Why your exif data matters to me and to you.

and the ride goes aroundThis is a quick post about what the EXIF data actually is and how to use it for your own benefit and to help others.

EXIF stands for Exchangeable image file format.

When it comes to digital photos it means the metadata for that photo…  the shutter speed, ISO, Aperture and everything else about the shot.  Even depending on the lens that was used the lens specifications and model as well.  When you press play back on your camera and see the shot information, that has come from the EXIF info embedded in each shot.

Now this is where it gets really handy.  Because (and I will use Flickr as my example, but other sites use it as well) on Flickr you can see if enabled all the technical specifications of a shot.  It may be a clever shot of the moon that you can’t quite get right, or a long exposure you want to find out about.  With Flickr click on the Taken with a Nikon D90. More properties in the right hand column. This will lead you to a page that looks like this…. (cut back version)

Camera: Nikon D90
Exposure: 6 sec (6)
Aperture: f/14
Focal Length: 18 mm
Exposure Bias: 0/6 EV
Flash: Flash fired
Orientation: Horizontal (normal)
Date and Time: 2008:12:26 21:24:25
YCbCr Positioning: Co-Sited
Exposure Program: Manual
Date and Time (Original): 2008:12:26 21:24:25
Date and Time (Digitized): 2008:12:26 21:24:25
Compressed Bits per Pixel: 1 bits
Maximum Lens Aperture: 36/10
Metering Mode: Pattern
User Comment: (c)wolf(@)wolfcat.com.au
Sub-Second Time: 00
Color Space: sRGB
Sensing Method: One-chip colour area sensor
Exposure Mode: 1
Digital Zoom Ratio: 1/1
Focal Length In 35mm Film: 27
Compression: JPEG
Quality: BASIC
White Balance: AUTO
Focus Mode: AF-A
Flash Setting: REAR
Auto Flash Mode: Built-in,TTL
White Balance Bias Value: 0, 0
White Balance Red, Blue Coefficients: 438/256, 363/256, 256/256, 256/256
Thumbnail IFD Offset: 9210
Flash Used: 9
Bracketing & Shooting Mode: Shooting Mode: Single Frame AE/Flash Bracketing Off White Balance Bracketing Off
Tag::Nikon Type 3::0x008A: 2
Noise Reduction: OFF
Total Number of Shutter Releases for Camera: 12740
Image Width: 2144 pixels
Image Height: 1424 pixels

Of course all of this can seem rather intimidating to begin with (and more so once you do a bit of tweaking of the image in photoshop).

But with the above sample EXIF data you can see all you need to see about how the shot was done. For example
Exposure Program: Manual, tells me the camera was in manual mode… but
Focus Mode: AF-A, tells me the camera was in auto focus mode.

(This is for the above shot of the Side show ride at Semaphore Beach taken Dec 26 08)

Fire MoonSo just from these two bits of information I can see how the photographer (in this case me :-)) has done key aspects of the shot.

Now like the earlier post on using Auto Mode to dial in Manual Settings… you can use this information to dial in a set up for a manual shot based on someone else working out the basic configuration.

This is not going to teach you how to do composition and the more ethereal aspects of photography, but it can give you a leg up on getting the camera set up.  The rest is up to you.

Now… you will see all my shots have EXIF showing… some people get fussy about that.. me I am not one of those…  for the following reason..  a good photographer will be able to look at any shot that you have put on flickr and work it out.. just by looking at the shot, so what is the point.  The other reason is that you can use your own flickr images and EXIF data to see how you did a shot.  The shots of the moon I have… I can never remember the settings… so I just search my own flickr stream look up the EXIF data and there is how I did the shot 🙂

In Flickr.. in account settings “Hide your EXIF data” is what you are looking for.

(See this blog post for dealing with geodata privacy)

Final Pro Tip: Adding your name to every shot on the Nikon D90

You will also see that every shot of mine also says

User Comment: (c)wolf(@)wolfcat.com.au  (the brackets around the (@) do help to stop spammers getting your email address!)

which means every shot of mine has a copyright info embedded into it.  Sure some one can delete it if they want to… but.. if for example your camera was stolen.. you can show the cops that the shots are yours very quickly.  (I have seen this happen!)

To set this …  on your D90

Press  MENU > Set Up Menu > Image Comment > Input Comment > (then like old school style scroll letters to get what you want.  For some annoying reason Nikon’s don’t have the © symbol so (c) is a close as you can get.) > Enter.

You must hit ENTER or it will forget everything you just did, (took me 3 goes to get it right!)

P.S… the Moon Image… guess what I couldn’t get it right… 2 min later on Flickr and I had the settings I was looking for 🙂

2 Responses to “Why your exif data matters to me and to you.”

  1. Good post wolf,

    I think you’ve even missed some other possible future benefits of having accurate EXIF data…. beyond just improving your own photography.

    Imagine when something like Microsoft’s Photosynth technology scans over all the images taken in an area, the extra information that can be gleaned by having EXIF information:

    – compare the shape of objects in an image to its focal length.. to more accurately map the space in 3D
    – compare the shutter speed and ISO against the time of day and image brightness to get an idea of the weather at the time

    Put simply, the more EXIF (meta)data there is the more awesomely useful things technology can do with your pics.

    More info on photosynth here:

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