What's Wrong With EXIF?

2010.01.29

EXIF is the format used to store information in a digital image. Photographer really appreciate having that information as it tells them what settings they used to take a picture, information such as the camera model, focal-length, f-stop, shutter-speed, ISO and much more. Most modern image viewers such as PMView Pro of Geeqie have an easy way to show EXIF data. EXIF is a relatively old standard, technologically speaking, with version 2.2 published in 2002.

Given the standard's age, one would think that every recent imaging software would know how to handle it properly. Yet most catalogging software get something wrong. On the right is example from IDImager. Notice how there are 2 Nikons, 4 Pentax and 3 Sony makes? Intuitively you would think that perhaps a camera produces EXIF info spelled slightly differently (as in Pentax vs Pentax Corporation) or some have spaces after the name and therefore it would appear under one maker or another. However, Bibble Pro confuses things further by trying to group camera models under their makers and things get even more silly because of that. For example, it shows the same camera model under two different brands, like the Pentax K20D which appears under PENTAX and under PENTAX Corporation. What the heck?

Another piece of information found among EXIF data is an identifier for the lens used. This identifier does not seem to be the actual lens info but some kind of number which has to be translated into a particular lens model. It appears that Bibble Pro guesses instead of using that information as it produces a catalog with a huge list of lenses, some of them I did not even know existed. It seems to also do that every time, so even if it would guess correctly that a photo was taken with the Canon 70-200mm F4 for example, another photo taken from the same lens may appear as taken with the Canon 200mm F1.8. Very strange.

At first glance, Lightroom seems reasonable with no confusion of makes and models, although it does not try to group them. The list of lens contains one entry called Unknown Lens which references about half my photo collection. However one lens was clearly substituted for another to the point of absurdity where Lightroom reports I used a Pentax F28-80mm F3.5-4.5 at 24mm! Ooops.

IDImager gets shows a long list of lenses. Some lenses are the actual ones I used, such as a EF 50mm F1.4 USM, some are the wrong lens such as the Sigma 18-125mm F3.5-5.6 (with several pictures taken with it at F/2.8), and some are listed as a set of 4 numbers, like an IP address (0,0,226,8). Initially I thought that, instead of grouping unrecognized lenses into an Unknown Lens category like Lightroom, it simply marked them using the lens identifier. After a closer look I saw that pictures taken with some lenses, for example the DA* 50-135mm F2.8 sometimes appeared associated with the right lens and sometimes appeared associated with lens 0,0,241,8.

If someone can explain this, I'd really like to know what is going on here.

• Digital Photography