Flickr EXIF Search, Part 2

I’ve done a bit of experimentation and learned a few more keywords one can use to search for photos in flickr by their EXIF data. I have also gleaned the pattern that seems to have been used for coming up with the keywords. They appear to be abbreviations.

Keyword	Meaning	Abbreviation for	Unit
xel	minimum exposure	EXIF exposure lower limit	seconds
xeh	maximum exposure	EXIF exposure higher limit	seconds
xfl	minimum focal length	EXIF focal length lower limit	milimeters
xfh	maximum focal length	EXIF focal length higher limit	milimeters
xal	minimum aperture	EXIF aperture lower limit	f-number
xah	maximum aperture	EXIF aperture higher limit	f-number

Perhaps there’s a way to specify an exact exposure, focal length, or aperture without having to use both the lower and higher limit keywords together. If so, I haven’t found it yet.

I also haven’t yet figured out how to specify fractional exposure times (shutter speeds of less than one second). It seems to treat all decimal values less than 1 as simply 0. The text displayed above search results is not always correct. For example, when one uses xel or xeh to search for photos taken with fractional exposure times (shutter speeds of less than 1 second), the text displayed above the search results incorrectly rounds the fractional exposure times down to 0. Similarly, when one performs a search using xfl or xfh independently, the wording displayed above the search results does not correctly reflect the way these keywords function. The words shorter and longer are interposed.

Obviously, not all of the kinks have been worked out. Maybe that’s why these keywords remain undocumented. I have started a discussion thread about this in the flickr ideas group.

Flickr EXIF Search

Flickr EXIF Search, originally uploaded by blech.

Recently, I have begun to tag each of my photos with information about the camera and lens used to take the photo. It’s easy to add another tag to a batch when I’m uploading new photos. However, it’s a bit more time-consuming to go through my old photos on flickr and determine which photos were take with which lens.

Then I had a thought: the camera model used to take a photo is encoded in the photo’s EXIF data; so are the focal length, shutter speed, and aperture. The specific lens used is not included in the EXIF data, as far as I know. But using the information that is is there, it ought to be possible, I thought, to locate all the photos that were taken with a particular lens.

This led me to search for a way to locate photos on flickr based on their EXIF data. Amazingly, there's very little information out there about how to do this. I did find this one photo though, and in it one can clearly see two search parameters that don’t seem to be publicly documented by flickr:

• xfl — the maximum focal length; find photos with this focal length and shorter;

• xah — the minimum aperture (maximum f-number); find photos with this aperture and wider (this f-number and smaller).

Using these parameters, it's possible, for example, to perform the following search:
Find all of my photos tagged with climbing, with an aperture of f/2.7 or wider, and with a focal length of 50mm or shorter.

I have only one lens faster than f/2.8: my 50mm f/1.4 prime lens. So any photos returned by this search must have been taken using this lens.

Does anyone know if these and other EXIF-related search parameters are documented anywhere? I'd really like to learn more about how to perform searches using EXIF data.

Also, I would really like to know how to perform batch operations on the search results. Is there a way to add all of the results of a search to a batch in the flickr organizer? If not, there ought to be.