Troops:
Never used one and running out of ideas on Cookie's gear with her birthday approaching. Mostly wildife interests for her.
Is there any perceivable image degradation with their use? I know one gives up about an F-stop. I've done a little surfing, and it looks like most of her Canon lenses would still be fully functional. I've not bumped into any tests, however, addressing resolution issues. Thoughts on about a 1.4X would be appreciated.
