Exif aperture larger than possible for the used lens

Question

A photo shot with an 1:1.8 lens contains the following exif data:

ApertureValue: 1695994/1000000  
MaxApertureValue: 16/10

How is this possible? Both values are <1.8

Answer

I have seen that exact value (16/10) on a Nikon before. It may just be an incorrect value as Matt says. It could also be a calculated value adjusted for:

• focus distance info from the lens, which affects the apparent aperture
• adjustment for low ISO (i.e L.03 or L.07)
• adjustment for exposure compensation
• FX lens on a DX body

For example if you had ISO set on Nikon to L.03 the EXIF data might report ISO 200 and the aperture open a stop wider than it can actually go.

If you can share more information about which camera and lens, and other EXIF data we might be able to make a better guess, but the main point is you can't completely trust EXIF data.

You can also get different results using different EXIF readers. What reader are you using, and what value is reported by your processing software (Lightroom or Aperture or whatever)?

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