[wilsonng]

I would create a project in OmniFocus for that photography session. This includes all the necessary steps to complete that project.

After entering all the tasks that make up the project, I'll highlight the project itself and select Edit > Copy As Link.

Then I would go to iCal and create a new event. Let's say Monday, 1:00 pm to 5:00 pm.

In the URL entry, I would paste the link from the clipboard.

So when the time comes, I can open iCal and click on that link to go to the project in OmniFocus. I'll be concerned with just the tasks in that project alone and won't bother looking at other tasks/projects.

This may took some adjustment on your part to think of it this way. YMMV