ultra Wide Angle).
There is occasionally an M42 20mm. I've got a vivitar M42 20mm/3.8. Only drawback is that it has an 82mm filter thread mount on the front - ginormous!
So..... you'll find that "bargain" becomes a relative term when you're looking for an UWA lens.
edit: looks like Blue and I are on the same brain wavelenghth!