I am trying to edit a PDF in Photoshop. I want to keep the white margins on the page, but each time I pull the PDF into Photoshop, it automatically crops to the size of the image on the page. I previously used Adobe CS5, and I was able to adjust the canvas size after flattening the image to adjust my white space accordingly (Sometimes I need white space around my image, sometimes not). Now have Creative Cloud and cannot figure out if this is a setting I can change.
You need to change which boundary you are cropping the PDF to, when you open it.
Use the options in the menu that is presented to you, when you initially open the PDF.
According to Adobe's website:
Crops to the original size of the page.
Crops to the clipping region (crop margins) of the PDF file.
Crops to the region specified in the PDF file for accommodating limitations inherent in production processes such as cutting, folding, and trimming.
Crops to the region specified for the intended finished size of the page.
Crops to the region specified in the PDF file for placing the PDF data into another application.
I usually use Trim, for what I think you're after.