Windows or MacOS? FMP version?
FM Pro 11 Adv
I have MacOS so I can't speak to how the Window's File Location Dialog defaults. You might want to move the Picture Folder or use a scripted File Path to force it.
I've tried a number of options on My windows machines and haven't found anything that works such that the next open file dialog defaults to a specific location. Frankly, I think that would be a very useful new feature: http://www.filemaker.com/company/contact/feature_request.html
It is possible to put up a list of files from a specified directory in a text field and clicking a listed file can insert it into a script designated container field. To get the list of files, requires either using a system script to list the directory contents, a plug in, or you put your picture directory inside the documents folder and parse the list using the Get ( DocumentsPathListing ) function.