Dave!
I don't think you need a barlow for imaging with the ED80. It's a f/7.5. With a typical barlow it will be f/15 which is awful slow for all but the brightest targets. If you're thinking you want more magnification for planets, there is little point as the scope does not have the resolution for detailed planetary images anyway. On the Moon it might make sense to use a barlow. I have zero imaging experience btw.