I am trying to convert a PDF poster I have downloaded to a JPEG as this is the only format the printers will accept but my Abobe does not give me this option. Am I doing something wrong?
If your "Adobe" is the free Acrobat Reader, it doesn't do that. You could pay for a service, but why not instead find a printer that can do the job. Or, ask the copyright holder if they have a JPEG for you to print, sometimes it's worth asking.
Excellent advice from @Test Screen Name.
I'm concerned by the printer's request for a JPEG file.
Years ago, the PDF file format was originally developed to specifically send files to print shops and prepress. So any printer who can't accept a PDF file is ... well, nuts.
Find another print shop.
And if you do end up converting the PDF to JPEG, you'll lose a lot of quality in the file (color, resolution, clarity), even if you could make a high-quality JPEG.
Thank you for your response Bevi and I have taken your advice and found another print shop. I did think it a little strange that a jpeg was requested - seemed to be going back to the dark ages!!