The benefit of search engines is: They let you find what you are looking for. This is a remarkable feature by itself, given the wealth of information available.
Sometimes, one even finds what one is not looking for, and since this comes as a surprise at that moment, it is even more remarkable.
This happened to me the other day. I was looking for information on how people use Lightroom’s Smart Gallery feature to structure their media or to organize their workflow, so I was quickly scanning Julieanne Kost’s blog entry about creating a query looking for photos without keywords, when in a comment on that entry I found something I wanted to have for a long time and always thought Lightroom was not capable of.
Turns out this powerful feature was just hidden very well. Kudos to Mr. Mike Nelson Pedde for pointing that out. He is sharing a lot more information about Lightroom on his site wolfnowl.
The important bits are these: When you create a new Smart Gallery, you get a flat list of conditions that have to be met, and you can specify whether you want to apply a logical AND to them (all of them have to be met) or a logical OR (at least one of them has to be met).
So how would you create a query for “Show me all the images that have at least five stars and where keywords contain “Foo” or “Bar”? With this flat list of conditions, you can’t. You need an AND and an OR for this, and you can only have one of them.
But obviously, if you hold down the ALT key while pressing that little plus sign on the right (which turns into a hash symbol when doing that), it does not create another sibling condition, but instead a child condition.
This query now reads like Rating >= 3 AND (Keywords contain “Foo” OR Keywords contain “Bar”). The braces are here to indicate logical grouping being applied by this child condition. You can nest these child conditions even deeper, so this makes a HUGE difference in the way you can create smart galleries and gives you a lot more power.
Hope that helps