EXIF and Other Mysteries… MR Photography Workshop Park Place Porsche in Dallas August 23, 2014

The Exchangeable image file format [officially Exif, not EXIF…but you will rarely see it that way] is a standard published and maintained by JEIDA [now JEITA] and CIPC for the metadata recorded by cameras. It is not supported in JPEG 2000, PCX, or GIF. With that stuff behind us, let’s look at what kind of metadata is stored in the EXIF area of digital pictures. EXIF fields have an “address” that vary from “0x0000” to “0xFFFF” but not all addresses have been assigned [yet]. Thus, there are a total of 10,000 hexadecimal fields possible. For those of you that don’t have a Hex2Dec converter handy, that’s 65,536 decimal. Unfortunately, as w/ most standards that have hundreds of contributors, the EXIF is a total mess! But that should not bother you, as most of the obscure tags are not used and not interesting to “normal” photographers. The parts you will be interested in can be easily viewed and even modified. There are many software programs that give you access to the EXIF data in your images: Exiftool(-k) and ExifToolGUI [they work together] Opanda IExif FileTagSleuth Those are just a few of the many available for the PC [I’m sure there are some for the Mac too].

But the easiest program to use may be Lightroom. Its Library Module has a comprehensive “Metadata” section in the right pane: The snip to the right is only a part of the data; I could not get it all on the page. Even if I did, LR only shows a portion of the total metadata, but it’s enough. Just be aware that there are a lot of extraneous fields not normally shown in any program [because they are not relevant to your photograph]. I have displayed not only the EXIF data, but also the “IPTC” data. “IPTC” stands for International Press Telecommunications Council who developed an Information Interchange Model for information such as the name of the photographer, copyright information, the caption or other description, model name and contact information, etc. Gradually all these different metadata standards are merging it seems. We tend to call them all “EXIF” for generic simplicity. At the bottom of the snip, notice that Brian has stored his name in the “Creator” field. You should all follow his example!

So, how does knowing about the EXIF data help you? Well, it allows you to go back and determine how you used your camera to take a picture. Why, you ask, would I want to do that? Perhaps the image didn’t quite turn out as you expected. Having all the EXIF data at your disposal can allow you to make a good guess what setting might have been “wrong”? For example, the EXIF data on the previous page was contained in a picture that Brian O’Hearn took of our cars: Did you notice that it was taken at f/2.8 and 1/2500 second? I would have thought a smaller aperture would be better in daylight? What do you think?

My first concern was that the Depth of Field might be too shallow at f/2.8, so I used Barnack: I SWAGged that the distance was 100 feet; all the other variables are what was recorded in the EXIF for that picture. You can see that the DoF is 626 ft so my concern was unnecessary. But would the picture have been sharper at f/8? Probably, but Brian was using a 55mm Macro lens, that is quite sharp. But the Blur Circle IS smaller at f/8:

Note that there is a GPS area defined, but since Brian’s D700 doesn’t have GPS capability, nothing is stored in that section. If you have a camera w/ GPS, be cautious that you don’t inadvertently post a picture on line that tells someone where a priceless old Porsche is stored. Many apps have a feature to eliminate all the EXIF data or just the GPS data component when uploading to social media sites. If you have a camera that receives GPS signals, the metadata will look something like this: If you click on the right-arrow box, the Map Module is selected w/ little colored boxes that allow access to all the photos at that specific location [and a film strip with GPS-tagged images selected]:

SO, what can this EXIF metadata do for you, other than entertainment? 1.It informs photo editing software what camera settings you used. This is important so that the software can use those settings when rendering a JPEG from the RAW data. In this way, the software will mimic what the camera would have done, had it rendered a JPEG. 2.You, the photographer, can look at the EXIF data to see why an image didn’t turn out as you intended [for example, you forgot to turn off some feature not appropriate for the subject image]. 3.You can send an image that didn’t turn out quite as you hoped, to an internet guru who can look at the EXIF data and the image and explain what happened. 4.You can use the EXIF data to help you remember when/where/how you took a picture. 5.You can use the EXIF data to prove an image is yours. 6.You can use the EXIF data to prove an image is NOT yours! 7.You can send the EXIF settings to a friend who is having difficulty w/ a specific picture and suggest s/he try those settings. It rarely works as intended, but what are friends for? 8.You can use EXIF data to prove you were not at the scene of the crime.