scanning multiple pages with scanimage

I wish to scan multiple pages with my HP ENVY scanner, it does not have a page feeder. I don't mind where the files are created or what name and type they are, I'll convert them to a single pdf file after scanning. Have tried:-

scanimage --batch  --batch-prompt  --resolution 150

And various other permutations but get scanimage: sane_start: Invalid argument all the time.

Any advice would be welcome